Inter-M AOE-212N Web-browser interface

AOE-212 Q&A

Prepared by: John Vellone for Inter-M Corp

Server streaming set up mode

Q.What is the meaning of PCM?
A. PCM is Raw Audio (Not Compressed) it uses more bandwidth.

Definition: Pulse-code modulation (PCM) is a method used to digitally represent sampled analog

signals. It is the standard form of digital audio in computers, Compact Discs, digital telephony and
other digital audio applications. In a PCM stream, the amplitude of the analog signal is sampled
regularly at uniform intervals, and each sample is quantized to the nearest value within a range of
digital steps.

Q. What is Unicast/Multi-cast
A. Unicast/Multi-cast selection only applies to PCM only
(1) Uni-cast is one to one Bi-directional One server to max 20 clients. LAN/WAN
(2) Multi-cast is one to N. One direction only LAN ( No Routing)
If you use C class, IP adress Strategy, 254 clients are possible.
Ex.: SUB NET 255.255.255.0 ( 254 possible IP adress)
With Advanced router configuration it is possible to have more clients.

Unicast Definition: Unicast

Unicast is the term used to describe communication where a piece of information is sent from one
point to another point. In this case there is just one sender, and one receiver.

Unicast transmission, in which a packet is sent from a single source to a specified destination, is
still the predominant form of transmission on LANs and within the Internet. All LANs (e.g. Ethernet)
and IP networks support the unicast transfer mode, and most users are familiar with the standard
unicast applications (e.g. http, smtp, ftp and telnet) which employ the TCP transport protocol.

Broadcast Definition:

Broadcast is the term used to describe communication where a piece of information is sent from
one point to all other points. In this case there is just one sender, but the information is sent to all
connected receivers.

Broadcast transmission is supported on most LANs (e.g. Ethernet), and may be used to send the
same message to all computers on the LAN (e.g. the address resolution protocol (arp) uses this to
send an address resolution query to all computers on a LAN). Network layer protocols (such as
IPv4) also support a form of broadcast that allows the same packet to be sent to every system in a
logical network (in IPv4 this consists of the IP network ID and an all 1's host number).

Multicast Definition:

Multicast is the term used to describe communication where a piece of information is sent from one
or more points to a set of other points. In this case there is may be one or more senders, and the
information is distributed to a set of receivers (theer may be no receivers, or any other number of
receivers).

One example of an application which may use multicast is a video server sending out networked
TV channels. Simultaneous delivery of high quality video to each of a large number of delivery
platforms will exhaust the capability of even a high bandwidth network with a powerful video clip
server. This poses a major salability issue for applications which required sustained high
bandwidth. One way to significantly ease scaling to larger groups of clients is to employ multicast
networking.

Multicasting is the networking technique of delivering the same packet simultaneously to a group of
clients. IP multicast provides dynamic many-to-many connectivity between a set of senders (at
least 1) and a group of receivers. The format of IP multicast packets is identical to that of unicast
packets and is distinguished only by the use of a special class of destination address (class D IPv4
address) which denotes a specific multicast group. Since TCP supports only the unicast mode,
multicast applications must use the UDP transport protocol.

Unlike broadcast transmission (which is used on some local area networks), multicast clients
receive a stream of packets only if they have previously elect to do so (by joining the specific
multicast group address). Membership of a group is dynamic and controlled by the receivers (in
turn informed by the local client applications). The routers in a multicast network learn which sub­networks have active clients for each multicast group and attempt to minimise the transmission of
packets across parts of the network for which there are no active clients.

The multicast mode is useful if a group of clients require a common set of data at the same time, or
when the clients are able to receive and store (cache) common data until needed. Where there is a
common need for the same data required by a group of clients, multicast transmission may provide
significant bandwidth savings (up to 1/N of the bandwidth compared to N separate unicast clients).

The majority of installed LANs (e.g. Ethernet) are able to support the multicast transmission mode.
Shared LANs (using hubs/repeaters) inherently support multicast, since all packets reach all
network interface cards connected to the LAN. The earliest LAN network interface cards had no
specific support for multicast and introduced a big performance penalty by forcing the adaptor to
receive all packets (promiscuous mode) and perform software filtering to remove all unwanted
packets. Most modern network interface cards implement a set of multicast filters, relieving the
host of the burden of performing excessive software filtering.
Q. When should RTSP be used?
A. RTSP uses MP3 128kbps compression. It uses less bandwidth than PCM

Q.: When do I use Channel 1 or Channel 2?
A.: This selection allows the AOE to be used as a Mono Single Channel streamer (CH 1 means
one Channel) or Stereo, (Ch2 means two chanels). If using only one channel then ‚select channel
Ch1‘ this will shut down channel 2 and reduce bandwidth.