[Icecast] RTP/RTSP streaming of GSM or ADPCM audio

Michael Grigoni michael.grigoni at cybertheque.org
Tue Jun 19 04:30:57 UTC 2007


It would be nice if Icecast supported RTSP; however I would
appreciate any suggestions for a small RTSP/RTP solution to
encode 8kHz mono audio in GSM or ADPCM and service multiple
unicast client connections.  The ideal would be a black-box
hardware solution with an audio input and ethernet interface
similar to broadcast studio IP audio links or the network
audio capabilities of certain X-terminals.  An acceptable
solution would be *nix or Win32 software using PC hardware.
The closest I've found on the 'Net is the old Ulm WebMedia
software from 1997 (win32) but it seems to use a non-standard
RTSP implementation that requires a custom player. There
is a lot of talk on Java discussion forums about coding
this sort of app, but I'd prefer something that did not
need the high overhead of a JVM.

One could use the CCRTP libraries to build such a program
and sample code exists that creates a sender and listener
but nothing like a stream server seems to exist.

For the moment, I've kludged up a SIP UA to service a few
incoming calls in a conference, but that won't scale to a
practical number of listeners.  The Columbia rtspd would work
but does not support GSM or ADPCM without modification; I
don't believe that Apple's server does either.

All replies are much appreciated.



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