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MakIng EBU 3326/SIP CoMPatIBlE ConnECtIonS
Comrex codecs (and many other brands) have a set of protocols that allow easy IP connections between units. In
general, when connecting between Comrex hardware, it’s best to use these proprietary modes to take the most
advantage of the features of the product.
However, many users are concerned about getting “locked in” to a certain codec brand. Because of this, an
international committee was formed by the European Broadcast Union called N/ACIP to hammer out a common
protocol to interconnect codec brands. This committee resulted in the establishment of EBU 3326, a technical
document which determined standards for codec compatibility.
EBU 3326 by and large establishes a set of features each codec should support, then leaves most of the heavy lifting
to other, previously agreed upon standards like SIP (IETF RFC 3261). Topics not yet covered by EBU 3326 include
things like carrying ancillary data and contact closures from end-to-end, codec remote control and monitoring, and
complex NAT traversal, which at this point are still left to the individual manufacturer’s discretion. This is why it’s
best to stick to a single codec vendor and their proprietary protocols.
MorE aBoUt EBU 3326
The Tech 3326 document defines several mandatory encoding algorithms, and the transport layer that could be
used on them for compatibility. However, the most complex part of the standard was the decision on how to
arrange Session Initialization, which is the handshake that takes place at the start of an IP codec call. The most
commonly used protocol for this is called Session Initialization Protocol, or SIP. This is used extensively by VoIP
phones and therefore was a logical choice. SIP carries the advantage of making ACCESS compatible with a range of
other non-broadcast products, like VoIP hardware, software, and even mobile phone apps.
EBU 3326 In aCCESS
ACCESS does not fully comply with EBU 3326, as it does not feature the mandatory MPEG Layer II codec. Aside from
this, ACCESS has been tested to be compatible with several other manufacturer’s devices using encoders supported
by both products. When using
EBU 3326/SIP Compatible
mode (this is how the user interface describes EBU 3326),
ancillary data, contact closures, Switchboard TS, Multi-streaming and Multicasting are not supported. Outgoing
call profiles built with the EBU 3326/SIP channel may lack some advanced options, and can not be set for different
encoders in each direction (i.e. EBU 3326/SIP calls are always symmetrical).
EBU 3326/SIP ModES
A function of placing a SIP-style call is the ability to register with a SIP server. This is a server that exists somewhere
on the network, usually maintained by a service provider. Several free servers exist that can offer registration like
Onsip.com
.
Содержание ACCESS 2USB
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