Oracle Video server User Manual

Oracle Video Server

Introducing Oracle Video Server

Release 3.0

February 1998
Part No. A53956-02



Introducing Oracle Video Server
Part No. A53956-02
Release 3.0
Copyright © 1998, Oracle Corporation. All rights reserved.
Printed in the U.S.A
Primary Authors: Brian Linden, Matt Prather
Contributors: Kim Bartlett, Chris Bedford, Frances Buran, John Dowden, Gordon Furbush, Jean

Giarrusso, Dana Hausman Izenson, Lesley Kew, Liz Landreth, Ming Lee, Sue Lee, Alex Lind, Martin
McKendrick, Mason Ng, Jeffrey Olkin, Dave Pawson, Mark Porter, Pat Ritto, Daryl Rosen, Andrew
Samuels, Shawn Shyh, James Steel, Sean Trabosh, Daniel Weaver, John Zussman

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Contents

Send Us Your Comments

Preface

............................................................................................................................................................

...................................................................................................................

Chapter 1 Concepts

What Is Streamed Digital Video?

How Is Streamed Video Better than Traditional Media?........................................................

What Is a Digital Video Server?

What is the Oracle Video Server?...............................................................................................

OVS within the Network Computing Architecture (NCA) ............................................

Tier 1: Client...........................................................................................................................

Oracle Video Client:.......................................................................................................

Oracle Video Server Manager: .....................................................................................

Tier 2: Application Server ....................................................................................................

Tier 3: Data Server.................................................................................................................

Server Layer ...........................................................................................................................

Cartridge Layer......................................................................................................................

Communication Layer..........................................................................................................

What is a Digital Video Client?

Customizing the Video Client ....................................................................................................

What Are the Challenges of Digital Video?
How Is Digital Video Used?

Clips and Logical Content...........................................................................................................

Real-Time Feeds..........................................................................................................................

Where is Digital Video Used?

.............................................................................................................

........................................................................................................

....................................................................................................

.......................................................................................................

........................................................................................................

..................................................................................

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1-1
1-2
1-4
1-5
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1-6
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1-7
1-7
1-7
1-7
1-7
1-8
1-8
1-9

1-9
1-11
1-11

iii

Broadband

...................................................................................................................................

Asynchronous Transfer Mode (ATM)..............................................................................

Digital Subscriber Line (DSL) Transport Systems..........................................................

Enterprise
Internet

....................................................................................................................................

.........................................................................................................................................

Putting It Together: The Video Round Trip

All Environments........................................................................................................................

1. Client Tier..................................................................................................................

2. Network.....................................................................................................................

3. Application Server Tier ...........................................................................................

4. Data Server Tier (Optional).....................................................................................

Scenario 1: Broadband Environment .......................................................................................

Scenario 2: Enterprise Environment.........................................................................................

Scenario 3: Internet Environment.............................................................................................

Beyond the Basics

.............................................................................................................................

Maintaining an OVS System .....................................................................................................

Creating Applications ................................................................................................................

Chapter 2 System Architecture

.................................................................................

1-11
1-12
1-12
1-13
1-14
1-15
1-15
1-15
1-15
1-15
1-15
1-16
1-18
1-19
1-20
1-20
1-21

Oracle Video Server (OVS)

...............................................................................................................

Content...........................................................................................................................................

Physical Content....................................................................................................................

Compression Formats....................................................................................................

MPEG (Motion Pictures Experts Group) ....................................................................

Container (Mux) Formats..............................................................................................

MPEG-1 System and MPEG-2 Transport....................................................................

RKF (Raw Key Frame) Container Formats.................................................................

Tag Files...........................................................................................................................

One-Step Encoding.........................................................................................................

Continuous Real-Time Feeds........................................................................................

Logical Content......................................................................................................................

Storage............................................................................................................................................

Real-Time Access...................................................................................................................

Files..........................................................................................................................................

Write Consistency ..........................................................................................................

iv

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2-2
2-3
2-3
2-3
2-4
2-4
2-4
2-5
2-5
2-6
2-6
2-6
2-7

Volumes..................................................................................................................................

Striping ............................................................................................................................

RAID (Redundant Arrays of Inexpensive Disks) Protection...................................

Space Allocation...........................................................................................................

Spare Disks....................................................................................................................

MDS Utilities........................................................................................................................

HSM (Hierarchical Storage Management).......................................................................

HSM Utilities.................................................................................................................

Remote Access .....................................................................................................................

Delivery........................................................................................................................................

Requesting Video ................................................................................................................

Rate Control .........................................................................................................................

Real-Time Feeds...................................................................................................................

Scheduled Video..................................................................................................................

Looping Content..................................................................................................................

Network .......................................................................................................................................

Oracle Video Server Manager (VSM)

...........................................................................................

Graphical User Interface............................................................................................................

Oracle Media Net

..............................................................................................................................

Clients and Servers.....................................................................................................................

Objects, Interfaces, and Servers................................................................................................

Scalability and Load Balancing.................................................................................................

Logging Error and Warning Messages....................................................................................

Oracle Video Client (OVC)

.............................................................................................................

Application Development.........................................................................................................

Run-Time Capability..................................................................................................................

OVS System Hardware and Network Architecture
How the OVS System Communicates

..........................................................................................

...................................................................

Circuits.........................................................................................................................................

Sessions ........................................................................................................................................

Sessions in Symmetric Networks......................................................................................

Sessions in Asymmetric Networks ...................................................................................

How Client Devices Connect to the OVS................................................................................

How the OVS Delivers Video...................................................................................................

Components of Oracle Video Server and Oracle Media Net

...................................................

2-7
2-7

2-8
2-10
2-11
2-12
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v

Oracle Media Net ORB Daemon...............................................................................................

Oracle Media Net Name Server................................................................................................

2-26
2-26

Oracle Media Net Address Server............................................................................................ 2-26

Oracle Media Net Event Logging Daemon............................................................................. 2-27

Oracle Media Net Event Log Reader ....................................................................................... 2-27

Oracle Media Net CORBA Event Service................................................................................ 2-27

Oracle Media Net CORBA Naming Service ........................................................................... 2-28

Session and Circuit Service........................................................................................................ 2-28

Oracle MDS Directory Service.................................................................................................. 2-28

Oracle MDS Remote File Service.............................................................................................. 2-29

Oracle MDS FTP Service............................................................................................................ 2-29

HSM Service ................................................................................................................................ 2-29

HSM Transfer Service................................................................................................................. 2-29

Stream Service............................................................................................................................. 2-29

Video Pump................................................................................................................................. 2-30

Real-Time Feed Service.............................................................................................................. 2-30

Content Service ........................................................................................................................... 2-30

Broadcast Data Service............................................................................................................... 2-31

Scheduler Service........................................................................................................................ 2-31

NVOD Exporter Service............................................................................................................. 2-31

Networking in the OVS System..................................................................................................... 2-31

PSTN............................................................................................................................................. 2-32

LAN .............................................................................................................................................. 2-32

Ethernet................................................................................................................................. 2-33

Packets............................................................................................................................ 2-33

Bus/Broadcast Topology ............................................................................................ 2-33

Best-Effort Delivery...................................................................................................... 2-34

Demands of Video on LANs.............................................................................................. 2-34

Broadband Network................................................................................................................... 2-35

Index

vi

Figures

1–1 Traditional digital video vs. streamed digital video........................................................ 1-3

1–2 Oracle Network Computing Architecture......................................................................... 1-6

1–3 Logical content assembled to create a single cartoon show.......................................... 1-10

1–4 A basic video round trip..................................................................................................... 1-16

1–5 Typical ATM network for the broadband delivery environment................................ 1-17

1–6 An enterprise (Switched Ethernet) OVS system............................................................. 1-18

2–1 Logical content and physical content................................................................................. 2-5

2–2 A stripe.................................................................................................................................... 2-7

2–3 A striped volume................................................................................................................... 2-8

2–4 A RAID stripe......................................................................................................................... 2-9

2–5 A RAID set with parity stripes............................................................................................ 2-9

2–6 MDS Volume Showing Space Allocations....................................................................... 2-11

2–7 Remote file transfer to MDS through MDS FTP server ................................................. 2-13

2–8 OVS system hardware........................................................................................................ 2-20

2–9 Communication in a symmetric network........................................................................ 2-22

2–10 Communication in an asymmetric network.................................................................... 2-23

2–11 An OVS system round trip................................................................................................. 2-24

2–12 Components of Oracle Video Server and Oracle Media Net........................................ 2-25

vii

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Send Us Your Comments

Introducing Oracle Video Server, Release 3.0

Part No. A53956-02

Oracle Corporation welcomes your comments and suggestions on the quality and usefulness of this
publication. Your input is an important part of the information used for revision.

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ix

x

Preface

Introducing Oracle Video Server provides basic conceptual information about the
Oracle Video Server system. This tour is not a technical explanation of how the
software works, but an overview of the basic concepts behind the Oracle Video
Server system.

Read this book before you:

■ install the Oracle Video Server as described in your Oracle Video Server

Installation Guide, or

■ start and operate it as described in your Oracle Video Server Administrator's

Guide and Command Reference

The Oracle Video Server system includes these Oracle software products:

■ Oracle Video Server

■ Oracle Media Net

■ Oracle Video Client

■ Oracle Video Server Manager

This preface discusses:

■ this document’s intended audience

■ the document’s organization

■ other documents related to the Oracle Video Server system

xi

Audience and Organization of This Document

This document is divided into two chapters, intended for slightly different
audiences:

The first chapter presents a general conceptual overview and discussion of video
servers and the benefits they can offer you, as well as some of the advantages
afforded by Oracle’s unique video server implementation. This part is intended for
anyone who would like to learn more about the Oracle Video Server and its
capabilities.

The second chapter presents Oracle Video Server architectural details, and is
intended for OVS system administrators and multimedia application developers.

Related Documents

See the Oracle Video Server Road Map for a list of related documents.

Conventions

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xii

Your Comments Are Welcome

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xiii

xiv

This chapter is intended to introduce you to streamed digital video and video
servers in general, as well as the advantages offered by Oracle Corporation’s
unique implementation of video server technology.

While this chapter deals primarily with higher-level conceptual information, it also
presents enough details of video server architecture to understand the technology
and its capabilities.

What Is Streamed Digital Video?

If you have purchased a digital versatile disk (DVD) of a favorite movie, you’re
already familiar with digital storage and delivery of multimedia content. When the
producers record the laser disc, the information is interpreted and encoded
digitally, then this digital representation is recorded onto the disc. When you play
the laser disc, this digital representation is then decoded, and the result is the video
display that you see.

1

Concepts

Streamed digital video works in much the same way as the digital video you’ve
already used: the video is initially recorded in either traditional analog (unbroken,
continuously varying representation) formats or directly into a digital format. If the
original video is in a traditional format such as videotape, it is then encoded into a
digital format that can be stored on disks and decoded for playback.

Streamed video, however, is fed from a server computer with large storage and
delivery capabilities to a client machine that decodes and displays the streamed
video as it arrives. This eliminates the need for the video to physically reside either
on a playback medium (such as the laser disc) or locally on the machine that
displays the video.

Concepts 1-1

What Is Streamed Digital Video?

How Is Streamed Video Better than Traditional Media?

Streamed video can present several advantages over such traditional media as film
and videotape: like the video on a laser disc, streamed digital video does not
degrade or “wear out” from repeated usage. It remains in original condition until it
is explicitly deleted, modified, or overwritten.

Streaming video over a network also affords a high degree of portability. Unlike the
laser disc, streamed digital video does not require that you physically move the
storage medium with the display mechanism. The client machine need only have
network access to the server machine where the videos are stored.

Digital video is also available as downloaded files, but these files present many of
the same disadvantages as traditional storage media:

■ You must download the entire file before you can view any of the file. In

contrast, you can begin viewing streamed video as soon as the beginning of the
stream reaches the client machine.

■ The local machine must provide enough storage space to contain the entire

downloaded video file. Streamed video requires that the client machine
provide only enough capacity to store and display the video portion being
delivered and viewed (and perhaps a small buffer to provide error-recovery
capability).

More than this, though, streamed digital video is scalable. Many people can view
the same video—not just multiple copies of the same movie title—at very nearly
the same time. The difference in these delivery mechanisms is illustrated in

Figure 1–1.

1-2 Introducing Oracle Video Server

What Is Streamed Digital Video?

Figure 1–1 Traditional digital video vs. streamed digital video

Traditional digital-video media such as
laser discs operate in a “spiral” fashion.
The medium supports only one viewer
at a time; use then “spirals” to the next
viewer, back to disc storage, to the third
viewer, and so on. Each viewer has the

entire

video during viewing, and it is

unavailable to any other viewer.

Streamed digital-video media delivers
the video as a series of small pieces. As
soon one small piece of video has been
sent to one viewer, that piece is
available to be sent to another. Thus,
streamed digital video can
simultaneously serve many viewers.

This important feature of streamed digital video and video server systems is called
video-on-demand, and it means that you can configure the video server to enable
your clients to watch what they want to when they want to, choosing any title that
has been digitized and stored for delivery.

Another way to make streamed digital video available to clients is to schedule it.
An administrator can schedule delivery of a specific video at a specific time on a
specific channel and customers can tune in and watch it. Near video-on-demand
(NVOD) is one application of scheduling in which the administrator schedules
delivery of a video to begin automatically every few minutes on a different
channel. For example, you might schedule “Marvin’s Room” to begin at 8:00 p.m.,
and every 15 minutes thereafter, until midnight. If customers miss the 8:00 show or
have to pause in the middle of the movie, they can wait just a few minutes, and
tune to the appropriate channel to see or resume the movie.

Concepts 1-3

What Is a Digital Video Server?

Video-on-demand and scheduled video are possible because the digital data itself
is stored as a series of stripes, typically of 32k or 64k each, with the stripes
distributed over multiple disks. Depending on the encoded bit rate, a single stripe
on a disk might represent several seconds of video time. As soon as the information
in the stripe has been sent to one client machine, the stripe can be sent to another,
so many different parts of the file can be read simultaneously, and a single copy of
a video can serve many users concurrently.

Striping also enables a sophisticated backup-and-recovery system known as RAID
(Redundant Arrays of Inexpensive Disks) Protection. With RAID, video can still

be delivered in the event of a disk failure. RAID only needs to recover a single
stripe, rather than an entire video, so the server doesn’t need to duplicate storage
space for each video, and that means that more space can be devoted to the videos
themselves.

You can learn more about striping and RAID in Chapter 2.

What Is a Digital Video Server?

Digital-video files can be very large. A 2-hour video in an uncompressed format
may require several hundred gigabytes of storage space. So before files are stored,
they are compressed. The compressed file size depends on the codec (compression/
decompression software) and the compression rate you choose, however the same
video encoded in the MPEG (Motion Pictures Experts Group) format at 1.5 Mbps
still requires about 2 gigabytes.

Because the amount of digital information is so large, digital video generally
demands large storage and delivery capacity. Several movie titles or customer
presentations will require multiple gigabytes of storage. For this reason, it’s not
practical to store these videos in the same places they’ll be viewed, such as:

■ desktop computers or laptop computers connected to a network

■ NC (network computing) devices that rely on a network connection and do not

include their own storage space, or

■ traditional television sets with a set-top box to enable viewing of digital video

This is where a video server comes in. A server machine is designed to offer the
storage and throughput capacities needed for timely and reliable delivery of digital
video. In turn, this means that you need not find storage for every video you want
to view on your desktop computer --- which would leave little room for anything
else!

1-4 Introducing Oracle Video Server

What is the Oracle Video Server?

The Oracle Video Server (OVS) system is a unique implementation of video server
technology for networked computers which store, manage, deliver, and display
digital multimedia data (real-time, full-screen video and high-fidelity audio) on
demand. OVS is supported on a variety of server platforms and can scale to serve
many thousand concurrent users.

This section is not intended to present a detailed explanation of the OVS
functionality, it provides a basic understanding of how the pieces of this system fit
together and relate to one another.

OVS within the Network Computing Architecture (NCA)

The OVS system is fully compliant with Oracle’s Network Computing Architecture
(NCA). NCA affords multiple computing advantages, including a “thin-client”
architecture that requires minimal data storage space on the client machine.

Similarly, the Network Computer (NC) client presents high levels of security and
error recovery; users need only use any NC client machine to log onto the NC
server. They can then restore access to any applications and data that may have
been lost because of power outage, flood, or any other damage to the client
machine.

What Is a Digital Video Server?

Because of its thin-client nature, an NC client machine is also very affordable to
purchase, deploy, and maintain.

Figure 1–2 shows OVS in the NC environment, a scalable, object-oriented

architecture, which consists of three tiers and three layers.

Concepts 1-5

What Is a Digital Video Server?

Figure 1–2 Oracle Network Computing Architecture

Tier 1: Client

There are two client components provided as part of the OVS system:

Oracle Video Client: The Oracle Video Client (OVC) software allows you to
develop interactive, video-based multimedia applications for such uses as
computer-based training (CBT), interactive kiosks, corporate repositories, and Web
sites. The OVC software provides several tools to help you build and view client
video applications. For more information about the OVC, see the Oracle Video Client

Developer’s Guide.

Oracle Video Server Manager: The Oracle Video Server Manager (VSM) is a Java
application that provides management-console client machines with point-and­click control over OVS services, clients, and content. (VSM need not be installed on
every client machine.) For more information about the VSM, see Beyond the Basics
on page 1–20 of this document, and Getting Started with Oracle Video Server Manager.

Tier 2: Application Server

The Application Server tier consists of the Oracle Video Server (OVS). The OVS
functions as the application server in this environment, receiving and processing
requests for digital video, then delivering the digital video content to the client
device.

1-6 Introducing Oracle Video Server

What is a Digital Video Client?

Tier 3: Data Server

The Data Server tier contains the target services which the client needs to access to
get application-specific data. In the OVS system environment, the Data Server tier
consists of the Oracle database (optional). A database is a reliable repository for
persistent storage of structured data. The OVS system can use the Oracle database
to write and query database tables associated with OVS processes, including logical
content, clips, and schedules.

Server Layer

The Server Layer provides the basic functionality for each tier.

Cartridge Layer

The Cartridge Layer provides programmatic functionality for the Server Layer of
each tier.

Communication Layer

The Communication Layer provides communication between servers, cartridges,
and tiers.

What is a Digital Video Client?

If digital video is so large that it must be stored on, and delivered from, a video
server, how do you actually obtain and view the video information in the stored
digital video? The video client machine is responsible for obtaining, decoding, and
displaying the video stored on the server.

Most commonly, the client machine requests the video from the server. In a video­on-demand configuration, video delivery is always a result of requests from the
client; the server does not send digital video content until specifically requested to
do so. The video client then uses either software or hardware to decode the digital
video it requests from the server, and displays that video for the viewer. (In a
scheduled video system, the client does not explicitly request video delivery, since
the delivery schedule has already been established.)

The client does not store the video it displays. Storage and delivery are left to the
server machines, which are large and fast enough to handle the demands of
delivering large amounts of video data. The client requests, receives, and displays
the digital video but does not retain that data—once the digital video data has been
displayed, it no longer exists on the client machine. This means that the client
machine needs only the relatively small amount of system resources necessary to
store and operate the client software, not the digital video itself.

Concepts 1-7

What Are the Challenges of Digital Video?

Customizing the Video Client

The Oracle Video Client can do more than simply request and display digital video.
Its true power lies in its ability to act as a platform that enables you to develop
completely customized video applications for use in computer-based training,
information kiosks, Web sites, and corporate information repositories.

The OVC software comprises a variety of components, each extensible and
customizable, including:

■ Java native classes and a Java player applet, to afford complete consistency and

portability across a variety of operating platforms, such as Microsoft Windows
and various “flavors” of the UNIX operating system. Use of a Java-based video
client also eliminates the need for an installed HTML browser on the target
platform. Additionally, a Java-based client implementation enables smooth
integration and use on Java-based devices such as NCs and set-top boxes.

■ Web Plug-in, for use under a browser in HTML pages.

■ ActiveX control, to integrate the video client into applications designed to

operate in the Microsoft Windows 95 or Windows NT operating systems.

Developers can then deploy the base video client on various machines, using these
“extensions” as the means of integrating the client’s functionality.

What Are the Challenges of Digital Video?

Broadly speaking, the challenge of streamed of digital video is to

1. retrieve large encoded content files from storage,

2. stream these files at high delivery rates across a network that may be

unreliable, and then

3. reassemble, decode and display the streamed content on a client device.

Although the particular challenges of implementing digital video will vary
depending on the environment (broadband, enterprise, or Internet), some of these
challenges are common to all environments. For example, latencies in delivering
data over a network might be acceptable or even unnoticeable in applications such
as word processors or spreadsheets, which are not isochronous or time-sensitive.
Such latencies are extremely noticeable in time-dependent applications such as
video, and show up in the form of glitches such as:

■ misaligned or non-corresponding parts of the video screen

■ some (or all) parts of the screen stop moving

1-8 Introducing Oracle Video Server

■ audio and video are not synchronized

■ the screen is blank for short instances of time

The Oracle Video Server system anticipates these challenges and provides effective
high-level tools to address them. For example, OVS uses several means of ensuring
that your digital video delivery is reliable and won’t be interrupted in the event of
a failed disk or a bad video stripe. In addition to RAID (Redundant Arrays of

Inexpensive Disks) Protection, OVS offers the ability to create Spare Disks

(physical storage space into which you can temporarily transfer content in the
event of a disk failure) and use hot-swapping (a technique to transfer digital-video
data to a spare disk without bringing down the video server system or losing video
service).

How Is Digital Video Used?

You can use Oracle Video Server to incorporate digital video into a variety of
applications, such as interactive training-on-demand, product announcements,
CEO messages, point-of-sale kiosks, web sites, corporate repositories, pay-per-view
television and multimedia catalogs. These multimedia applications can provide
your company with competitive advantages which dramatically improve
productivity while reducing costs.

How Is Digital Video Used?

This section describes some of the interesting ways in which you can use OVS.

Clips and Logical Content

When commercial video subscribers request a “feature” video, the video they
actually see will probably also contain advertisements for available products and
services. There may also be previews of other movies, concerts, and events soon to
be available on digital video.

Each of these short segments is known as a clip. The OVS enables system
administrators to assemble these clips as they see fit, then label the assembled clips
and videos with a single title, to make retrieval and delivery easier. Because these
clips do not actually need to physically be assembled into a single file, but are
accessed from their physical locations by OVS’s internal logic, they are referred to
collectively as Logical Content. Much as beads can be strung together in many
different combinations to create a single unified piece of jewelry, logical content
clips are “strung together” to create a single logical content title, or a single unified
stream of digital video.

Concepts 1-9

How Is Digital Video Used?

This concept is also the way you construct a playlist on your home CD player. For
example, if you have three CDs loaded into your player, you may find that you like
the first four tracks of the first disc (but not the fifth track), all of the tracks on the
second disc, and only the eighth track of the third disc. You can program your
player to play only these tracks, in any sequence you choose, and give this
assemblage a single name to be stored in the player’s memory for easy retrieval.
Logical content within digital video files works in nearly the same way, except that
a database is required to track all of the many possible combinations of video clips.

Figure 1–3 shows one possible way in which logical content might be used to

assemble a children’s cartoon show; the basic process will work the same way
when any video subscriber chooses a video using logical content capabilities.

Figure 1–3 Logical content assembled to create a single cartoon show

You can also write OVS applications that define logical content titles dynamically.
These applications can customize logical content based on users’ interests and
viewing history. For example, the application could program the advertisements
that show during a movie based on the interests of the viewers.

1-10 Introducing Oracle Video Server

You can learn more about logical content, clips, and the differences between the
video server computer (where OVS resides) and the database server computer
(where an Oracle database stores logical content definitions) in Chapter 2.

Real-Time Feeds

Some commercial video providers also offer Real-Time Feeds. In this situation,
special encoders are used to record, encode, and begin streaming digital video of an
event as that event occurs—in so-called “real time.” News channels, stock updates,
sports, corporate events, or other services that depend on up-to-the-minute
accuracy and timeliness of information can use One-Step Encoding (digital video
is encoded as it is recorded) and Continuous Real-Time Feeds to ensure their
customers get the latest information via digital video, because the viewer sees the
event nearly as it happens, the only delay being the minimal time necessary to
encode and deliver each moment of the event. Viewers can also pause, restart,
rewind, and fast forward the video up to the current “live” point.

Where is Digital Video Used?

Where is Digital Video Used?

Broadband

Digital video can be used in many environments. This section describes some
example, divided into the broad categories broadband, enterprise, and Internet.

The broadband environment is characterized by high-speed delivery of complex
video data, such as would be required by full-screen, full-motion video. This data
need not necessarily represent long videos (for example, a home-shopping segment
might be 2-3 minutes or less), but will include a great deal of digital-video
information.

Typically, this environment requires the use of a dedicated set-top box, a special
receiving and decoding device attached to a display such as a television monitor.
Examples of broadband usage would include:

■ Subscription-service delivery of a digitally recorded event such as a blacked-

out athletic game

■ Movies, concerts, Broadway shows, or other events delivered on demand

■ News on demand

■ Product and service directories

■ Distance learning

Concepts 1-11

Where is Digital Video Used?

■ Home shopping

■ Home financial services

■ Medical diagnostics

Asynchronous Transfer Mode (ATM)

Broadband deployment of streamed digital video often uses the Asynchronous
Transfer Mode (ATM) networking protocol for video delivery. ATM provides a

reliable mechanism for high-speed delivery of large amounts of highly complex
data, using fixed-size delivery packets called cells. Because of its switched,
connection-oriented nature and its fixed cell size of 53 bytes, ATM is an inherently
reliable, scalable networking technology.

ATM can offer several advantages over other networking protocols, including:

■ scalability, to work at different speeds and on different media

■ open-ended growth paths, since ATM is not tied to any physical medium or

speed

■ a single network for delivery of voice, data, and video, thereby improving

efficiency and manageability

■ compatibility with existing physical networks (because ATM is not dependent

on a specific type of physical transport)

In some cases the ATM network is used only for delivery of the video data itself,
and another network is used to deliver system messages between the client and
server. The second network often has less bandwidth than the video network; for
example, using Internet Protocol (IP) over a telephone line.

Digital Subscriber Line (DSL) Transport Systems

One emerging way of delivering video is through DSL (Digital Subscriber Line)
transport systems. DSL was originally intended by telephone companies as a way
to deliver both television and telephone service over existing copper telephone
lines. Using the same copper wires on which much existing telephone service is
based, DSL can provide data access and downloading up to 50 times faster than a

28.8 Kbps modem.
DSL is actually a continuum of a variety of transport systems that can carry about 1

to 6 Mbps. In general, the faster the DSL, the shorter the distance it can reliably
cover. The fastest DSLs can cover only a few miles; the slowest can cover farther.

1-12 Introducing Oracle Video Server

Enterprise

Where is Digital Video Used?

DSLs include:

■ ADSL (Asymmetric DSL) — called “asymmetric” because the connection from

service provider to client delivers large amounts of data at high rates, but the
connection from client to service provider operates at a much lower rate.

■ HDSL (High-bitrate DSL) — currently the only widely deployed DSL and

essentially a replacement for traditional T1 service. T1 lines carry 1.5 Mbps and
have been available for many years, but require technicians to tune them to
optimum performance. HDSL modems can handle marginal connections with
little problem, so they are often much less expensive to install and operate.

Telephone companies are developing new DSLs for future use.

In an enterprise environment, needs are geared toward the particular company (or
“enterprise”) implementing the video solution. Content may still be as large as in
broadband environments, but viewers are served over a corporate LAN (using
switched Ethernet networking), WAN, or intranet.

Switched Ethernet, like ATM, is a highly scalable networking protocol capable of
delivering very large amounts of data at high speeds. Additionally, an Ethernet
network can, when needed, be migrated to an ATM network topography.

Switched Ethernet, as opposed to unswitched or shared Ethernet, helps prevent
“bottlenecks” or slow-downs in network operation caused by multiple users
needing to read every data packet to determine which packets apply to which
clients. Likewise, switched Ethernet is a full-duplex protocol, meaning that each
hub can simultaneously send and receive, unlike other half-duplex protocols that
do only one or the other at one time. Switched Ethernet allocates and reserves
necessary bandwidth for each user connecting to the network, so latencies in
delivery of data over the network are minimized or eliminated.

Examples of enterprise usage of Oracle Video Server, over switched Ethernet,
would include:

■ Delivery of corporate training videos at a time convenient to the employee or

least disruptive to work schedules, rather than as a single scheduled event with
many employees in a single room at a time.

■ Corporate announcements from upper management or the Board of Directors.

Concepts 1-13

Where is Digital Video Used?

■ Information stored in a “corporate repository” and available for retrieval as

needed—for example, detailed step-by-step instructions for enrolling in your
company’s 401(k) program, instructions for installing a piece of equipment, or
an introductory tour of the new cafeteria.

Internet

The Internet environment is typically oriented toward delivery of digital video
over public Internet pages. Most people still connect to the Internet via modem,
and this environment is often referred to as “low-bitrate” because of the constraints
imposed by modems with a relatively slow rate of delivery—a “low bit rate.”
Although many newer modems boast speeds that seem very fast in comparison to
older modems, they are still extremely slow compared to the delivery rates of a
broadband environment, and this slower delivery rate must be taken into account
when planning digital-video delivery for this environment.

Internet users who connect via a modem will connect with their Internet Service
Provider (ISP), who provides access to the OVS through the Internet. Through a
single connection, the client communicates with the ISP using PPP (Point-to-Point
Protocol) and with the OVS using either TCP/IP or UDP/IP (Transmission Control
Protocol or User Datagram Protocol/Internet Protocol).

Because of its increasing availability and affordability, DSL has also become a
popular way to access the Internet. Although high-bitrate transports like DSL are
avialable, as the administrator of a video-based Web site, you should plan for the
slowest transport system that is likely to access your site, rather than relying on
your clients to have a faster one.

There are many innovative uses for Internet-based delivery of video, including:

■ Advertising. Many commercial locations now have Web sites that feature

informative digital video to acquaint you with their product.

■ News. You can subscribe to news-delivery Web sites that offer not only still

photos (as in an “online newspaper”) but full-motion digital video of breaking
stories.

■ Site tours. Some sites, especially those for large academic institutions, are large

and complex enough that they offer video orientation to the Internet site, the
institution itself, or both.

1-14 Introducing Oracle Video Server

Putting It Together: The Video Round Trip

Putting It T ogether: The Video Round T rip

So how does a request from the client machine for digital video result in that video
being delivered and displayed to the viewer? This section illustrates that process,
known as the video round trip, by showing typical configurations in each of three
video environments: broadband, enterprise, and Internet.

You can learn more about streamed-video round trips in the online Oracle Video
Server Manager Quick Tour.

All Environments

At its most fundamental, a streamed-video round trip functions as shown in

Figure 1–4 and described as follows:

1. Client Tier The video client sends necessary configuration information (and, in a
VOD situation, the request for video).

The client device can be:

■ A set-top box connected to a television set or monitor and to a public or a

private network. This is a typical client device for use in a broadband delivery
environment.

■ An NC (Network Computer) connected to a network. Through the network,

the Network Computer accesses an NC server and the OVS.

■ A PC (Personal Computer) connected to a network.

2. Network The network receives, processes, and forwards information between
the client device and OVS. This portion of the video round trip is the part that
primarily defines the environment as broadband, enterprise, or Internet.

3. Application Server Tier Oracle Video Server receives video requests, processes
them, and (if necessary) communicates with the video-database server to obtain
digital-video titles and files.

4. Data Server Tier (Optional) The video database maintains metadata concerning
the actual digital video files, accesses and delivers video-file information to OVS.

Concepts 1-15

Putting It Together: The Video Round Trip

Figure 1–4 A basic video round trip

Tier 1: Client

■ Set-top box

■ Network Computer

■ Personal Computer

Network: This portion of

the video round trip varies
most, and is the primary
determinant of the video
delivery environment.

NETWORK:

ATM
Switched
Ethernet

N

ETWORK:

UDP/TCP

ATM
SWITCHED
ETHERNET
UDP/TCP
HTTP

Tier 2: OVS acts

as the Application
Server Tier.

Tier 3: An

optional
dedicated
database server
stores metadata
(administrative
information about
content files).

Scenario 1: Broadband Environment

The broadband environment is characterized by delivery of large amounts of
digital video data at very high rates to dedicated set-top devices that receive and
decode the digital video. Video is typically shown full-screen and full-motion.

Figure 1–5 shows an example of a network configuration using Asynchronous
Transfer Mode (ATM) in a broadband delivery environment. The network itself has

been somewhat simplified, to show a typical configuration; actual broadband
deployment might involve many more variables in terms of particular hardware
used, the number of neighborhood hubs, and the type and number of ATM
multiplexers.

1-16 Introducing Oracle Video Server

Putting It Together: The Video Round Trip

Figure 1–5 Typical ATM network for the broadband delivery environment

Client

Device

To/From

HFC
(Hybrid-Fiber Coaxial)
cable

Individual Homes

add’l clients

Up to 622 Mbits/sec

Neighborhood
or Area

Region or
Metropolitan Area

OVS

Video Service
Provider

Neighborhood
Hub

ATM
Switch

To/From

add’l hubs

To/From add’l

switches

Database

1. In an ATM
environment, the
neighborhood hub
receives messages
from, and delivers
video to, the client
device. The hub has
the IP address of the
client, to ensure
proper delivery.

2. The neighborhood
interfaces with an ATM
switch serving an area
or metropolitan region
(several hubs).

3. The switch forwards
client messages to
OVS (which
communicates with
the database server),
and delivers streamed
video coming from the
server.

Concepts 1-17

Putting It Together: The Video Round Trip

Scenario 2: Enterprise Environment

In the enterprise environment, the processes of requesting titles and delivering
digital video are much the same as in the broadband environment (for details, see

Scenario 1: Broadband Environment on page 1–16), except that:

■ An enterprise environment does not typically schedule video broadcast.

Instead, it will usually make digital videos available as requested from client
machines.

■ The network communication layer, rather than consisting of a dedicated high-

speed broadband network, will instead consist of a corporate-wide LAN (Local
Area Network) or WAN (Wide Area Network). This layer might use such
communication protocols as Switched Ethernet, CDDI, or FDDI (Copper or
Fiber Data Distributed Interface).

A Switched Ethernet topology provides optimal throughput and reliability in
this environment. Figure 1–6 shows a typical configuration for the Switched
Ethernet network used for video delivery in an enterprise environment. See

Enterprise on page 1–13 for more information on using Switched Ethernet in an

OVS system.

Figure 1–6 An enterprise (Switched Ethernet) OVS system

Up to 155 Mbits/sec

To/From add’l
Ethernet hubs

Up to 155 Mbits/sec

OVS

Database Server

To/From LAN,
routers, and
add’l Ethernet hubs

C

LIENT DEVICES:

■PCs

■NCs

■Workstations

NETWORK:

Switched
Ethernet hubs

ERVERS:

S

OVS and
Database

1-18 Introducing Oracle Video Server

Putting It Together: The Video Round Trip

■ No “membership subscription” is required to the corporate network. The client

device is a computer which is also used for other purposes, rather than a set­top box. The delivery network is also not solely dedicated to video.

■ The client application used for video display might be deployed as part of

another application such as an e-mail or groupware package. For example, you
might choose to deploy a video client as an ActiveX component in a Windows­based application you are developing, to provide “one-on-one” video training
to the application’s new users. Or, you might use the Web plug-in client to
enable viewers to browse corporate intranet pages and view the videos those
pages reference.

■ Depending on the bandwidth available, video may be shown full-screen or in a

window on the PC, and at various frame rates.

■ Logical content is available (assuming a database is used to store such

content), and the nature of it is tailored to corporate needs. For example, a
digital video introducing a new product might begin with a clip of the
company CEO giving a short speech. For a description of the capabilities of
logical content, see Clips and Logical Content on page 1–9.

Scenario 3: Internet Environment

In the Internet environment, the process of delivering digital video is much the
same as in the broadband environment (for details, see Scenario 1: Broadband

Environment on page 1–16), except that:

■ The network communication layer, rather than consisting of a dedicated high-

speed broadband network, will instead consist of PSTN (Public Switched
Telephone Network) over the publicly accessible Internet, or another protocol if
the Internet is accessed from within a corporate-specific intranet. Over the
Internet, this layer uses such communication protocols as TCP (Transmission
Control Protocol) or UDP (User Datagram Protocol).

■ The client device is a PC, NC, or set-top box running an HTML browser or

applications written in the Java programming language.

■ The client application used for video display might be deployed as a plug-in

(an extension) on the associated HTML (Hypertext Markup Language, the
basic language of Internet pages) page, or as a Java application or applet.

■ Video is generally viewed in a small window with quality reflecting the

bandwidth of the connection.

Concepts 1-19

Beyond the Basics

You can learn more about designing video-delivery systems for the Internet
environment in the Oracle Video Server’s Administrator’s Guide and Command
Reference.

Beyond the Basics

Maintaining an OVS System

The OVS provides powerful and flexible tools for maintaining the video-delivery
system. These tools include:

■ Oracle Video Server Manager (VSM). VSM is a Java-based management tool

that provides a graphical means of viewing and managing your OVS system. It
enables you to perform a variety of system-maintenance and content­management tasks, including:

■ Starting and stopping the OVS

■ Adding, removing, and updating content files within your digital-video

storage

■ Checking and editing the status of clips making up your various logical

content titles

■ Registering new or existing content files, so that OVS recognizes them and

allocates necessary resources for storing and delivering them

■ Defragmenting MDS volumes to minimize unusable empty disk space

To learn more about VSM, begin with Getting Started with Oracle Video Server
Manager, then continue with the online Oracle Video Server Manager Quick Tour

and Help system.

■ Command-line utilities that enhance and extend VSM capabilities. Some tasks

require extensive personalization or customization, and OVS includes a library
of command-line utilities to perform tasks that lie outside the usual domain of
VSM.

1-20 Introducing Oracle Video Server

Creating Applications

One of the greatest strengths of OVS is its extensibility; you can create custom-built
versions of both the server and the client portions of this digital-video system.

The Oracle Video Client (OVC) is designed with customization in mind. While this
portion of the OVS system serves basic digital video display needs out of the box, it
also offers the ability to customize and create a wide variety of tailored client
applications. The video client is available, and provides for creation of custom
applications, in an assortment of platforms, including:

■ Platform-native versions for Microsoft Windows 95 and Microsoft Windows NT

■ Java- and JavaScript-based versions for deployment on a variety of operating

systems

■ a plug-in for use in Web pages

You can learn more about the OVC and its extensibility in the Oracle Video Client
Developer’s Guide.

The server is designed to provide an out-of-the-box solution to your delivery needs
for digital video. However, you can tailor it to exactly suit your needs, by using the
rich application programming interfaces (APIs) included with the OVS software.
For example, you could build a client application for your set-top box or a real-time
encoder. To learn more about using the OVS APIs, see the Oracle Video Server

Developer’s Guide.

Beyond the Basics

Concepts 1-21

Beyond the Basics

1-22 Introducing Oracle Video Server

2

System Arc hitecture

This chapter is an overview of the architecture used in the Oracle Video Server
(OVS) system. The information in this chapter is intended to expand on the basic
digital-video overview provided in Chapter 1, “Concepts”. If you are not familiar
with basic concepts of streamed digital video, read Chapter 1 to learn about digital
video, video servers, and the OVS system, before reading this chapter to gain in­depth understanding of the system architecture.

The chapter describes these Oracle components that are used in the OVS system:

■ Oracle Video Server (OVS)

■ Oracle Video Server Manager (VSM)

■ Oracle Media Net

■ Oracle Video Client (OVC)

It also describes:

■ OVS System Hardware and Network Architecture

■ How the OVS System Communicates

■ Components of Oracle Video Server and Oracle Media Net

■ Networking in the OVS System

System Architecture 2-1

Oracle Video Server (OVS)

Oracle Video Server (OVS)

The Oracle Video Server (OVS) is a scalable video software engine that stores video
on a video server computer and can deliver the video to multiple concurrent clients
in real time. This chapter uses the term video to refer to any data streamed in real
time, including digitized video and/or audio.

This section describes these OVS features and benefits:

■ Content

■ Storage

■ Delivery

■ Network

Content

The video that the OVS stores and delivers to clients is called content. The OVS
stores content in these forms:

■ Physical Content — the actual physical files containing multimedia data

■ Logical Content — logical representations of the physical data that you can

define to customize the multimedia data your clients can request

Physical Content

Physical video content files are created from actual video through a process called
encoding performed by a third-party encoding software or hardware called a codec
that is not part of the OVS. To create content, the encoder uses these formats:

■ The way in which an encoder compresses video frames so they use less space is

called a compression format or a codec.

■ The way in which an encoder multiplexes, or puts together, video and audio is

called a container or mux format.

Compression Formats The OVS can stream many compression formats including:

■ MPEG (Motion Pictures Experts Group)

■ Iterated Systems ClearVideo

■ Radius CinePak

■ Intel Indeo

■ Motion JPEG (Joint Photographic Experts Group)

2-2 Introducing Oracle Video Server

Oracle Video Server (OVS)

MPEG (Motion Pictures Experts Group) The OVS supports these compression
formats defined by MPEG:

■ MPEG-1 video

■ MPEG-2 video

■ MPEG audio

MPEG formats provide full-motion (up to 60 frames per second), full-screen video
with high fidelity/stereo audio playback.

By taking advantage of redundancies among frames in a video sequence, MPEG
formats provide a storage compression ratio of 100 to 1 over storing each frame
individually, reducing the amount of disk space required to store video.

Container (Mux) Formats The OVS supports these container, or multipexed
(mux), formats:

■ MPEG-1 System

■ MPEG-2 Transport

■ RKF (Raw Key Frame) Container Formats such as:

■ AVI

■ WAV

MPEG-1 System and MPEG-2 Transport Table 2–1 shows combinations of MPEG

codecs and container formats in which the OVS can deliver video.

Table 2–1 MPEG Codecs and container formats

Container Formats

MPEG-1 System MPEG-2 Transport

MPEG-1 ✓✓

Codecs

MPEG-2 ✓

System Architecture 2-3

Oracle Video Server (OVS)

RKF (Raw Key Frame) Container Formats The OVS can also deliver video files
in any container format meeting the raw keyframe criteria:

■ stateless — all the data for displaying the picture in a video frame is contained

entirely in that frame, rather than in any previous frames

■ contiguous — all the data for a frame is stored together in the video file and no

other data mixed with it

OVS supports delivering files in the RKF formats AVI (Audio Visual Interleave)
and WAV (Wavefore audio-only) to Oracle Video Client by converting them to OSF
(Oracle Streaming Format). OSF is an RKF format designed by Oracle Corporation
for efficient delivery of content that has not been optimized for streaming.

Tag Files The OVS creates and stores a tag file associated with each content file.
Tag files contain metadata, information the OVS needs to perform rate control
sucha as pausing and blind seeking and (on supported clients) visual fast forward
and rewind. If a client application requests a rate control operation on a content file,
the OVS reads the associated tag file to determine which parts of the content file to
deliver to the client.

When you use Oracle Video Server Manager (VSM) to load a content file into the
OVS, VSM automatically creates a tag file for the content file. The OVS also
provides utilities to:

■ create tag files for MPEG content files

■ convert AVI and WAV files to OSF and create tag files for them

■ create empty tag files for playing video without rate control in formats other

than MPEG, OSF, and full raw keyframe formats
The OVS also provides a utility to register existing tag files.
To support rate control for tag files in another compression format that meets the

full raw keyframe criteria, you must provide a tagging utility for the format.
VSM and the provided utilities also register the tag files in the table of contents of

the OVS and in an Oracle database in your OVS system (if you are using one).

One-Step Encoding Making content available on the OVS typically involves
obtaining a complete content file from an encoder, loading the file from tape, and
creating an associated tag file with a tagging utility. Some encoders can encode a
video content file and generate a tag file in real time (while the source video is
playing) through a process called one-step encoding. The OVS can accept and store
content from encoders in one step making new content available in real time.

2-4 Introducing Oracle Video Server

Oracle Video Server (OVS)

Continuous Real-Time Feeds The OVS can store the most recent portion of a

continuous real-time feed, or an endless stream of one-step encoded video. A

continuous real-time feed enables a client to search the most recent portion of

ongoing video, such as the last 12 hours of a 24-hour-a-day news broadcast.

Logical Content

Logical content is a collection of titles, each representing a series of parts of

physical content files. As an administrator, you can define logical content to

customize the multimedia data your clients can request. Figure 2–1 shows how you

can define a logical content title representing a television feature containing

advertisements based on individual physical content files containing the feature

and the advertisement.

Figure 2–1 Logical content and physical content

Logical
Content

Physical
Content

First Half

of Feature

Feature

Tag File

Feature

Second Half

of Feature

Feature with Ads

First Set

of Ads

Ads

Tag File

Ads

Second Set

of Ads

Logical content titles

each representing a series of clips

Clips

each representing a part
of a physical content description

Physical content descriptions

each describing a tag file

Tag files

Physical content files

System Architecture 2-5

Oracle Video Server (OVS)

Whenever you create a tag file for a physical content file, the tagging utility
automatically stores this information in the database:

■ a physical content description of the tag file

■ a clip representing the entire physical content description

■ a logical content title representing the clip

If you as the administrator do not define additional logical content titles and clips
to customize the content your clients can request as in Figure 2–1, clients can only
request the logical content titles for individual physical content files.

Since logical content definitions are stored in a database, defining logical content
does not create new physical content files or modify existing ones.

Storage

The OVS stores physical content in the Oracle MDS (Media Data Store), a real-time
file system for storing and delivering uninterrupted video in real time. This section
describes the MDS.

The OVS optionally stores logical content in an Oracle database. For information on
how Oracle databases store data, see the Oracle Concepts manual.

Real-Time Access

The MDS can tolerate disk errors and variance in disk latency and still provide real­time access to content. The MDS can also deliver video in real time while you are
administering the MDS.

Files

The MDS can store these types of files:

■ video files

■ audio files

■ BLOB (binary large object) files

■ tag files

2-6 Introducing Oracle Video Server

Oracle Video Server (OVS)

Write Consistency The MDS enforces write consistency on all MDS files:

■ A file can be written by only one client at a time.

■ A file cannot be renamed, removed, truncated, or locked into read-only mode

while it is being written.

■ If a process fails while writing to a file, the MDS makes the file available to be

written by other processes after a few minutes.

Volumes

MDS files are stored in MDS volumes — named collections of disks. Each MDS

volume stores files in a flat namespace. The MDS provides quick access to a file

given a unique identifier, such as a filename, but is not meant to be a general

purpose file system with nested hierarchical subdirectories to search and browse.

Logical content provides that level of interaction.

Each volume has a table of contents that lists the files in the volume and their

locations on disk.

Striping Striping means dividing a file into pieces and storing each piece on a

different disk. Striping a file distributes access to the file across many disks, rather

than concentrating it on one, reducing requests for each disk and improving

performance when the file is accessed by many concurrent clients.

A stripe is a portion of a disk reserved for a single piece of a striped file. The size of

a stripe is called a stripe size. The stripe size is the same for every disk in the

volume. Figure 2–2 identifies a single stripe on a disk.

Figure 2–2 A stripe

A Stripe

System Architecture 2-7

Oracle Video Server (OVS)

The MDS supports striping on a volume-by-volume basis. In a striped volume each
file is striped across all the volume’s disks. To write a file to a striped volume, the
MDS writes a stripe on each of the volume’s disks beginning with the first. If the
file requires more space than a single stripe on each disk in the volume, the MDS
writes another stripe to each disk beginning with the first. The MDS continues to
write stripes across all the volume’s disks until the entire file has been written. The
shaded area in Figure 2–3 shows a single stripe on each disk in a volume.

Figure 2–3 A striped volume

Striping is transparent to the user and a striped file appears logically as one
contiguous sequence of bytes.

RAID (Redundant Arrays of Inexpensive Disks) Protection RAID protection
means storing data redundantly so it remains accessible in the event of a disk
failure. The RAID protection implemented for the MDS is similar to hardware­based RAID protection but also guarantees on-time delivery even if a disk or
controller fails. RAID is similar to disk mirroring, but uses less space for redundant
data. Together, striping and RAID offer tremendous performance benefits with a
high degree of reliability.

The MDS supports RAID protection on a volume-by-volume basis. If RAID
protection is enabled for a volume, the disks in the volume are divided into RAID
sets. The number of disks in each RAID set is called the RAID size. The RAID size
must be consistent across all RAID sets in a volume, so the number of disks in a
volume must be a multiple of the RAID size.

2-8 Introducing Oracle Video Server

Oracle Video Server (OVS)

In a striped volume, the set of stripes that have the same logical location on the

disks of a RAID set is called a RAID stripe. Figure 2–4 shows a RAID stripe within

the dotted rectangle.

Figure 2–4 A RAID stripe

The MDS designates one stripe in each RAID stripe to store parity information,

technically the "bitwise exclusive OR" of the other stripes. The disk containing the

parity stripe rotates from one RAID stripe to the next as shown in Figure 2–5.

Figure 2–5 A RAID set with parity stripes

Parity
Data

The amount of data contained in a RAID stripe is:

stripesize x RAIDsize

Since one of the stripes in the RAID stripe stores parity information, the amount of

non-redundant data stored in a RAID stripe is:

stripesize x (RAIDsize–1)

System Architecture 2-9

Oracle Video Server (OVS)

The RAID stripe is the smallest unit of allocation in the MDS.
If a disk fails, the MDS can dynamically reconstruct its data from the other disks in

the RAID set, using the parity information. The reconstruction occurs as the data is
requested and is transparent to the user. You can also rebuild data from a failed
disk onto a new disk with the rebuild utility.

The MDS can tolerate one failed disk in each RAID set and continue to deliver
video without glitches, or disturbances in the video. If there are multiple
concurrent failures in a RAID set, the missing data cannot be reconstructed and the
volume can no longer play video.

Space Allocation When writing a file to a volume, the MDS writes each stripe
sequentially across disks in each RAID set and writes each RAID stripe
sequentially across RAID sets in the volume.

A volume’s table of contents is stored on the first RAID stripes of the first few
RAID sets, depending on how the volume is defined. The MDS begins storing files
in an empty volume with the first RAID stripe on the RAID set after the table of
contents. The MDS writes sequentially across disks in the RAID set, writing one
stripe on each disk. After filling a RAID stripe, the MDS writes sequentially across
the first RAID stripe in the next RAID set, and so on. When the MDS reaches the
last disk in the last RAID set, it returns to the first RAID set and proceeds to write
to the second RAID stripe. The last RAID stripe allocated for the file may not be
completely filled by the file. This space remains empty. To write another file to the
volume, the MDS begins with the first disk in the next RAID set.

The number of stripes taken up by a file depends on the length of the file as
illustrated in Figure 2–6. Each RAID stripe is labeled by the file containing it (A, B,
or C) and the number of the RAID stripe within the file. Note that the figure does
not distinguish data from parity information. All RAID stripes, including the one
containing directory structure information, include an associated parity stripe.

The space allocated for a file may exceed the actual file size by:

(stripesize x (RAIDsize–1))-1

for a 1 byte file.
If a file is deleted from a volume, the MDS can reclaim that file’s space by storing

one or more new files that fit there. The MDS cannot distribute a file over
noncontiguous RAID stripes. The defragmenter utility can make the
noncontiguous empty RAID stripes contiguous.

2-10 Introducing Oracle Video Server

Figure 2–6 MDS Volume Showing Space Allocations

Oracle Video Server (OVS)

B2
B6
C3 C3 C3 C3

A1
B3
B7
C4 C4 C4 C4

A2
B4
C1 C1 C1 C1
C5 C5 C5

B1
B5 B5 B5 B5
C2 C2 C2 C2

B2 B2 B2
B6 B6 B6

A1 A1 A1
B3 B3 B3
B7

A2
B4 B4 B4

B1 B1 B1

Empty

= table of contents
A1 = first RAID stripe of file A
A2 = second RAID stripe of file A
B1 = first RAID stripe of file B
Empty = unused portion of allocated RAID stripe

EmptyEmpty

Empty

Empty

Spare Disks A spare disk is a designated empty disk in a volume onto which

data from a failed disk can be rebuilt. A spare disk is not part of a RAID set. On a

video server computer that does not support hot-swapping disks (replacing disks

while the computer is online), a volume must contain a spare disk to support

rebuilding data while delivering video. Without a spare disk the OVS cannot

deliver video while the failed disk is replaced and rebuilt. Spare disks are

unnecessary on video server computers that support hot-swapping disks.

System Architecture 2-11

Oracle Video Server (OVS)

MDS Utilities

The OVS provides a group of general operating system command line utilities that
allow you to perform standard file operations on files and volumes in the MDS.
More specialized MDS utilities include:

■ tape archival utility—enables you to archive, backup, and retrieve a group of

files to and from a single archive file in tape archive (TAR) format or a sequence

of tapes in an Exabyte stacker

■ defragmenter utility—allows you to defragment volumes to reduce wasted

space without taking the OVS offline

■ rebuild utility—enables you to:

■ replace a failed disk and rebuild data onto the replacement while the MDS

■ rebuild data from a failed disk onto a spare disk from redundantly stored

■ take the OVS offline, replace a failed disk, and rebuild data onto the

delivers video, if your operating system supports hot-swapping disks, or to

data while the MDS plays video, or to

replacement

MDS utilities accept wildcard specifications as general operating system command­line utilities do.

HSM (Hierarchical Storage Management)

The MDS is part of the HSM (hierarchical storage management) supported by the
OVS that stores data in:

• memory (primary storage)

• MDS volumes on disk (secondary storage)

• a tape archive (tertiary storage)

You can store large numbers of files in a tertiary tape archive.

HSM Utilities The OVS provides HSM utilities that enable you to:

■ load files from tertiary storage to the MDS before clients need to access them

■ archive files from the MDS to tertiary storage if clients will not need them for a

period of time, to make room in the MDS for other files

2-12 Introducing Oracle Video Server

Oracle Video Server (OVS)

Remote Access

The MDS is accessible by processes on remote computers as well as on the video

server computer.

The OVS also supports binary file transfer between FTP clients on remote

computers and the MDS. Figure 2–7 shows a direct FTP file transfer from a remote

computer to the MDS.

Figure 2–7 Remote file transfer to MDS through MDS FTP server

Delivery

Remote Computer

remote

FTP

client

remote

file

system

Video Server Computer

Oracle Video Server

host

file

system

MDS
FTP

server

MDS

The alternative, an FTP transfer from the remote computer to the video server

computer host file system and then a transfer to the MDS with an MDS utility,

would require an additional copy operation.

The OVS can deliver a video stream to a client in real time on demand. A stream of

video is played by the client as it is delivered by the OVS, rather than completely

downloaded by the OVS and then played by the client.

Requesting Video

A client can request the OVS play video by requesting it. In a request, a client

identifies video with an asset cookie, which stands for either a logical content title

or a tag file. The client can request a series of asset cookies so that the OVS plays

series of logical content titles or tag files without interruption.

System Architecture 2-13

Oracle Video Server (OVS)

Rate Control

Rate control enables a client to pause, resume, and reposition a video stream. The
OVS supports these rate control functions:

■ Pause—stop the video and maintain its current position

■ Resume—continue to play video from the point at which it was paused

■ Seek forward or backward—jump directly to a later or earlier point in the video

■ Scan forward or backward—visual fast forward or rewind for selected formats

and clients

Real-Time Feeds

The OVS can deliver a real-time feed, or a stream of one-step encoded video as it is
encoded and stored. A client viewing a real-time feed can scan and seek backward
to access any of the encoded video. For example, a client viewing a live sports
event through a real-time feed can replay key points in the event as the event
continues to be encoded and stored.

Scheduled Video

The OVS enables you to schedule a logical content title to begin playing on a
specific network channel at a specific time. Clients can then “tune in” to see the title
they want with no signals required from the client to the OVS. Scheduling enables
you to implement:

■ regularly-scheduled television broadcasting

■ pay-per-view

■ NVOD (near video-on-demand)

NVOD (near video-on-demand) enables a client to view a film from the beginning
at regular intervals (for example, every 15 minutes). By scheduling the same title on
different channels at staggered times, you can enable clients to see the film from the
beginning by tuning to a channel when the film is beginning there. Also, a client
can effectively pause and seek forward and backward in 15-minute increments by
tuning among different channels that began the film at different times.

Looping Content

The OVS can loop, or continuously repeat playback of a logical content title.
Looping content can be useful for displaying a moving logo or for filling the time
between the end of a scheduled film and the beginning of the next with
advertisements or public service announcements.

2-14 Introducing Oracle Video Server

Network

The OVS can deliver data at different bit rates over a wide variety of networks and

protocols. Supported protocols include:

■ UDP (User Datagram Protocol)

■ TCP (Transmission Control Protocol)

■ ATM (Asynchronous Transfer Mode)

■ AAL5 (ATM Adaptation Layer 5)

■ DVB (Digital Video Broadcast)

Oracle Video Server Manager (VSM)

Oracle Video Server Manager (VSM) is an application with a graphical user

interface that monitors and manages the OVS and its clients. VSM enables you as

the administrator to perform tasks including:

■ starting and stopping instances of the OVS

Oracle Video Server Manager (VSM)

■ viewing the status of critical OVS services

■ create and manage logical content titles and clips

■ monitoring:

■ MDS disks and files

■ HSM tertiary storage tapes

■ real-time feeds

■ clients of the OVS

■ defragment MDS volumes

■ loading and registering physical content files

■ scheduling and playing videos

For more information on VSM, see Getting Started with Oracle Video Server Manager.

Graphical User Interface

The VSM application provides a Java-based user interface. It is designed for ease of

use so you as the administrator can effectively manage the OVS system quickly

with minimal training.

System Architecture 2-15

Oracle Media Net

Oracle Media Net

Oracle Media Net is a networking infrastructure that enables the OVS and its
clients to communicate in a distributed computing environment. Using
heterogeneous network protocols, Oracle Media Net enables connectionless
communication among the various OVS system components running on different
platforms. Oracle Media Net is Oracle’s implementation of CORBA (Common
Object Request Broker Architecture), so heterogeneous services programmed in
different languages and distributed over different computers in a network can
communicate without concern for each other’s location or the details in
transporting or converting data among them. CORBA is an open standard for
distributed network objects defined by the OMG (Object Management Group) that
provides the mechanisms by which applications transparently make requests and
receive responses.

Oracle Media Net abstracts the network for the application developer and the
network protocols underlying Oracle Media Net are transparent to the components
using it. You can create an application once and deploy it on many different
platforms without changing its Oracle Media Net calls. Oracle Media Net also
automatically bridges connections across network types, making multiple protocols
in the same network transparent and presents a reliable message service, even if the
underlying network protocols use unreliable messaging.

For complete conceptual information on Oracle Media Net, see the Oracle Media Net
Developer’s Guide.

Clients and Servers

When an application in an Oracle Media Net network needs to perform an
operation that requires resources or functionality not available locally, it requests
that a remote application perform the operation. The requesting application is
called the client and the remote application performing the operation is called the
server.

2-16 Introducing Oracle Video Server

Objects, Interfaces, and Servers

This section briefly defines terms used in a CORBA environment:

■ An object is a means of encapsulating functionality and providing a simple and

consistent interface that defines how clients can use that functionality.

■ An interface defines a named set of related operations. The description of an

object is a set of operations defined in an interface.

■ A server is a single computer process that implements one or more interfaces.

You can define the interfaces for your own objects by writing an IDL (Interface

Definition Language) file. Oracle Media Net provides an IDL compiler for creating

C programming language files from your IDL files.

Oracle Media Net also provides an IFR (interface repository) that you can load with

object interface definitions. You can then write applications that use DII (dynamic

invocation interface) to query the IFR at run time and construct requests for objects

defined there.

Oracle Media Net

Scalability and Load Balancing

If demand for a server (such as an OVS service) increases, you can start additional

instances of the server to better handle it. Oracle Media Net can distribute requests

for a server across available instances to balance the load among them. If one

instance fails, Oracle Media Net can redistribute new requests across the remaining

instances.

Logging Error and Warning Messages

Oracle Media Net logs error and warning messages for the OVS system. For

example, if the OVS rejects a client connection request, messages in the log explain

why.

Logging is configurable:

■ You can configure a common event logging daemon to write messages for all

components of the OVS system to a common logfile.

■ You can run multiple event logging daemons. For example, you can configure

multiple daemons in a hierarchy so that several daemons each log messages for
a group of components and forward only the severe messages to a single
daemon. This daemon then writes to a logfile or console and alerts an
application service of only the most severe messages. You can then program the
application service to notify the administrator.

System Architecture 2-17

Oracle Video Client (OVC)

Oracle Video Client (OVC)

Oracle Video Client (OVC) software is useful for developing multimedia
applications that receive and display video and for accessing and receiving video
from the OVS at run time.

Application Development

OVC software enables you as the application developer to develop interactive,
video-based multimedia applications. OVC software includes these tools to help
you build applications:

■ Oracle Video Java Library

The Oracle Video Java Library enables you as the application developer to

embed video in a Java application that runs with the appletviewer or from the

command line.

■ Oracle Video ActiveX Control

The Oracle Video ActiveX Control is an ActiveX control that enables you to

embed video in compliant 32-bit multimedia applications, such as Microsoft

Visual Basic, Developer 2000/Oracle Forms, and Oracle Power Objects, that

start, stop, and seek locations within video streams from the OVS.

■ Oracle Video Web Plug-in

The Oracle Video Web Plug-in enables World Wide Web pages to embed video

streams from the OVS. The Oracle Video Web Plug-in is compatible with

Internet browsers that support Netscape plug-ins, such as Netscape Navigator

and Microsoft Internet Explorer. You can also use Java and JavaScript and with

Netscape’s LiveConnect interface to customize the control of the Oracle Video

Web Plug-in, for example, to add clickable buttons or icons to play, pause, and

seek video and pop up lists of available content.

2-18 Introducing Oracle Video Server

Run-Time Capability

At run time, OVC software runs on the client device and:

■ connects to the OVS

■ accepts input from the client application

■ requests video and audio from the OVS

■ receives video and audio in MPEG or OSF format and displays it

Specialized third-party software or hardware decoders decompress video data.

OVC software applications can receive and display video content using Microsoft’s

ActiveMovie framework and ActiveMovie-compliant decoders. The decoder

requires smooth, reliable video delivery and the network may sometimes deliver

packets late or out of order. OVC software ensures proper decoder operation by re-

ordering packets properly and buffering a small amount of data so the decoder is

consistently provided with ordered video data.

OVC software can dynamically connect to and disconnect from different instances

of the OVS without stopping and restarting.

Oracle Video Client (OVC)

System Architecture 2-19

OVS System Hardware and Network Architecture

OVS System Hardware and Network Architecture

This section presents the OVS system hardware. The OVS system uses the
hardware components shown in Figure 2–8.

Figure 2–8 OVS system hardware

PC or NC or set-top box that:

• accepts user input

• requests data from the OVS

• receives data and displays it for the user

Runs the OVS
to store and deliver
multimedia data

Client Device

Application

Oracle Video Client

Audio/Video

Decoders

Carries video and control messages between servers and
clients and can be:

• symmetric — upstream and downstream traffic use

• asymmetric — upstream and downstream traffic use

Web

Browser

Oracle

Media

Net

Network

the same physical network connection

different connections

Video Server Computer

Oracle Media Net

Oracle Video Server

Database Server
Computer

Oracle Server

Optionally runs the Oracle Server
for the database for logical content

and scheduling

2-20 Introducing Oracle Video Server

In a production environment, to ensure real-time delivery with no glitches, the

video server computer must be dedicated to running the OVS:

■ If you use logical content or scheduling, the Oracle Server for the database

must run on a separate database server computer.

■ If you develop server-side applications to run with your OVS, such as an

application responsible for authenticating and billing clients, they must run on
separate application server computers.

How the OVS System Communicates

This section presents these concepts related to communication in the OVS:

■ Circuits

■ Sessions

and discusses these processes:

■ How Client Devices Connect to the OVS

How the OVS System Communicates

Circuits

Sessions

■ How the OVS Delivers Video

A circuit is a path of communication between the client and the OVS. A circuit can

be one of these types:

■ upstream—carrying control messages (such as requests for video) from the

client to the OVS

■ downstream—carrying control messages (such as acknowledgments of

requests) and video from the OVS to the client

■ bidirectional—carrying control messages in both directions between the client

and the OVS

A client connecting to the OVS establishes a session. A session consists of:

■ an identifier for the client

■ one or more circuits through which control messages and video are transported

between the client and the OVS

■ resources, or state information for the client and its connection to the OVS

System Architecture 2-21

How the OVS System Communicates

The types of circuits within a session depend on the symmetry of the network the
OVS system uses. This section discusses:

■ Sessions in Symmetric Networks

■ Sessions in Asymmetric Networks

Sessions in Symmetric Networks

In symmetric networks each client session contains two circuits:

■ a bidirectional circuit that carries control messages between the client and the

OVS

■ a downstream circuit that delivers video from the OVS to the client

Figure 2–9 shows a client and its session with the OVS.

Figure 2–9 Communication in a symmetric network

Client Device

Application

Oracle Video Client

Audio/Video

Decoders

Web

Browser

Oracle

Media

Net

Network

All IP (Internet Protocol) networks are symmetric by definition.

Control Messages

Video

Video Server
Computer

Oracle Media Net

Oracle Video Server

2-22 Introducing Oracle Video Server

How the OVS System Communicates

Sessions in Asymmetric Networks

In asymmetric networks each client session contains:

■ an upstream circuit carrying control messages from the client to the OVS, and

■ a downstream circuit carrying control messages and delivers video from the

OVS to the client

Figure 2–10 shows a client and its session with the OVS.

Figure 2–10 Communication in an asymmetric network

Client Device

Application

Oracle Video Client

Audio/Video

Decoders

Web

Browser

Oracle

Media

Net

Upstream

Network

Downstream

Network

How Client Devices Connect to the OVS

A client connects to the OVS by following these steps:

1. OVC obtains a Media Net address from the OVS. This address allows the client

to communicate with components of the OVS through Oracle Media Net.

Control Messages

Video

VideoServer Computer

Oracle Media Net

Oracle Video Server

2. OVC establishes a session with the OVS that includes one or more circuits so

that the OVS can send and receive control messages to and from the client and
deliver video to the client.

Some broadband networks contain a service provider called a level 1 gateway

(L1GW) that acts as a proxy for the client by contacting the OVS and establishing a

session and circuits for the client.

System Architecture 2-23

How the OVS System Communicates

How the OVS Delivers Video

Figure 2–11 illustrates steps the OVS system follows to deliver video. This example

uses a symmetric network. Steps 7 through 12 make up a video round trip, or a
request from an application met by video delivery from the OVS.

Figure 2–11 An OVS system round trip

Client Device

6

12

Application

Web Browser

Oracle Video Client

Audio/Video

Decoders

1 User requests content
titles from client application

2 Oracle Media Net
carries request to OVS

3 OVS queries
database
for titles

4 Oracle Server
reads titles and

returns them to OVS

1
7

Oracle

Media

Net

25

Network

8 Oracle Media Net
carries request to
OVS

9 OVS queries
database for MDS files
associated with requested title

10 Oracle Server maps
title to MDS files

8

Video Server Computer

Oracle Media Net

Oracle Video Server

11

3

MDS

9

Database Server
Computer

5 Oracle Media Net
returns list of titles
to client application

6 Client application
displays titles for user

7 User requests
a title to play

2-24 Introducing Oracle Video Server

11 OVS:

• finds and opens MDS files

• associates video stream with

client’s downstream circuit

• streams encoded video
to client in real time

12 Client application:

• receives video

• decodes video

• displays video

Oracle Server

4

10

Database

Components of Oracle Video Server and Oracle Media Net

Components of Oracle Video Server and Oracle Media Net

The individual components of Oracle Video Server and Oracle Media Net work
closely with each other and with client applications. This section describes Oracle
Video Server and Oracle Media Net components shown in Figure 2–12.

Figure 2–12 also shows typical paths of communication for connecting to Oracle

Video Server and delivering video. Many messages that do not appear in the figure
pass between Oracle Video Server components and client devices via the ORB
daemon.

Each Oracle Video Server and Oracle Media Net process can accommodate
multiple clients, depending on the type of video server computer. For large
numbers of clients, the Oracle Video Server can run multiple instances of most
processes. Figure 2–12 shows only one instance of each process.

Figure 2–12 Components of Oracle Video Server and Oracle Media Net

Oracle Media Net

Oracle Video Server

CORBA

event service

CORBA

naming service

From

Clients

From

L1GW

To

Clients

Control

Video

MDS

remote file

service

MDS
FTP

service

MDS

directory

service

session and

circuit

service

video
pump

MDS

stream
service

ORB

daemon

real-time feed

service

content
service

transfer service

HSM

instances

address
server

event logging

daemon

NVOD

exporter

service

HSM

service

tape drive

broadcast

data

service

scheduler

service

name
server

event log

reader

Oracle Server

database

System Architecture 2-25

Components of Oracle Video Server and Oracle Media Net

Oracle Media Net ORB Daemon

The Oracle Media Net ORB (object request broker) daemon receives requests for
services from clients and routes them to the appropriate servers. For servers with
multiple instances, the ORB daemon balances the load of requests across the
instances and redistributes requests if an instance fails. These clients and servers
can be located on either the same computer or on different computers on a
network. The ORB daemon manages the following details and keeps them
transparent from clients and servers:

■ where client and server applications are located

■ how to transport and convert data between different types of computers

When a service is started, it registers its name and Media Net address with the ORB
daemon.

Oracle Media Net Name Server

The Oracle Media Net name server maps the names of ORB daemons to their
Media Net addresses. When an ORB daemon is started, it registers its name and
Media Net address with the name server.

An OVS system can run only one name server.
Do not confuse the name server with the Oracle Media Net CORBA naming service

discussed later in this section.

Oracle Media Net Address Server

Each component has an Media Net address that uniquely identifies it in the Oracle
Media Net network. The Oracle Media Net address server maps Media Net
addresses to corresponding physical addresses:

■ When a client device connects to the OVS, it provides its physical address and

is assigned a Media Net address by the address server.

■ When a server process is started, it registers its physical address with the

address server and is assigned a Media Net address.

■ Before a client can send a message to the server, it contacts the address server to

find the server’s physical address.

An OVS system can run only one address server.

2-26 Introducing Oracle Video Server

Components of Oracle Video Server and Oracle Media Net

The address server is responsible for invalidating addresses of failed processes.
When a process on the OVS system is idle, it periodically sends a heartbeat, a
message announcing its existence, to the address server. If the address server does
not detect a message from a process for a period of minutes, the address server
assumes a failure and invalidates the process’ address.

Oracle Media Net Event Logging Daemon

The Oracle Media Net event logging daemon writes error and warning messages
for the OVS system components to a logfile. The event logging daemon is
configurable:

■ You can configure the event logging daemon to log either all messages or only

those above a severity threshold.

■ You can use message logging filters to configure the event logging daemon to

log specific information about components.

■ You can configure the maximum size of a log file. After filling a log file, the

event logging daemon automatically begins writing to a new one.

Oracle Media Net Event Log Reader

The Oracle Media Net event log reader interprets and displays information written
to the logfile by the Oracle Media Net event logging daemon to make this
information easier to interpret.

Oracle Media Net CORBA Event Service

An event is data that indicates a change in an object. The Oracle Media Net CORBA
event service provides for the notification of clients when an event occurs. When
something of note occurs in an object, an event may be generated to notify clients
of the occurrence so each client can react. For example, when a client device
requests a video content file, the stream service prepares to play the file and notifies
the CORBA event service. A billing application may note this event to bill the client
application for playing the video.

An OVS system can run only one CORBA event service.

System Architecture 2-27

Components of Oracle Video Server and Oracle Media Net

Oracle Media Net CORBA Naming Service

The Oracle Media Net CORBA naming service enables clients to locate and obtain
object references from name strings. The CORBA naming service associates objects
with names and organizes these object names hierarchically in contexts similar to
the way a file system organizes file names in directories. For example, the Oracle
Media Net CORBA event service uses the CORBA naming service to name event
channels.

An OVS system can run only one CORBA naming service.
Do not confuse the CORBA naming service with the Oracle Media Net name server

discussed earlier in this section.

Session and Circuit Service

The session and circuit service allocates sessions and circuits for clients connecting
to the OVS. An OVS can run only one session and circuit service.

The session and circuit service may consult a third-party component called a
channel manager when allocating a circuit for a client. The channel manager has
specific network implementation information that is not available to the session
and circuit service. After allocating a circuit, the session and circuit service sends it
to the channel manager for approval. The channel manager can approve the circuit
or suggest another one.

When a client ends its session, the session and circuit service deallocates all the
session’s circuits and resources.

Oracle MDS Directory Service

The MDS (Media Data Store) directory server controls access to MDS files and
manages their layout on disk.

Processes that read or write MDS files must first gain access through the MDS
directory server. For example, when a video pump is instructed to play a video file,
it opens the file by sending a message to the MDS directory server that returns a
small structure describing the layout of the file on disk. With this structure, the
video pump accesses the file’s contents directly. This direct access prevents the
MDS directory server from becoming an I/O bottleneck.

2-28 Introducing Oracle Video Server

Components of Oracle Video Server and Oracle Media Net

Oracle MDS Remote File Service

The MDS remote file server:

■ provides access to MDS files for remote processes such as MDS utilities and

applications on remote computers

■ delivers BLOBs to clients on request

Oracle MDS FTP Service

The MDS FTP (file transfer protocol) service performs binary file transfers between
the MDS and FTP clients on remote computers. A single MDS FTP service runs on
the video server computer. The MDS FTP service listens for requests from remote
clients on a dedicated port.

The MDS FTP service only accesses files in the MDS, not on the video server
computer host file system. Host files can be accessed through the video server
computer host FTP service which listens for requests on a different dedicated port.

HSM Service

The HSM (hierarchical storage management) server controls access to files in
tertiary storage and manages their layout in a way similar to how the MDS
directory server manages files in the MDS.

HSM T ransfer Service

The HSM transfer service copies files between tertiary storage and MDS volumes
on disk when requested by an HSM utility.

Stream Service

The stream service handles requests from clients for video and audio content.
When the stream service receives a request, it obtains necessary information to
meet the request:

■ The stream service contacts the content service to resolve a request for a logical

content title to one or more tag files.

■ The stream service reads the tag file(s) associated with the request. Each tag file

describes which portion of a requested file must be delivered to meet the
request.

The stream service tells the video pump which parts of the physical content files to
play.

System Architecture 2-29

Components of Oracle Video Server and Oracle Media Net

Video Pump

The video pump reads video files from the MDS and delivers them to the network
in real time. When a client requests video, the video pump receives a message from
the stream service, reads the appropriate portion of the file from the MDS, and
sends video data over the network through the appropriate downstream channel to
the client.

Real-Time Feed Service

The real-time feed service accepts this input from a one-step encoder:

■ encoded content

■ associated tag information

To support one-step encoding, the real-time feed service writes the encoded content
to one or more content files and the tag information to an associated tag file. The
stream service and video pump can then play the content.

To support a continuous real-time feed, the real-time feed service maintains a pool
of physical content files and writes the encoded content to one file after another.
The real-time feed service deletes the oldest files as they become out of date and
writes new ones. The real-time feed service also maintains a single tag file for all
physical content files in the pool.

Content Service

The content service maintains information that maps logical content to physical
content in the database.

When creating a tag file for a physical content file, the tagging utility calls the
content service to generate logical content based on the content file. As the
administrator, you can also call the content service to generate logical content titles
each representing a series of parts of physical content files.

A client application can query the content available in the OVS system through the
content service. On request of the client application, the content service reads from
the database and returns a list of logical content to the client.

The content service also receives requests from the stream service to resolve logical
content to physical tag files.

2-30 Introducing Oracle Video Server

Broadcast Data Service

The broadcast data service manages broadcast scheduling information in the
database. The broadcast data service reads broadcast scheduling information, such
as schedules, from the database and writes it to memory where it can be read by
the scheduler service and by exporter services, such as the NVOD exporter service.
The broadcast data service also provides interfaces enabling you to schedule
broadcast events.

Scheduler Service

The scheduler service keeps track of the current time and a list of scheduled events
and notifies the appropriate exporter service, such as the NVOD exporter service,
when a broadcast event is scheduled to occur.

NVOD Exporter Service

The NVOD exporter service plays a scheduled logical content title on a scheduled
channel when notified by the schedule service. You can use this service to handle
any scheduled video, including NVOD, pay-per-view, or regular TV broadcasting.

Networking in the OVS System

Networking in the OVS System

The OVS system can be deployed on many different network types. Depending on
the environment, these networks can be either:

■ a PSTN (public switched telephone network) using IP (Internet Protocol) and

TCP (Transmission Control Protocol) or UDP (User Datagram Protocol)
network used in Internet environments

■ a LAN (local-area network), typically used in intranet environments

■ Broadband Network, used in the broadband environment

System Architecture 2-31

Networking in the OVS System

PSTN

In Internet environments, clients communicate with both an ISP (Internet Service
Provider) and the OVS. These communications use separate network connections:

■ Clients communicate with an ISP through a PSTN using IP. A PSTN may

consist of:

■ POTS (plain old telephone service)

■ ISDN (Integrated Services Digital Network)

■ ADSL (Asymmetric Digital Subscriber Loop)

■ Clients communicate with the OVS through a TCP or UDP network connection.

LAN

In intranet environments, the OVS system uses switched Ethernet on a LAN to
ensure consistent error-free video delivery and to reduce network congestion.
Unlike shared Ethernet in which every computer reads every data packet, switched
Ethernet uses a hardware hub that provides a dedicated link to each client. The
dedicated link allows the hub to physically map each client IP address to the
communication channel between the hub and the client. The switched Ethernet hub
examines the IP address of each packet as it moves through the hub and routes it
directly to its destination segment ensuring that data in the communication channel
between the hub and a client is destined for that client. Each client views only its
data and does not spend time examining packets addressed to others on the same
communication channel.

The switched Ethernet hub also has high capacity input allowing for the
multiplexing of video streams from the server to many clients from a single line. A
high capacity interface, such as FDDI (Fiber Distributed Data Interface) or CDDI
(Copper Distributed Data Interface), handles many video streams from the video
server computer at once, with a dedicated segment for each client, ensuring
optimum performance for both the dedicated segments and the entire network.

The rest of this section explains why an OVS system using a LAN requires
switched Ethernet and discusses these topics:

■ Ethernet

■ Demands of Video on LANs

2-32 Introducing Oracle Video Server

Networking in the OVS System

Ethernet

This section discusses these Ethernet terms:

■ Packets

■ Bus/Broadcast Topology

■ Best-Effort Delivery

Packets A packet is the basic unit of information that travels between computers
on a LAN. All data transmitted over a LAN, whether a small message or a large
video file, is divided into packets. Each packet contains a header and data. The
header contains:

■ information about data in the packet

■ sequencing information

■ the address of the receiving computer

■ a checksum of the packet data

For Oracle Media Net packets, the receiving computer gathers the packets it
receives and reassembles them based on the packet sequence in the header. The
receiver can identify missing packets based on information in the headers of the
received packets and corrupted packets based on the checksum information in their
headers. If a packet is missing or has been corrupted, the receiver requests that the
sending computer resend the packet and waits for its return before reassembling
the data for the user.

Bus/Broadcast T opology The most common type of Ethernet topology is a bus
topology, in which all computers on the network are connected to the same

communication channel. When one computer wants to send data over the network
to another, it checks the data channel for data packet traffic and broadcasts the first
packet when the channel is clear. If the data takes up multiple packets, the sender
waits again until the channel is clear to transmit the next packet. This continues
until all the packets have been sent. As a packet is broadcast on the channel, it is
seen by all computers on the network. The packet is only useful to the computer to
which it is addressed, denoted by the address in the packet header. This type of
network is called shared Ethernet because all computers on the network share the
same data channel.

System Architecture 2-33

Networking in the OVS System

Best-Effort Delivery Ethernet uses best-effort delivery, which means that when
data is sent over the network, every effort is made to deliver the data. However, if
the receiving computer is turned off or if there is a network problem, the data is
lost. Ethernet does not notify the sending computer when a message is received or
dropped.

Demands of Video on LANs

A shared Ethernet network is sufficient for non-real-time applications such as
databases or word processors, in which delays of a fraction of a second in receiving
data are not critical and are often not noticed by users.

However, applications receiving video are time-sensitive and depend on
isochronous, or time-based, delivery. Data packets must arrive on time to be useful,
or the video suffers a brief interruption and the user notices a glitch in the video.
Glitch-free video is not easy to deliver on a shared Ethernet network because:

■ All data traffic from one computer to another is read by all computers on the

network.

■ Video cannot be delivered as a continuous string of packets, but as multiple

individual packets that compete equally with other applications for network
resources.

■ The large number of packets needed to deliver video consumes network

resources. For example, 20 video streams at an encoding rate of 1.5 Mbps
(Megabits per second) require a total network rate of 30 Mbps, which is much
greater than standard 10baseT Ethernet network rates.

■ A shared Ethernet network card can drop packets due to transmission timeouts

in heavy network traffic.

Once a video stream starts, it must continue and finish uninterrupted by other data
transfers or by glitches. To ensure uninterrupted video:

■ Video cannot be interrupted by other network traffic such as large file transfers.

■ The network must be capable of sustained data transfer rates that support the

maximum video encoded rate multiplied by the number of concurrent video
streams.

Switched Ethernet meets both of these requirements.

2-34 Introducing Oracle Video Server

Broadband Network

In a broadband environment, one broadband network delivers video from the OVS
to clients and another carries messages in both directions between clients and the
OVS.

The network may use various protocols, such as ATM (Asynchronous Transfer
Mode) or X.25 (for control messages only), depending on the network protocol.

Networking in the OVS System

System Architecture 2-35

Networking in the OVS System

2-36 Introducing Oracle Video Server

Index

A

accessing files, 2-7

remote computers, 2-13
address server, 2-26
addresses, 2-26

failed processes, 2-27
advertisements, 2-14
allocating sessions, 2-28
applications, 2-16, 2-17

non-real-time, 2-34

remote, 2-16
archives, 2-12
asymmetric connections, 2-23
audio output

multiplexing, 2-2

playback rate control, 2-4, 2-14
automatic playback, 2-15

B

best-effort delivery (Ethernet), 2-34
bidirectional circuits, 2-21
billing applications, 2-27
binary file transfers, 2-13, 2-29
broadband environments, 1-11
broadband networks, 2-23, 2-35
buffers, 2-19
bus topology (Ethernet), 2-33

C

C programming language, 2-17
channel manager, 2-28

circuits

asymmetric connections, 2-23
broadband networks, 2-23
defined, 2-21

symmetric connections, 2-22
client (defined), 2-16
client applications, 2-30
client connections, 2-23

multiple, 2-25
client requests, 2-26, 2-29
codecs, 2-2 to 2-4

defined, 2-2

supported types, 2-2
command line utilities, 2-12
communications, 2-21 to 2-23
compressing video data, 2-2, 2-19
compression format, 2-2

See also codecs
configuring log files, 2-27
connections, 2-19

broadband networks, 2-23, 2-35

client devices, 2-23

Ethernet cards, 2-33

Internet environments, 2-32

intranet environments, 2-32

multi-platform, 2-16

multiple clients, 2-25

symmetric vs. asymmetric, 2-22, 2-23
container formats, 2-2 to ??

defined, 2-2

supported types, 2-3
content, 2-2 to 2-5

creating, 2-2

defined, 2-2

Index-1

requesting, 2-29
storing, 2-6

content files, 2-4

See also tag files
mappings, 2-30

playing, 2-29
content service, 2-30
continuous real-time feeds, 2-5, 2-30
CORBA

event service, 2-27

naming service, 2-28

terms defined, 2-17
crashes, 2-8, 2-10

D

data

reconstructing, 2-10, 2-11

storing, 2-12
databases, 2-34
decoders, 2-19
defragmenter utility, 2-10, 2-12
deleting files from volumes, 2-10
deliverable files, 2-2
delivering files, 2-13 to 2-14
delivering video data, 2-24
digital video

challenges, 1-8

client

customizing, 1-8

defined, 1-7
defined, 1-1 to 1-14
server

defined, 1-4
traditional media vs., 1-2 to 1-4
usage, 1-4 to 1-14

directory server, 2-28
directory structure information, 2-10
disk errors, 2-6
disk failures, 2-8, 2-10
disk space allocation, 2-10
disk volumes, 2-7, 2-10

RAID (Redundant Arrays of Inexpensive Disks)

protection, 2-8
reclaiming space, 2-10

spare disks, 2-11

downstream circuits, 2-21

E

encoding, 2-2, 2-4, 2-30
encoding software, 2-2
enterprise environments, 1-13
environments

broadband, 1-11

enterprise, 1-13
error logs, 2-17, 2-27
errors, 2-6
Ethernet cards, 2-32 to 2-34

best-effort delivery, 2-34

bus topology, 2-33
Ethernet terms, 2-33
event (defined), 2-27
event log reader, 2-27
event logging daemon, 2-27
event service, 2-27

F

failed processes, 2-27
file transfer protocol server, 2-29
file transfers, 2-13, 2-29
files, 2-2, 2-6

accessing, 2-7

remote computers, 2-13
deleting from volumes, 2-10
delivering, 2-13 to 2-14
rebuilding, 2-10, 2-11
storing, 2-3, 2-10

FTP server, 2-29
full raw keyframe codecs, 2-4

G

gateways, 2-23
generating tag files, 2-30

H

hardware, 2-20

Index-2

heartbeat, 2-27
Hierarchical Storage Management

See HSM
host files, 2-29
hot-swapping disks, 2-11
HSM

utilities, 2-12
HSM (Hierarchical Storage Management), 2-16

I

reclaiming space, 2-10

spare disks, 2-11
messages, 2-16
MPEG

container formats, 2-3

storage compression ratio, 2-3
multimedia applications, 2-18

See also applications
multi-platform connections, 2-16
multiplexing, 2-2

IDL compiler, 2-17
IDL files, 2-17
IFR (interface repository), 2-17
interface (defined), 2-17
Interface Definition Language (IDL) files, 2-17
interface repository, 2-17
Internet environments

network connections, 2-32

intranet environments

network connections, 2-32

isochronous delivery, 2-34

L

L1GW (Level 1 Gateway), 2-23
LAN systems, 2-32
Level 1 Gateway (L1GW), 2-23
load balancing, 2-17, 2-26
logical content, 2-5
logs, 2-17, 2-27
loops, 2-14

M

MDS ( Media Data Store)

striping, 2-8

supported file types, 2-6
MDS directory server, 2-28
MDS files, 2-28, 2-29
MDS FTP server, 2-29
MDS remote server, 2-29
MDS utilities, 2-12
MDS volumes, 2-7, 2-10

RAID protection, 2-8

N

name server, 2-26
naming service, 2-28
Near Video-on-Demand (NVOD), 1-3
networking infrastructure, 2-16
networks

asymmetric connections, 2-23
broadband, 2-23, 2-35
Ethernet cards, 2-32 to 2-34
Internet connections, 2-32
intranet connections, 2-32
supported systems, 2-15

discussion, 2-31

symmetric connections, 2-22
noncontiguous RAID stripes, 2-10
non-real-time applications, 2-34
non-redundant data, 2-9
notifications, 2-27

O

object (defined), 2-17
object references, 2-28
object request broker, 2-26
one-step encoding, 2-4, 2-30
Oracle Media Net, 2-16 to 2-17

address server, 2-26

CORBA

event service, 2-27

naming service, 2-28
event log reader, 2-27
event logging daemon, 2-27
name server, 2-26

Index-3

ORB daemon, 2-26

mappings, 2-26

packet transfers, 2-33, 2-34
Oracle Video Client, 2-18 to 2-19
Oracle Video Custom Control, 2-18
Oracle Video Marker, 2-1
Oracle Video Server

communications protocol, 2-21 to 2-23

deliverable files, 2-2

file transfers, 2-13

networks supported, 2-15

discussion, 2-31

system hardware, 2-20
Oracle Video Server Manager, 2-15
Oracle Video Web Plug-in, 2-18
ORB daemon See under Oracle Media Net

P

packet (defined), 2-33
packet reordering, 2-19
packet transfers, 2-33, 2-34
parity information, 2-10

storage, 2-9
parity stripes, 2-10
Pause function, 2-14
playback

automatic, 2-15

continuously repeating, 2-14

functions, 2-14

nonsupported formats, 2-4

rate control mechanism, 2-4, 2-14
preface

conventions table sample, xii
processes failing, 2-27
PSTN systems, 2-32
public service announcements, 2-14
public switched telephone network (PSTN), 2-32

Q

queries, 2-17, 2-30

R

RAID (Redundant Arrays of Inexpensive Disks)

protection, 2-8 to 2-10
sets, 2-8, 2-10
size, 2-8
stripes, 2-9, 2-10

labeling, 2-10
noncontiguous, 2-10

reads, 2-30

MDS files, 2-28
real-time feed server, 2-30
real-time feeds, 2-14
real-time processing, 2-4, 2-5
rebuild utility, 2-10, 2-12
rebuilding files, 2-10, 2-11
reliability, 2-8
remote access, 2-13
remote applications, 2-16
remote server, 2-29
reordering packets, 2-19
requests, 2-26, 2-29
resources (defined), 2-21
Resume function, 2-14
round trip, 1-15 to 1-20, 2-24

S

searches, 2-5
Seek forward/backward function, 2-14
server

defined, 2-16, 2-17

demand, 2-17, 2-26
sessions, 2-21 to 2-23

allocating, 2-28

defined, 2-21
shared Ethernet networks, 2-32, 2-33, 2-34
space allocation, 2-10
spare disk (defined), 2-11
state information, 2-21
storage, 2-6 to 2-11

content, 2-6

data, 2-12

disk failures, 2-8

hierarchical management, 2-12

Index-4

non-redundant data, 2-9
parity information, 2-9
space allocation, 2-10

video files, 2-3, 2-10
storage compression ratio (MPEG), 2-3
stream service, 2-29
streams, 2-13, 2-34
stripe (defined), 2-7
striping, 2-7 to 2-8

defined, 1-4, 2-7

RAID protection, 2-9
switched Ethernet networks, 2-32, 2-34
symmetric connections, 2-22
system failures, 2-8, 2-10

T

tag files, 2-4

generating, 2-30

logical content, 2-5
tagging utility, 2-4, 2-30
tape archival utility, 2-12
tape archives, 2-12
tertiary storage, 2-12
third-party encoding software, 2-2
time-based delivery, 2-34

delivering, 2-13 to 2-14
reading, 2-30

storing, 2-3, 2-10
video pump, 2-30
video streams, 2-13, 2-34
viewing

continuous, 2-14, 2-30
volumes, 2-7, 2-10

RAID protection, 2-8

reclaiming space, 2-10

spare disks, 2-11

W

warning messages, 2-17, 2-27
Web plug-ins, 2-18
wildcards, 2-12
word processors, 2-34
writes, 2-7, 2-10

MDS files, 2-28

U

upstream circuits, 2-21
utilities, 2-12

See also specific

V

variance, 2-6
video data

compressing, 2-2, 2-19
delivering, 2-24
Ethernet cards, 2-34
multiplexing, 2-2
nonsupported playback formats, 2-4
playback rate control, 2-4, 2-14
searches, 2-5

video files, 2-4

Index-5

Index-6