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[Linphone-users]Re: TrueSpeech codec

From: Robert W. Brewer
Subject: [Linphone-users]Re: TrueSpeech codec
Date: Mon, 26 May 2003 12:28:34 -0400
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20021226 Debian/1.2.1-9

Simon Morlat wrote:

This is a very nice solution. I think the Yahoo messenger should then
initiate a SIP call to linphone and put in the SDP message the correct
settings (port, codec). Then the user would ring and the user would have
to accept the call as normally. The Yahoo messenger would receive the
200 Ok from linphone and then do the necessary signaling to the remote
Yahoo messenger. Doing as this, linphone does not need any modifications
in its interfaces.
Ahh, that does sound like a nice way to do it. I didn't realize SIP/SDP could specify ports anywhere they wanted, but I guess that makes sense for things like call transfer. I'm actually not totally sure what the use case would be like, there are at least two different ones on Yahoo... point-to-point voice chat with one other person and voice chat in a conference room. The conference room uses Yahoo's server as a reflector, I think point-to-point can go direct to the other IP or through the server. It probably doesn't matter much to Linphone as long as it's told where to go. If we get to this scheme it might be useful to have a way of doing auto-answer in Linphone (maybe configurable by the user from only trusted sources?). This would allow the user to approve the call in the messenger and not be bothered pressing another button in Linphone to get it going. But something like that is still a ways off... :)

I would be very interested in having this dll support in linphone.
That's why I suggest the following:
First step:
* you add support for TrueSpeech codec in linphone, I can take in charge
the signaling side for this codec (all code that is not in
mediastreamer/), if you wish
* you take the linphone code into your messenger to test all that.

Second step:
* you implement the Yahoo-to-SIP call forwarding. If you need help, I'm

What do you think of that ?
I can provide you rw access to linphone's cvs, to avoid wasting time in
merging patches.
Note that linphone-0.11.0 is already deprecated compared to the cvs
code... No changes in mediastreamer, but some important changes in the
way linphone understands codecs.
I'm waiting for your comments.
Ok, I think that's a good way forward. We've got encoding and decoding of TrueSpeech files under Linux today, so putting a TrueSpeech codec in Linphone is the next step. Once it's in it shouldn't be too hard for those interested to add other codecs supported by Microsoft's ACM (Audio Compression Manager). The main thing needed is to create some test .wav files under Windows to find out the correct headers to configure the .dll. Mplayer's codecs.conf is helpful for finding the right .dll to load. :) I'll include a note about this with the code.

I pulled down the CVS. I intend to add msTrueSpeechencoder.*, msTrueSpeechdecoder.*, test_truespeech.c, and a separate directory for all the .dll loading infrastructure. I haven't yet located how to register a new codec with the rest of the code, is that the signalling you're describing? It may be a couple weeks before I can get this added. My savannah account is rbrewer if you'd like to add me. Thanks.


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