Hi Jean,<br>Thats great news for me to start off with as I was planning to go with 16 Kbps ADPCM keeping in mind the issues and options I had. Now, whether the additional computation cost is worth the significant bandwidth savings, I have to see.
<br>Just wondering if it is possible to extend this logic to G3 and G4 fax as well, i.e. using a higher bit-rate and complexity mode for modem or fax instead of going for a higher bit-rate ADPCM.<br>If so, a one stop solution for all kinds of traffic would be awesome.
<br>Thanks a lot for the prompt reply,<br>Mainak<br><br>
<div><span class="gmail_quote">On 5/4/07, <b class="gmail_sendername">Jean-Marc Valin</b> <<a href="mailto:jean-marc.valin@usherbrooke.ca">jean-marc.valin@usherbrooke.ca</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Hi Mainak,<br><br>Speex will definitely be able to handle DTMF. The only question is what<br>the minimum rate for that will be. I remember testing on a few tones at
<br>8 kbps and I didn't hear too much distortion (though there have have<br>been). The only thing I can recommend is to use a higher complexity<br>setting that one would normally use. For voice, I can't really tell the
<br>difference between quality 1 and quality 3, but for DTMF, it actually<br>makes a big difference. I'd recommend using complexity 3 or 4 if you can<br>afford it (in speexenc, you can change that with --comp and the default
<br>is 3).<br><br> Jean-Marc<br><br>Mainak Chakraborty a écrit :<br>> Hi all,<br>> Has anyone tried conveying signaling tones (DTMF) through speex? If so, can<br>> i get an idea of the lowest bit-rate at which I can do so with 'tolerable
<br>> distortion'. G.728 does so and G.729E (11.8 Kbps mode) is 'claimed' to<br>> do so<br>> but even if true, G.729 (rather G.729I - 11.8/8/6.4 kbps) does not allow me<br>> to go below 6.4 kbps if needed. Basically I am looking for a single codec
<br>> which would allow me to play with multiple (low) bit-rates within voice and<br>> switch to a higher bit-rate upon detecting a signaling tone instead of<br>> using<br>> RFC 2833/out-of-band signaling methods. I hope speex is the solution am
<br>> looking for!<br>> Regards,<br>> Mainak<br>><br>> PS: In any case I will have to test it out myself but a positive answer to<br>> this query would definelty brighten up the road ahead :-)<br>><br>
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