README.g728

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This file provides information on enabling G.728 support in RAT.
Please do not make binaries containing G.728 available to the public
without consulting the G.728 intellectual property right owners.  We
have added support for evaluation purposes only.
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G.728 support is provided by a wrapper around the publicly available
encoding and decoding routines by Alex Zatsman (with additions
by Michael Concannon).

The G.728 wrapper can be found on the UCL multimedia cvs server.  The
module is named "g728lib".  Details on accessing the server may be
found at:

	http://www-mice.cs.ucl.ac.uk/multimedia/software/cvsanon.html

The modules rat, common, g728lib should be extracted into the same
directory.  g728lib needs building first to allow RAT's configure
script to detect it and put the appropriate pieces into the Makefile.

We have not made any modifications to the underlying encoding and
decoding functions in Alex's package.  The functions use static
variables to contain state and therefore limit the number of instances
that should be run per process to 1.  Running more instances
simultaneously will lead to state corruption and degradation of the
audio stream quality.  For point-to-point communication this should
not be a major issue if silence suppression is used.  Echo
suppression (network-mutes-mic operation) will also help.

When using G.728 it is worth considering that it has an exceptionally
small frame size (0.625ms).  We recommend using 32 or 64 units (frames)
per packet to get a reasonable amount of G.728 data into each RTP packet.

	32 units (frames) per packet -> 20ms audio per packet
	64 units (frames) per packet -> 40ms audio per packet

Enjoy!