Orban OPTICODEC-PC 1010 Technical Manual

Technical Manual

OPTICODEC-PC

1010

AAC/HE AAC/aacPlus® Audio Streaming Encoder

for Windows

PRELIMINARY: Version 1.0 Software

®

2000 / XP / 2003 Server

IMPORTANT NOTE: Refer to the unit’s rear panel for your Model #.

Model Number: Description:

1010 LE OPTICODEC-PC LE, AAC/HE AAC/aacPlus encoder for

a single stream of 8-32 kbps, for use with any qual­ity, Windows-compliant sound card.

1010 PE OPTICODEC-PC PE, AAC/HE AAC/aacPlus encoder for

multiple streams of 8-320 kbps, for use only with the
Orban Optimod-PC sound card/audio processor.

MANUAL:

Part Number: Description:

96127.100.01 OPTICODEC-PC Operating Manual

This symbol, wherever it appears, alerts you to important

operating and maintenance instructions in the accompa-

nying literature. Read the manual.

PLEASE READ BEFORE PROCEEDING!

Manual

Please review the Manual, especially the installation section, before installing the software.

Trial Period Precautions

If your unit has been provided on a trial basis:

You should observe the following precautions to avoid reconditioning charges in case you later wish to return the unit to
your dealer:

Note the packing technique and save all packing materials. It is not wise to ship in other than the factory carton. (Re­placements cost $35.00).

Packing

When you pack the software for shipping:

Wrap the unit in its original plastic bag to avoid abrading the paint.

If you are returning the unit permanently (for credit), be sure to enclose:

The Manual(s)
The Registration/Warranty Card
The installation CD

Your dealer may charge you for any missing items.

Trouble

If you have problems with installation or operation:

(1) Check everything you have done so far against the instructions in the Manual.

(2) Check the other sections of the Manual (consult the Table of Contents and Index) to see if there might be some sug-

gestions regarding your problem.

(3) After reading the section on Factory Assistance, you may call Orban Customer Service for advice during normal Cali-

fornia business hours. The number is [phone].

Technical Manual

OPTICODEC-PC

1010

AAC/HE AAC/aacPlus® Audio Streaming Encoder

for Windows

®

2000 / XP / 2003 Server

PRELIMINARY: Version 1.0 Software

OPTICODEC-PC is manufactured under license from Coding Technologies Inc.
and Dolby Laboratories Licesning Corporation.

Opticodec, Optimod, and Orban are registered trademarks.
All trademarks are property of their respective companies.

This manual is part number 96127.100.01

© Copyright 2004 CRL Systems Inc.

Phone: [phone]; Fax: [phone]; E-Mail: [e-mail]; Web: www.orban.com

1525 ALVARADO STREET, SAN LEANDRO, CA 94577 USA

Forward

Several years ago, one of the most successful radio stations in North America was
CKLW in Windsor/Detroit. Innovative, technically superb audio complemented “The
Big 8”’s excellent execution of their Top 40 program format to give the station a big
signature sound that I have never forgotten. Its striving for perfection has been an
inspiration and has influenced the goals, designs, and sounds of many Orban Opti­mod products to this day.

If it weren’t for CKLW’s innovative audio texture and the chances that it took to ex­pose the world to many great artists, these discoveries would never have become
part of the radio and music history that they now are. Just as many of these great
artists have moved on from creating hit music to fusing their old styles with newer
forms such as smooth jazz, Orban is evolving by giving the world new viable broad­cast technology that build on its legacy.

I dedicate this technical manual to CKLW and those who made it the reality it once
was, and to Leo, my faithful dog, who was beside me, night after night and day af­ter day in the long process of preparing this document.

As the world moves on embracing innovative ways to deliver audio to an audience,
“ladies and gentlemen, the beat goes on…” – Bill Drake, radio programmer

– Greg J. Ogonowski

Table of Contents

Forward ............................................................................................................................................ 0-7

......................................................................................SECTION 1 INTRODUCTION

.......................................................................................................................................................1-1

ABOUT THIS MANUAL ................................................................................................................1-1

OVERVIEW..................................................................................................................................1-1

Streaming Infrastructure Block Diagrams ............................................................................1-2

Figure 1-1: Typical streaming infrastructure where program material is sourced from a playout

system application with live assist.................................................................................................... 1-2

Figure 1-2: Typical streaming infrastructure where program material is sourced from a radio station

on-air studio...................................................................................................................................... 1-3

Figure 1-3: Typical multiple streaming encoder/server infrastructure where program material is

sourced from a player application..................................................................................................... 1-3

SPECIFICATIONS AND SYSTEM REQUIREMENTS ..........................................................................1-4

PE Version .............................................................................................................................1-4

LE Version.............................................................................................................................1-5

APPLICATIONS............................................................................................................................ 1-6

Preprocessing........................................................................................................................1-6

Remote Access & Control:............................................................................................................... 1-7

Mixing Facilities:.............................................................................................................................. 1-8

Encoding................................................................................................................................1-8

About Perceptual Coders.................................................................................................................. 1-9

Psychoacoustic Models..................................................................................................................... 1-9

Coding Efficiency........................................................................................................................... 1-10

Encoding Stereo.............................................................................................................................. 1-10

Opticodec-PC Codecs..................................................................................................................... 1-10

Table 1-1: aacPlus Audio Bandwidth vs. Bitrate, Sample rate, and Channel Mode....................... 1-11

Table 1-2: AAC Audio Bandwidth vs. Bitrate, Sample rate, and Channel Mode........................... 1-12

Trading-Off Audio Bandwidth against Bitrate, Sample rate, and Channel Mode..........................1-13

Cascading Codecs........................................................................................................................... 1-14

Networking ..........................................................................................................................1-15

Network Bandwidth Considerations............................................................................................... 1-15

Bandwidth Requirements ............................................................................................................... 1-16

Table 1-3: Bandwidth Requirements for Typical Network Streams............................................... 1-16

STREAMING ARCHITECTURE.....................................................................................................1-17

Live Streaming.....................................................................................................................1-17

File Streaming .....................................................................................................................1-17

Overview of Streaming Architecture ...................................................................................1-18

Network Transports.............................................................................................................1-18

Figure 1-4: Server Transports and Protocols.................................................................................. 1-18

Streaming Server Advantages..............................................................................................1-19

Web Server Advantages.......................................................................................................1-19

RTSP/RTP — Streaming Servers.........................................................................................1-20

Figure 1-5: QTSS/DSS Server/Client Transports........................................................................... 1-21

HTTP/ICY — Streaming Servers.........................................................................................1-22

Figure 1-6: SHOUTcast DNAS Server/Client Transports.............................................................. 1-22

Figure 1-7: Icecast2 Server/Client Transports................................................................................ 1-23

HTTP — Web Servers..........................................................................................................1-23

Figure 1-8: Web Server/Client Transports......................................................................................1-24

Unicast................................................................................................................................ 1-24

Figure 1-9: Unicast .........................................................................................................................1-24

Multicast ............................................................................................................................. 1-25

Figure 1-10: Multicast.....................................................................................................................1-25

Relay Servers ...................................................................................................................... 1-25

Figure 1-11: Relay Server...............................................................................................................1-26

Table 1-4: Summary of Server Capabilities and Compatibilities....................................................1-26

Playing a Stream ................................................................................................................. 1-27

............................................SECTION 2 INSTALLATION — STREAMING ENCODER

......................................................................................................................................................2-1

INSTALLING OPTICODEC-PC...................................................................................................... 2-1

Opticodec-PC PE.................................................................................................................. 2-1

Opticodec-PC LE.................................................................................................................. 2-1

Software Installation............................................................................................................. 2-1

Software Authentication........................................................................................................ 2-3

CONFIGURING OPTICODEC-PC................................................................................................... 2-3

Configuration — Graphical User Interface (GUI)...............................................................2-4

Figure 2-1: The Opticodec-PC GUI..................................................................................................2-4

Sound Device....................................................................................................................................2-4

Encoder Parameters ..........................................................................................................................2-4

Table 2-1: Recommended Maximum Target Bitrates.......................................................................2-5

Stream Description............................................................................................................................ 2-5

Destination Server.............................................................................................................................2-6

Audio Levels.......................................................................................................................... 2-8

Configuration — Command Line Interface (CLI)................................................................. 2-8

Querying Audio Devices...................................................................................................................2-8

Command-Line Syntax – Unicast.....................................................................................................2-8

Command-Line Syntax – Multicast..................................................................................................2-9

Arguments.........................................................................................................................................2-9

Creating Batch Files........................................................................................................................2-10

Audio Levels...................................................................................................................................2-10

.........................................SECTION 3 CONFIGURATION — STREAMING ENCODER

......................................................................................................................................................3-1

UNICAST — RTSP/RTP DARWIN STREAMING SERVER ............................................................. 3-1

Encoder/Server — Same Computer ...................................................................................... 3-1

Encoder Destination Server Parameters:...........................................................................................3-2

Encoder/Server — Different Computer................................................................................. 3-2

Encoder Destination Server Parameters:...........................................................................................3-3

Server Connection................................................................................................................. 3-3

Firewall Considerations ....................................................................................................... 3-3

Table 3-1: Firewall or router configuration for RTSP/RTP Darwin Streaming Server.....................3-3

MULTICAST – RTSP/RTP DARWIN STREAMING SERVER........................................................... 3-4

Encoder Destination Server Parameters:............................................................................. 3-4

Multicast Relay ..................................................................................................................... 3-5

Multicast Addresses .............................................................................................................. 3-5

Firewall Considerations ....................................................................................................... 3-5

UNICAST — HTTP/ICY SHOUTCAST ...................................................................................... 3-6

Encoder Destination Server Parameters:............................................................................. 3-6

Firewall Considerations ....................................................................................................... 3-7

Table 3-2: Firewall or router configuration for HTTP/ICY SHOUTcast ......................................... 3-7

UNICAST — HTTP/ICY ICECAST2.............................................................................................3-7

Encoder Destination Server Parameters:..............................................................................3-8

Firewall Considerations........................................................................................................3-8

Table 3-3: Firewall or router configuration for HTTP/ICY Icecast2................................................ 3-8

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

SECTION 4 STREAMING SERVERS

.......................................................................................................................................................4-1

INTRODUCTION...........................................................................................................................4-1

DARWIN STREAMING SERVER (DSS)..........................................................................................4-1

Supported Protocols..............................................................................................................4-1

DSS Installation — Windows.................................................................................................4-2

Operating System Requirements ...................................................................................................... 4-3

Software Requirements..................................................................................................................... 4-3

Optional Useful Network Utilities.................................................................................................... 4-3

Installation.............................................................................................................................4-3

Security: Access and Authentication .....................................................................................4-5

Opticodec-PC Encoder and DSS on the Same Computer .....................................................4-5

Opticodec-PC Encoder Destination Server Parameters:................................................................... 4-5

Opticodec-PC Encoder and DSS on Different Computers....................................................4-6

Opticodec-PC Encoder Destination Server Parameters – Any User................................................. 4-6

Opticodec-PC Encoder Destination Server Parameters – Limit User............................................... 4-6

Authenticated Client Player Access.......................................................................................4-6

Access Control.......................................................................................................................4-7

Allow Write Access.......................................................................................................................... 4-7

qtaccess file to allow any encoder access to DSS:...................................................................... 4-7

qtaccess file to limit encoder access to DSS:.............................................................................. 4-7

Allow Authenticated Client Player Access....................................................................................... 4-7

qtaccess file for authenticated client player access:.................................................................... 4-7

Access File Reference ...................................................................................................................... 4-7

To Add a User:.................................................................................................................................4-9

To Change a User Password:............................................................................................................ 4-9

Group File Reference (Optional)...................................................................................................... 4-9

To Add a Group:............................................................................................................................. 4-10

To Delete a User from a User or Group File: ................................................................................. 4-10

Remote Administration........................................................................................................4-10

Other Configuration Options...............................................................................................4-10

Firewall Considerations......................................................................................................4-11

Table 4-1: Firewall configuration for various protocols and servers.............................................. 4-11

SHOUTCAST™ DNAS (DISTRIBUTED NETWORK AUDIO SERVER).........................................4-12

Supported Protocol..............................................................................................................4-12

Installation – Microsoft Windows........................................................................................4-12

Operating System Requirements .................................................................................................... 4-13

Software Requirements................................................................................................................... 4-13

Optional Useful Network Utilities.................................................................................................. 4-13

Installation...........................................................................................................................4-13

Configuration — Single Stream...........................................................................................4-13

Configuration — Multiple Streams......................................................................................4-14

Server User Interface...........................................................................................................4-16

Figure 4-1: SHOUTcast DNAS graphical user interface................................................................ 4-16

Remote Administration........................................................................................................4-16

Firewall Considerations......................................................................................................4-16

Table 4-2: Firewall considerations for SHOUTcast DNAS............................................................4-17

ICECAST2................................................................................................................................. 4-17

Supported Protocol.............................................................................................................4-17

Installation — Microsoft Windows...................................................................................... 4-18

Operating System Requirements.....................................................................................................4-18

Software Requirements...................................................................................................................4-18

Optional Useful Network Utilities..................................................................................................4-18

Installation..........................................................................................................................4-18

Configuration...................................................................................................................... 4-19

Server User Interface.......................................................................................................... 4-20

Figure 4-2: Icecast Server Status Tab .............................................................................................4-20

Figure 4-3: Icecast Source Level Stats Tab.....................................................................................4-21

Streaming Files...................................................................................................................4-21

Remote Administration........................................................................................................ 4-21

Firewall Considerations ..................................................................................................... 4-22

Table 4-3: Firewall considerations; Icecast2...................................................................................4-22

MULTIPLE SERVERS................................................................................................................. 4-22

....................................................................................SECTION 5 CLIENT PLAYERS

......................................................................................................................................................5-1

COMPARISONS ........................................................................................................................... 5-1

Software Client Player Platforms ......................................................................................... 5-1

Table 5-1: Software Client Player Platforms ....................................................................................5-1

Software Client Player AAC/HE AAC/aacPlus Codecs........................................................ 5-1

Table 5-2: Software Client Player AAC/HE AAC/aacPlus Codecs..................................................5-1

Software Client Player File Formats....................................................................................5-2

Table 5-3: Software Client Player File Formats................................................................................5-2

Software Client Player Streaming Protocols........................................................................5-2

Table 5-4: Software Client Player Streaming Protocols....................................................................5-2

REAL NETWORKS REALPLAYER 10............................................................................................ 5-3

Figure 5-1: RealPlayer 10 GUI.........................................................................................................5-3

Direct URL Entry and Play................................................................................................... 5-3

Metafile/Playlist Files...........................................................................................................5-4

Additional RealPlayer Parameters and Values..................................................................................5-5

Table 5-5: Additional RealPlayer Parameters and Values................................................................5-6

Options.................................................................................................................................. 5-6

Live/File Stream Linking in a Web Page .............................................................................. 5-8

Embedded Players ................................................................................................................5-9

APPLE COMPUTER QUICKTIME 6.............................................................................................5-10

Figure 5-2: Apple QuickTime 6 GUI (shown playing a live Opticodec-PC stream)......................5-10

Direct URL Entry and Play................................................................................................. 5-10

Metafile/Playlist Files.........................................................................................................5-11

Table 5-6: Additional QuickTime Player Parameters and Values ..................................................5-12

Options................................................................................................................................ 5-13

Figure 5-3: QuickTime Default Streaming Transport Settings.......................................................5-13

Figure 5-4: QuickTime UDP Settings.............................................................................................5-14

Figure 5-5: QuickTime HTTP Settings...........................................................................................5-14

Live/File Stream Linking in a Web Page ............................................................................ 5-14

Embedded Players .............................................................................................................. 5-15

NULLSOFT WINAMP 5.05.........................................................................................................5-16

Figure 5-6: Winamp 5.05 GUI (shown playing a live Opticodec-PC stream).................................5-16

Direct URL Entry and Play................................................................................................. 5-16

Metafile/Playlist Files..........................................................................................................5-17

Options ................................................................................................................................5-20

Figure 5-7: Winamp 5.05 Preferences – General Preferences / File Types.................................... 5-20

Live/File Stream Linking in a Web Page.............................................................................5-20

MULTIPLE PLAYERS ON A SINGLE COMPUTER..........................................................................5-21

..............................................................................SECTION 6 SERVICE PROVIDERS

.......................................................................................................................................................6-1

Content Delivery – Hosting Services.....................................................................................6-1

Content Encoding – Audio Production..................................................................................6-1

Authoring – Multimedia Web Design....................................................................................6-1

Live Encoding – Streaming & Netcasting .............................................................................6-2

.......................................................................................... SECTION 7 REFERENCES

.......................................................................................................................................................7-1

INFORMATION.............................................................................................................................7-1

BOOKS AND PUBLICATIONS........................................................................................................7-1

INTERNET LINKS.........................................................................................................................7-2

...............................................................................................SECTION 8 GLOSSARY

.......................................................................................................................................................8-1

DEFINITIONS...............................................................................................................................8-1

OPTICODEC-PC INTRODUCTION

1-1

Section 1

Introduction

About this Manual

The Adobe pdf form of this manual contains numerous hyperlinks and bookmarks. A
reference to a numbered step or a page number (except in the Index) is a live hyper­link; click it to go immediately to that reference.

If the bookmarks are not visible, click the “Bookmarks” tab on the left
side of the Acrobat Reader window.

This manual has a table of contents. To search for a specific word or phrase, you can
use the Adobe Acrobat Reader’s text search function.

Overview

Opticodec-PC is the first standards-based MPEG-4 AAC/aacPlus™, AAC/HE AAC, ISMA
compliant and SHOUTcast/Icecast compatible encoding software for high quality
streaming audio. Opticodec-PC offers the most important feature that the basic net­caster is looking for in an encoding product — entertainment-quality sound at eco­nomical bitrates.

The software lets streaming providers supply content encoded with the Coding
Technologies
available audio quality at the lowest possible bitrate. Streams encoded with Optico­dec-PC can be experienced through RealPlayer
ous Ethernet players, and 3G wireless devices. Streams can automatically list them­selves on www.opticodec.net

Opticodec-PC offers a choice of a standards-based RTSP/RTP streaming protocol for
use with streaming servers (such as the free enterprise-class, scaleable Darwin
Streaming Server from Apple) or the HTTP/ICY streaming protocol (for use with
SHOUTcast or Icecast Servers). Both server types are non-proprietary and available
for most computer platforms, and some servers are open-source.

Professional radio broadcasters would never consider going on the air without audio
signal processing. They consider it a vital component of the program content, con­tent being what attracts listeners. This carefully crafted content is what holds listen­ers and keeps them coming back. Broadcast ratings services have proven this true for
over 30 years. Over that period, Orban’s patented Optimod technology has helped
radio and television broadcasters everywhere shape their sound to grab and hold
their listening audiences.

®

AAC/aacPlus codec, widely acknowledged as offering the highest

®

10, QuickTime 6, Winamp 5.05, vari-

, a directory service for Opticodec-PC streams.

1-2

INTRODUCTION ORBAN MODEL 1010

Professional-grade netcasting requires audio processing similar to FM broadcast (al­though there are some important differences in the peak limiting because of the
different characteristics of the pre-emphasized FM channel and the perceptually
coded netcasting channel). Your listeners deserve to get the best quality and consis­tency you can provide. Good audio processing is one important thing that separates
the amateur from the professional.

The Orban Optimod-PC 1100, a

professional PCI sound card designed for streaming
media, provides “genuine radio”™ audio processing for Internet broadcasters. With
three on-board DSP's providing mixing, equalization, AGC, multi-band compression,
and look-ahead limiting, Optimod-PC 1100, especially when combined with aacPlus
encoding technology, delivers a polished and produced stream that has the same
loudness, consistency, and punch as satellite and major-market FM radio. In addition
to audio processing, Optimod-PC does internal and external audio mixing, leaving
the CPU power available for encoding with Opticodec-PC. Together, Optimod-PC
and Opticodec-PC provide a unique and tightly tuned system that offers the best
audio quality streams possible with today’s technology.

Opticodec-PC is available in two versions, LE, and PE. Opticodec-PC LE, Light Edition,
is compatible with all quality sound cards and encodes a single stream at bitrates
between 8 and 32 kbps. Opticodec-PC PE, Professional Edition, is offered solely in a
premium package coupled with an Optimod-PC and can encode multiple simultane­ous streams at bitrates from 8 to 320 kbps; all streams carry the same Optimod-PC
processed audio content. While the companion Optimod-PC will ordinary be used to
process the stream for consistency and punch, it also comes with presets that allow it
to do simple protection limiting.

Streaming Infrastructure Block Diagrams

AUDIO
INPUTS

Microphone

Pre-A mp

Mixer

Player

Application

PLAYER / ENCODER COMPUTER

ANALOG 1

DIGITAL 1

DIGITAL 2

WAV OUT

WAV IN

OPTIMOD-PC

PCI Sound Card

WAV OUT

Metadata

WAV IN

OPTICODEC-PC

To Server From Encoder

Streaming Audio

Encoder

TCP/UDP/IP

Figure 1-1: Typical streaming infrastructure where program material is sourced from a play-

out system application with live assist

Internet

Network

To Internet

TCP/UDP/IP

SERVER COMPUTER

QTSS/DSS

Streaming Server

OPTICODEC-PC INTRODUCTION

1-3

From
Broadcast
Program Line

AUDIO
INPUTS

ANALOG 1

DIGITAL 1

DIGITAL 2

Metadata

To Server From Encoder

Internet

Network

To Internet

OPTIMOD-PC

PCI Sound Card

WAV OUT

ENCODER COMPUTER

WAV IN

OPTICODEC-PC

Streaming Audio

Encoder

TCP/UDP/IP

TCP/UDP/IP

SERVER COMPUTER

Figure 1-2: Typical streaming infrastructure where program material is sourced from a

radio station on-air studio

OID

UA

STUPNI

ANALOG 1

DIGITAL 1

DIGITAL 2

OPTICODEC-PC

Streaming Audio

Encoder

tenretnI

tenrehtE

redocnE lanretxE morFrevreS lanretxE oT

QTSS/DSS

Streaming Server

tenretnI oT

QTSS/DSS

Streaming Server

WAV IN WAV IN

Playout System

WAV OUT

WAV IN

OPTIMOD-PC

PCI Sound Card

WAV OUT

WAV IN

Figure 1-3: Typical multiple streaming encoder/server infrastructure where program ma-

terial is sourced from a player application

Streaming Audio

Streaming Audio

Encoder

Encoder

TCP/UDP/IP TCP/UDP/IP

TCP/UDP/IP

OPTICODEC-PC

OPTICODEC-PC

0008:1.0.0.721 tsohlacol

SHOUTcast

Streaming Server

0108:1.0.0.721 tsohlacol

TCP/UDP/IP TCP/UDP/IP TCP/UDP/IP

Icecast2

Streaming Server

RETUPMOC REVRES / REDOCNE / REYALP

1-4

INTRODUCTION ORBAN MODEL 1010

Opticodec-PC offers the best available tradeoff between audio quality and bitrate.
Compared to MP3, Opticodec-PC provides a better than 60% improvement in audio
quality versus bitrate, reducing network streaming bandwidth requirements and
costs accordingly. At 32 kbps, Opticodec-PC streams offer close to FM quality, with­out the phasey, watery character of other codecs operating at this bitrate. Many lis­teners prefer the audio quality of 48 kbps streams to FM.

There is a vast Internet and 3G wireless audience waiting for the entertainment­quality audio that Orban Opticodec-PC and Optimod-PC can provide.

Specifications and System Requirements

PE Version

COMPUTER

Minimum System Requirements:

Windows 2000: Intel® Pentium II 400MHz, RAM = 64MB; 128MB recommended.
Windows XP: Intel® Pentium II 400MHz, RAM = 128MB; 256MB recommended.
Windows 2003 Server Intel® Pentium III 500 MHz
RAM = 256MB; 512 MB recommended

This specification denotes the minimum CPU power necessary to control one
OPTIMOD-PC card with external audio sources and one instance of the OPTICODEC­PC encoder. Additional cards, audio player and/or encoder software will require addi­tional CPU power.

Processor and Chipset: This software has been tested and qualified with Intel CPUs and

chipsets.

Sound Device: An Optimod-PC 1100 audio processor / sound card must be installed in the

host computer in order to run the Opticodec-PC PE application.

Interface: Graphical User and Command-Line, batchable

ENCODER

Codec Technology: MPEG-2/MPEG-4 AAC/HE AAC /aacPlus v2 — Coding Technologies®

Sample Rates: 24 kHz, 32 kHz, 44.1 kHz, 48 kHz

Bitrates: 8, 10, 12, 16, 20, 24, 32, 40, 48, 56, 64, 80, 96, 128, 160, 192, 224, 256, 320 kbps

Number of Channels: 1-Mono / 2-Stereo

Coding Options: General; Voice

Number of Encoder Instances per Computer: Limited only by available CPU power.

STREAMING

Transport Protocols: RTSP/RTP, HTTP/ICY SHOUTcast, HTTP/ICY Icecast

RTP Payload Format: ISMA (

Method: Unicast RTP/TCP (External RTSP Server)

audio/mpeg4-generic) / 3GPP/3GPP2 (audio/MP4A-LATM)

OPTICODEC-PC INTRODUCTION

1-5

Transmission: Automatic Unicast – Announce – Session Description
Protocol (.sdp) file per stream generated and transferred to server

Multicast RTP/UDP (Internal RTSP Server)

TTL: 255 default

Unicast HTTP/TCP

Packet Size: 1450 bytes plus IP Header Bytes = Total < 1500 byte MTU

Connection Fallback: Automatic Reconnection upon Connection Failure

Stream Information: Stream Name and Description; all server supported metadata

Metadata Input: Text File, Serial, Ethernet, Nullsoft Winamp

Server Requirements: Darwin Streaming Server 5.0 and later, QuickTime Streaming

Server 5.0 and later, Nullsoft SHOUTcast DNAS 1.9.4 and later, Icecast2 2.0.2 and later

Server Platform: Available for Microsoft Windows 2000 Professional/Server, Windows 2003

Server, Windows XP Professional, Apple Mac OS X 10.2.8 and later Server and Proxy,
Red Hat Linux 9, FreeBSD, Sun Solaris 9

LE Version

COMPUTER

Minimum System Requirements:

Windows 2000: Intel® Pentium II 400MHz, RAM = 64MB; 128MB recommended.
Windows XP: Intel® Pentium II 400MHz, RAM = 128MB; 256MB recommended.
Windows 2003 Server Intel® Pentium III 500 MHz
RAM = 256MB; 512 MB recommended

This specification denotes the minimum CPU power necessary to control one
OPTIMOD-PC card with external audio sources and one instance of the OPTICODEC­PC encoder. Additional cards, audio player and/or encoder software will require addi­tional CPU power.

Processor and Chipset: This software has been tested and qualified with Intel CPUs and

chipsets.

Sound Device: Opticodec-PC LE will operate with any Windows-qualified sound card capa-

ble of the required sample rate and bit depth.

Interface: Graphical User and Command-Line, batchable

ENCODER

Codec Technology: MPEG-2/MPEG-4 AAC/HE AAC /aacPlus v2 — Coding Technologies®

Sample Rates: 24 kHz, 32 kHz, 44.1 kHz, 48 kHz

Bitrates: 8, 10, 12, 16, 20, 24, 32 kbps

Number of Channels: 1-Mono / 2-Stereo

Coding Options: General; Voice

Number of Encoder Instances per Computer: 1.

1-6

INTRODUCTION ORBAN MODEL 1010

STREAMING

Transport Protocols: RTSP/RTP, HTTP/ICY SHOUTcast, HTTP/ICY Icecast2
RTP Payload Format: ISMA (audio/mpeg4-generic)

Stream Information: Name and Description

Method: Unicast RTP/TCP (External RTSP Server)

Transmission: Automatic Unicast – Announce – Session Description
Protocol (.sdp) file per stream generated and transferred to server

Multicast RTP/UDP (Internal RTSP Server)

TTL: 255 default

Unicast HTTP/TCP

Packet Size: 1450 bytes plus IP Header Bytes = Total < 1500 byte MTU

Connection Fallback: Automatic Reconnection upon Connection Failure

Stream Information: Stream Name and Description, all server supported metadata

Metadata Input: Text File, Serial, Ethernet, Nullsoft Winamp

Server Requirements: Free Darwin Streaming Server 5.0 and later, QuickTime Streaming

Server 5.0 and later, Nullsoft SHOUTcast DNAS 1.9.4 and later, Icecast2 2.0.2 and later

Server Platform: Available for Microsoft Windows 2000 Professional/Server, Windows 2003

Server, Windows XP Professional, Apple Mac OS X 10.2.8 and later Server and Proxy,
Red Hat Linux 9, FreeBSD, Sun Solaris 9

These specifications are subject to design improvements and changes
without notice.

Opticodec-PC TE, Test Edition is available upon request for testing en­coder/server connectivity. With limited functionality, it allows testing
network connectivity and authentication to verify server configuration.

Applications

Putting your audio content on the Internet or your LAN can be divided into three
main steps: preprocessing the audio signal, encoding it, and streaming it to the net­work.

High quality streams begin with the cleanest possible audio source material. For best
results, all material should be sourced in digital form to prevent any potential distor­tion from occurring in the analog-to-digital conversion process. CDs should be digi­tally extracted (ripped) to a PCM audio format if the digital storage system allows
this, or to a 384 kbps or higher MPEG-1 Layer 2 format. Avoid Layer 3, as well as
other codecs. More information on this topic can be obtained from the Orban publi­cation, “Maintaining Audio Quality in the Broadcast Facility,” available as a free
download from http://www.orban.com.

Preprocessing

For optimum sound, loudness, and peak control, you should digitally preprocess the
Internet audio signal to condition it prior to encoding. The appropriate preprocess­ing has much in common with the preprocessing required for DAB, HD Radio™, CD
mastering, or digital satellite.

OPTICODEC-PC INTRODUCTION

Preprocessing is necessary for several reasons. Automatic gain control and equaliza­tion achieve a consistent sound, while accurate peak control maximizes loudness.

Preprocessing each program element before it is stored on a playout system is not as
effective as preprocessing the mixed audio on the program line immediately before
it is streamed. The latter technique maximizes the smoothness of transition between
program elements and makes voice from, announcers, or presenters merge smoothly
into the program flow, even if the announcer is talking over music.

Peak clipping sounds terrible in digital systems because these systems do not rely on
pre-emphasis/de-emphasis to reduce audible distortion. Instead of peak clipping, the
best sounding processors use some form of look-ahead limiting. The carefully peak
limited signal is then digitally connected to Opticodec-PC to preserve the audio sig­nal waveform integrity.

Orban Optimod-PC (recommended for Opticodec PC LE and required for Opticodec­PC PE to operate) is a PCI sound card with on-board digital signal processing that is
suitable for both live streaming and on-demand programming. Its three on-board
Motorola DSP56362 DSP chips provide a loud, consistent sound to the consumer by
performing automatic gain control, equalization, multiband gain control, and peak­level control. Optimod-PC’s sound card emulation allows it to talk through the oper­ating system via the Windows’ WAVE mechanism to Opticodec-PC, running on the
same computer that houses Optimod-PC.

While there are several types of audio processors available other than Optimod-PC,
conventional AM, FM, or TV audio processors that employ pre-emphasis/de-emphasis
and/or clipping peak limiters are most inappropriate for use with perceptual audio
coders such as Opticodec-PC. The pre-emphasis/de-emphasis limiting in these devices
unnecessarily limits high frequency headroom. Further, their clipping limiters create
high frequency components— distortion—that the perceptual audio coders would
otherwise not encode. None of these devices has the full set of audio and control
features found in Optimod-PC.

Without Optimod-PC processing, audio can sound dull, thin, or inconsistent in any
combination. Optimod-PC’s multiband processing automatically levels and re­equalizes its input to the “major-market” standards expected by the mass audience.
Broadcasters have known for decades that this polished, produced sound attracts
and holds listeners.

You can expect a very large increase in loudness from Optimod-PC processing by
comparison to unprocessed audio (except for audio from recently mastered CDs,
which are often overprocessed in mastering). Broadcasters generally believe that
loudness relative to other stations attracts an audience that perceives the station as
being more powerful than its competition. We expect that the same subliminal psy­chology will hold in netcasting too.

Remote Access & Control:

Optimod-PC has the unique ability to be remotely accessed and controlled over any
TCP/IP network. After the appropriate security and administration setup, Optimod­PCs I/O mixer, processing parameters, and presets can be controlled from anywhere,
including from other applications.

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INTRODUCTION ORBAN MODEL 1010

Mixing Facilities:

In addition to sound card and audio processing functionality, Optimod-PC is also a
capable mixer, having one stereo analog input, two AES3 / SPDIF digital inputs
(which can accept any sample rate from 32 to 96 kHz), and one WAVE input (to ac­cept Windows sound sources), all of which can be mixed. Thanks to onboard sample
rate converters, the two digital inputs can accept and mix asynchronous sources,
which may have different sample rates. In practice, the four inputs might be used
for a local feed, a network feed, a voice channel, and a wave player, making Opti­mod-PC the heart of a “desktop netcasting studio.” In many cases, this versatility
allows you to avoid use of an external mixing desk, thereby keeping the audio path
100% digital. The wave player could be any one of a number of broadcast-oriented
automated playout systems.

Using Optimod-PC’s separate “processed” and “unprocessed” mixers, any of the in­puts in any combination can be processed or passed directly to the input of Optico­dec-PC without processing—you can always choose how much processing (if any) to
apply to the audio. These features allow local program insertion, such as those re­quired in order to address the broadcast rights issues of many commercials, pro­grams, and events.

Because it uses Microsoft DirectSound Drivers, Optimod-PC is able to play multiple
audio streams from multiple audio sources, eliminating the need for multiple or
multi-channel sound devices for professional playout systems used in automation
mode. Given the CPUs available today, MPEG1 Layer 2, and/or Layer 3 decoding can
occur at the operating system level, eliminating the requirement for expensive
hardware-based MPEG decoder sound devices.

Encoding

Opticodec-PC receives the output of Optimod-PC, which looks like a sound card to
the operating system. Opticodec-PC then reduces the bitrate of the processed signal
by applying it to an AAC or aacPlus perceptual coder and packetizing the resulting
data for an Ethernet network. When the encoder connects to the streaming server,
the encoder generates the Session Description Protocol file and transfers it auto­matically to the streaming server.

The most basic use of Opticodec-PC is to create a single stream at a single bitrate.
However, the output of a given Optimod-PC card can feed several Opticodec-PC en­coders running at different bitrates to service different audience bandwidths; all of
these streams will carry the same audio program.

If you need more than one audio program stream, use multiple Optimod-PC cards
(some of which can be housed in one or more PCI expansion chassis). If you need
multiple streams at different bitrates, configure each Optimod-PC card to feed its
own array of Opticodec-PC PE encoders.

Each installation of Opticodec-PC PE is keyed to one Optimod-PC card, so
running more than one audio program stream requires one Opticodec-PC
PE installation per audio program stream even if all of these installations
are on one computer. However, a single Opticodec-PC installation can
create multiple streams at different bitrates if all of these streams contain
the same audio program.

OPTICODEC-PC INTRODUCTION

About Perceptual Coders

CD-quality audio (16-bit words at 44.1 kHz sample rate) requires 705,600 bits per
second per channel, which is far too high for economical streaming. Perceptual cod­ing reduces the number of bits per second necessary to transmit a high-quality audio
signal.

Perceptual coders exploit models of how humans perceive sound. In particular, per­ceptual coders exploit the phenomenon of psychoacoustic masking. This means that
louder sounds will “drown out” (or “mask”) weaker sounds occurring at the same
time, particularly if the frequency of the louder sound is close to the weaker sound’s
frequency. Loud sounds not only mask weak sounds occurring simultaneously in
time (spectral masking), but can also drown out weak sounds occurring a few milli­seconds before the loud sound starts or a few milliseconds after it stops (temporal
masking).

The basic principle of perceptual coding is to divide the audio into frequency bands
and then to code each frequency band with the minimum number of bits that will
yield no audible change in that band. Reducing the number of bits used to encode a
given frequency band raises the quantization noise floor in that band. If the noise
floor is raised too far, it can become audible and cause artifacts.

A second major source of artifacts in codecs is pre- and post-echo caused by ringing
of the narrow bandpass filters used to divide the signal into frequency bands. This
ringing worsens as the number of bands increases, so some codecs may adaptively
switch the number of bands in use, depending on whether the sound has significant
transient content. This ringing manifests itself as a smearing of sharp transient
sounds in music, such as those produced by claves and wood blocks.

Psychoacoustic Models

Perceptual coders exploit complex models of the human auditory system to estimate
whether a given amount of added noise can be heard. They then adjust the number
of bits used to code each frequency band such that the added noise is undetectable
by the ear if the total “bit budget” is sufficiently high. Because the psychoacoustic
model in a perceptual coder is an approximation that never exactly matches the be­havior of the ear, it is desirable to leave some safety factor when choosing the num­ber of bits to use for each frequency band. This safety factor is often called the
“mask-to-noise ratio,” measured in dB. For example, a mask-to-noise ratio of 12 dB
in a given band would mean that the quantization noise in that band could be
raised by 12 dB before it would be heard. (That is, there is a safety margin of two
bits in that band’s coding.) For the most efficient coding, the mask-to-noise ratio
should be the same in all bands, ensuring that the sound elements equitably share
the available bits in the transmission channel.

Increasing the number of bits per second in the transmission always improves the
mask-to-noise ratio. It is important to allocate extra bits to the transmission if the
audio will be processed after it has been decoded at the output of the perceptual
coder (for example, by a second “cascaded” perceptual coder, or by a multiband au­dio processor such as Optimod-PC). Done correctly, this increased bitrate will raise
the mask-to-noise ratio far enough to prevent downstream processing from causing
the noise to become unmasked.

Because it occurs in narrow frequency bands, unmasked noise does not
sound like familiar white noise at all. Instead, it most often sounds like

1-9

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INTRODUCTION ORBAN MODEL 1010

distortion, or like warbling, comb filtering, or gurgling—an “underwa­ter” sound.

Coding Efficiency

Different sounds will vary greatly in the efficiency with which a perceptual coding
system can encode them. Therefore, for a constant transmission bitrate, the mask­to-noise ratio will constantly change. Pure sounds having an extended harmonic
structure (such as a pitch pipe) are particularly difficult to encode because each har­monic must be encoded, the harmonics occupy many different frequency bands, and
the overall spectrum has many “holes” that are not well-masked, so that added
noise can be easily heard. The output of a multiband audio processor that uses clip­ping is another sound that is difficult to encode, because the clipper creates added
distortion spectrum that does not mask quantization noise well, yet may cause the
encoder to waste bits when trying to encode the distortion.

Sophisticated encoders use a short “bit reservoir” to save up unused bits so they can
be applied to difficult-to-encode sounds. However, the length of the bit reservoir
will directly affect the coding delay, so dynamic allocation of bits occurs only over
rather short time windows (in the order of tens of milliseconds). Another feature of
sophisticated encoders is “redundancy reduction,” which encodes frequently ap­pearing data with shorter digital words and infrequently appearing data with
longer words.

Encoding Stereo

Usually, there is some correlation between the left and right channels of a stereo
signal. At lower bitrates, one way to achieve higher quality is to exploit this correla­tion when coding stereo information:

Depending on program content, the encoder dynamically switches between discrete
left/right coding and sum-and-difference coding. The difference signal often re­quires fewer bits than the sum signal to encode with high audible quality, thereby
saving bits in the overall coding of the stereo signal.

There is no benefit to joint stereo coding when the two channels contain
independent information because there is no correlation between the
channels.

Opticodec-PC Codecs

Opticodec-PC offers two coding algorithms from the several standardized by
ISO/MPEG (Moving Pictures Experts Group): the AAC and aacPlus® v2 algorithms.

AAC is intended for very high quality coding with compression up to 12:1. The AAC
codec is about 30% more efficient than MPEG1 Layer 3 and about twice as efficient
as MPEG1 Layer 2. The AAC codec can achieve “transparency” (that is, listeners can­not audibly distinguish the codec’s output from its input in a statistically significant
way) at a stereo bitrate of 128 kb/sec, while the Layer 2 codec requires about 256
kb/sec for the same quality. The Layer 3 codec cannot achieve transparency at any
bitrate, although its performance at 192 kbps and higher is still very good.

AAC stands for Advanced Audio Coding. Intended to replace Layer 3, AAC was de­veloped by the MPEG group that includes Dolby, Fraunhofer (FhG), AT&T, Sony, and
Nokia—companies that have also been involved in the development of audio codecs
such as MP3 and AC3 (also known as Dolby Digital™).

OPTICODEC-PC INTRODUCTION

1-11

AAC does not stand for Apple Audio Codec, although Apple was one of
the first to implement this technology with the introduction of Apple
iTunes and QuickTime 6.

The Coding Technologies “Spectral Band Replication” (SBR) process can be added to
almost any codec. This system transmits only lower frequencies (for example, below
8 kHz) via the codec. The decoder at the receiver creates higher frequencies from
the lower frequencies by a process similar to that used by “psychoacoustic exciters.”

Channel
Mode

1ch-Mono 8 24 8.3
1ch-Mono 10 24, 32 10.9, 11.0
1ch-Mono 12 24, 32, 44.1 11.4, 11.0, 10.7
1ch-Mono 16 32, 44.1, 48 12.3, 11.7, 12.0
1ch-Mono 20 32, 44.1, 48 14.5, 14.8, 15.4
1ch-Mono 24 32, 44.1, 48 15.3, 14.8, 15.4
1ch-Mono 28 32, 44.1, 48 16.0, 16.2, 16.9
1ch-Mono 32 32, 44.1, 48 16.0, 16.2, 16.9
1ch-Mono 40 32, 44.1, 48 16.0, 17.6, 18.4
1ch-Mono 48 32, 44.1, 48 16.0, 20.3, 20.3
1ch-Mono 56 32, 44.1, 48 16.0, 20.3, 20.3
1ch-Mono 64 32, 44.1, 48 16.0, 20.3, 20.3
2ch-Stereo 24 32, 44.1, 48 13.8, 12.7, 13.1
2ch-Stereo 28 32, 44.1, 48 15.3, 14.8, 15.4
2ch-Stereo 32 32, 44.1, 48 15.3, 14.8, 15.4

Bitrate
[kbps]

Sample rate
[kHz]

Audio Bandwidth
[kHz]

2ch-Stereo 40 32, 44.1, 48 16.0, 16.2, 16.9
2ch-Stereo 48 32, 44.1, 48 16.0, 16.2, 16.9
2ch-Stereo 56 32, 44.1, 48 16.0, 17.6, 18.4
2ch-Stereo 64 32, 44.1, 48 16.0, 20.3, 22.1
2ch-Stereo 80 32, 44.1, 48 16.0, 20.3, 22.1
2ch-Stereo 96 32, 44.1, 48 16.0, 20.3, 22.1
2ch-Stereo 112 32, 44.1, 48 16.0, 20.3, 22.1
2ch-Stereo 128 32, 44.1, 48 16.0, 20.3, 22.1

Table 1-1: aacPlus Audio Bandwidth vs. Bitrate, Sample rate, and Channel Mode

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INTRODUCTION ORBAN MODEL 1010

Channel
Mode

1ch-Mono 16 24 5.2
1ch-Mono 20 24 7.2
1ch-Mono 24 24, 32 7.2, 7.2
1ch-Mono 28 24, 32 10.0, 10.0
1ch-Mono 32 24, 32, 44.1, 48 10.0, 10.0, 10.0, 10.0
1ch-Mono 40 24, 32, 44.1, 48 12.0, 12.4, 12.4, 12.4
1ch-Mono 48 24, 32, 44.1, 48 12.0, 13.5, 13.5, 13.5
1ch-Mono 56 24, 32, 44.1, 48 12.0, 15.5, 15.5, 15.5
1ch-Mono 64 32, 44.1, 48 15.5, 15.5, 15.5
1ch-Mono 80 32, 44.1, 48 16.0, 17.6, 17.6
1ch-Mono 96 32, 44.1, 48 16.0, 22.1, 24.0
1ch-Mono 112 32, 44.1, 48 16.0, 22.1, 24.0
1ch-Mono 128 32, 44.1, 48 16.0, 22.1, 24.0
1ch-Mono 160 32, 44.1, 48 16.0, 22.1, 24.0
2ch-Stereo 24 24 6.6

Bitrate
[kbps]

Sample rate
[kHz]

Audio Bandwidth
[kHz]

2ch-Stereo 28 24 6.6
2ch-Stereo 32 24 6.6
2ch-Stereo 40 24, 32 8.5, 8.5
2ch-Stereo 48 24, 32 8.5, 8.5, 8.5
2ch-Stereo 56 24, 32, 44.1, 48 12.0, 12.5, 12.5, 12.5
2ch-Stereo 64 32, 44.1, 48 12.5, 12.5, 12.5
2ch-Stereo 80 32, 44.1, 48 13.5, 13.5, 13.5
2ch-Stereo 96 32, 44.1, 48 15.5, 15.5, 15.5
2ch-Stereo 112 32, 44.1, 48 16.0, 16.0, 16.0
2ch-Stereo 128 32, 44.1, 48 16.0, 16.0, 16.0
2ch-Stereo 160 32, 44.1, 48 16.0, 17.6, 17.6
2ch-Stereo 192 32, 44.1, 48 16.0, 22.1, 24.0
2ch-Stereo 224 32, 44.1, 48 16.0, 22.1, 24.0
2ch-Stereo 256 32, 44.1, 48 16.0, 22.1, 24.0
2ch-Stereo 320 32, 44.1, 48 16.0, 22.1, 24.0

Table 1-2: AAC Audio Bandwidth vs. Bitrate, Sample rate, and Channel Mode

OPTICODEC-PC INTRODUCTION

A low-bandwidth signal in the compressed bit stream provides “hints” to modulate
these created high frequencies so that they will match the original high frequencies
as closely as possible. Adding SBR to the basic AAC codec creates aacPlus, which of­fers the best subjective quality currently available at bitrates below 128 kbps. At bi­trates below 128 kbps, full subjective transparency cannot be achieved at the cur­rent state of the art, yet the sound can still be very satisfying. (In the phraseology of
the ITU 1 to 5 subjective quality scale, this means that audible differences introduced
by the codec are judged by expert listeners to be “detectable, but not annoying.”)

Coding Technologies’ aacPlus v2, the latest in MPEG-4 Audio and previously known
as "Enhanced aacPlus," is aacPlus coupled with the new MPEG Parametric Stereo
technique created by Coding Technologies and Philips. Where SBR enables audio
codecs to deliver the same quality at half the bitrate, Parametric Stereo enhances
the codec efficiency a second time for low-bitrate stereo signals. Both SBR and Pa­rametric Stereo are backward- and forward-compatible methods to enhance the ef­ficiency of any audio codec. As a result, aacPlus v2 delivers streaming and
downloadable 5.1 multichannel audio at 128 Kbps, near CD-quality stereo at 32
Kbps, excellent quality stereo at 24 Kbps, and great quality for mixed content down
to 16 Kbps and below.

MPEG standardized Coding Technologies’ aacPlus as MPEG-4 HE AAC (MPEG ISO/IEC
14496-3:2001/AMD-1: Bandwidth Extension). With the addition of MPEG Parametric
Stereo (MPEG ISO/IEC 14496-3:2001/AMD-2: Parametric coding for high quality au­dio), aacPlus v2 is the state-of-the-art in low bitrate open standards audio codecs.
The Coding Technologies codecs provide the absolute best possible sound per bit the
current state-of-the-art will allow, without the typical resonant, phasey, watery
character of other codecs.

Trading-Off Audio Bandwidth against Bitrate, Sample rate, and Channel Mode

High audio bandwidth does not guarantee good sound in codecs. In many cases,
especially at low bitrates, it is actually just the opposite. For example, FM radio is a
15 kHz medium, yet there are plenty of codecs claiming to have 20 kHz response
that sound much worse than FM radio.

1-13

The designers of the various codecs usually determine the optimum tradeoff be­tween bitrate, sample rate, and channel mode (stereo or mono) by performing ex­tensive listening tests. To maximize overall audio quality at lower bitrates, it is im­portant to allocate the bits efficiently. This usually means allocating more bits to
those frequency ranges most important to music and speech.

Below a certain sample rate (which depends on the design of the individual codec),
codec designers have determined that limiting audio bandwidth to less than 20 kHz
achieves highest overall quality. For example, AAC requires 192 Kbps or more for 20
kHz+ response (Table 1-2 on page 1-12) and aacPlus requires 64 Kbps or more for 20
kHz+ response (Table 1-1 on page 1-11).

We recommend using aacPlus v2 for stereo streams below 48kbps. Be sure your tar­get players support it; otherwise, the streams will play in mono.

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INTRODUCTION ORBAN MODEL 1010

Cascading Codecs

There are two general applications for codecs in broadcasting — “contribution” and
“transmission.” A contribution-class codec is used in production. Accordingly, it must
have high enough “mask to noise ratio” (that is, the headroom between the actual
codec-induced noise level and the just-audible noise level) to allow its output to be
processed and/or to be cascaded with other codecs without causing the codec­induced noise to become unmasked. A transmission-class codec, on the other hand,
is the final codec used before the listener’s receiver. Its main design goal is maximum
bandwidth efficiency. Some codecs, like Layer 2, have been used for both applica­tions at different bitrates (and Layer 2 continues to be used as the transmission co­dec in the Eureka-147 DAR system and many DBS satellite systems). However, assum­ing use of an MPEG codec, modern practice is to use Layer 2 for contribution only
(minimally at 256 kbps, with 384 kbps preferred), reserving transmission for AAC or
aacPlus. Layer 3 has become a consumer format, and even that is being replaced by
the next generation AAC/HE AAC/aacPlus.

The most general operational advice is this:

• Use compression only when necessary. Hard drives have become very in-
expensive, and there is little excuse for excessively compressing a source li­brary. Linear PCM is best.

• A good codec such as AAC/HE AAC/aacPlus requires a good source to produce
excellent results. If you must use compression in production or transmis-
sion ahead of the audio preprocessor (like Optimod-PC) and have the luxury
of high bitrates, use Layer 2 at 128 kb/sec/channel or above (256 kb/sec
stereo). This will be audibly transparent for as many as ten passes. Avoid
Layer 3 sources; Layer 3 was never rated transparent at any bitrate.

• Do not use a higher sampling frequency than necessary. 32 kHz is ade-
quate for AM, FM. analog television, and low bitrate (~32 kbps) streaming.
However, if you are creating a hard-disk music library and plan to use it for
DAB or high bitrate streaming now or in the future, 44.1 kHz will yield CD­quality bandwidth 20 kHz frequency response. Especially with low bitrate co­decs, a 32 kHz sample rate is generally optimum and sounds better than
higher sample frequencies because the bit allocation for the codec is concen­trated in the most audible region of the audio spectrum. This is a case where
less is truly more.

• Carefully monitor any cascade of codecs by listening tests. There are
an infinite number of combinations possible, and the human ear must be the
final arbiter of quality. Be particularly sensitive to loss of “snap” and transient
definition, loss of stereo imaging, loss of very high frequencies, comb-filtering
or “underwater” sounds, and buildup of distortion.

• Do not use Microsoft Windows Media Player to play MPEG-1 Layer 2
files. There is a confirmed problem with the MPEG-1 Layer 2 decoder filter

used in the current and several past releases of Windows Media Player. This
filter causes a poor signal-to-noise ratio in the form of low-level noise that is
only there when the least significant bits are present. It is audible during quiet
portions of audio and prevents the filter from being usable in professional
applications. Audio signal processing will make this more apparent. We hope
that Microsoft will someday address this issue.

OPTICODEC-PC INTRODUCTION

1-15

Networking

Opticodec-PC supports both unicast and multicast streams. Each method has its own
advantages and your streaming application will determine which one to use.

To connect to the Internet using unicast, a server is required. This receives the out­put of the encoder and creates the streams to which your listeners connect. Optico­dec-PC supplies an output compatible with the free Darwin Streaming Server, which
is available for multiple platforms including Linux®, FreeBSD®, Sun Solaris®, Micro­soft Windows®, and QuickTime Streaming Server for Apple Macintosh®. It is also
compatible with the SHOUTcast DNAS and the Icecast2 servers, also freely
downloadable.

Network Bandwidth Considerations

If you have access to large bandwidth Internet connectivity, you could conceivably
run the server software on your encoder computer—just connect the computer to
an Ethernet Internet feed and you are ready to go. However, most netcasters do not
have that option because the studio or program origination is in one place and the
Internet service provider (ISP) is somewhere else. If that’s the case, the best and most
economical way to connect is to establish what’s called a “co-lo,” or co-location,
which requires running your own server software on another computer, locating
that computer at the ISP, and running one stream per program from your encoder
to the server. Typically, this requires a full-time, non-dial-up dedicated connection
from your encoder to your ISP. Bandwidth requirements for this connection depend
upon the bitrate and number of streams being sent to the server.

A high reliability connection is also recommended to prevent encoder-server discon­nects, although Opticodec-PC has the ability to automatically reconnect when this
occurs. If reliability is the goal, avoid consumer Internet connections, especially cable
Internet and some DSL. The relatively small upload bandwidth available from con­sumer Internet services will severely limit the encoder and/or server. The reliability of
these services is generally not good enough for continuous streaming. Furthermore,
running a server on this type of Internet service may break your Internet service
agreement.

Many ISPs provide servers and administration services to run the appropriate stream­ing server software. Although you are not responsible for the server administration
in this scenario, it comes at a price.

We have just described how to get your program on the network. Here is where the
listeners come in. There are different ways that people can connect to your stream.

• Most Internet streams are implemented via unicasting, which requires a sin-
gle, independent connection to the server for each stream. (See Unicast on
page 1-24.)

• In a multicast, a single stream is shared among the player clients. Although
this technique reduces network congestion, it requires a network that either
has access to the multicast backbone (otherwise called the Mbone) for content
generally distributed over the Internet, or is multicast-enabled for content dis­tributed within a contained private network. Multicast streams are sent di­rectly to a group address, such an IP multicast address, which many client com-

1-16

INTRODUCTION ORBAN MODEL 1010

puters can simultaneously access. The users of a multicast have no control over
the media content. Multicasts are an efficient way to deliver the same mate­rial to a group of people over a LAN, as only one copy of the stream is sent
over the network. (See Multicast on page 1-25.)

Because Opticodec-PC contains a multicast server, more than one listener can
connect to the same IP address without increasing network traffic. This is an
excellent way to deliver corporate or academic content to an internal audi­ence or to stream radio stations to the staff at their computer workstations.
Unless your LAN contains a router that is not multicast enabled and that sepa­rates the encoder from your listeners, you do not need to use a server to mul­ticast within a LAN. For listeners to connect to your stream via a typical LAN,
they have to connect their decoder applications to the same local IP address as
the one you assigned to the output of Opticodec-PC.

Bandwidth Requirements

Streaming puts demand on your server system in a number of ways, the most impor­tant being bandwidth. For example, three different unicast streams for different
purposes will attract different audiences with different network connectivity re­quirements.

Stream Type

Distance Learning
Small Corporate Meeting
Medium Entertainment Stream
Large Entertainment Stream

Attendance

100 20 kbps 2.4 Mbps 990 MB
100 32 kbps 3.8 Mbps 17.1 MB

1000 48 kbps 57.6 Mbps 25.9 GB

5000 48 kbps 288 Mbps 129.6 GB

Audicence
Connection
Speed

Total
Concurrent
Bandwidth + 20%

Total
Throughput
for 1 Hour

Table 1-3: Bandwidth Requirements for Typical Network Streams

Even the smallest academic streams can generate huge numbers that require more
than a single E-1 or T-1 line to serve. Corporate and entertainment streams can
sometimes require multiple E-3 or T-3 lines, or even higher capacity to serve. Large
streams may even require more than one server to handle the necessary network
throughput. However, since Orban Opticodec-PC is bandwidth efficient, you are
able to serve a larger audience at a lower cost of operation with higher audio qual­ity than with inferior older generation codecs.

Not all networks have 100% of their theoretical capacity available for data transfer.
You are practically limited to about 80% of theoretical maximum because of the
way TCP/IP traffic is handled on a network. For example, a 100 Mbps LAN is limited
to about 80 Mbps. In addition to this practical limitation, you may want to allot ad­ditional bandwidth for other tasks, such as file transfers and backup procedures. An
additional 10% should suffice. Generally, a good equation for calculating the practi­cal capacity of a network is:

Practical Network Capacity = Theoretical Maximum * 70%
Maximum Simultaneous Streams = Practical Network Capacity / Stream Bitrate