Hi, I've got a few questions and perhaps a problem or two with using codecs in SEMS 1.2.1
Is there any rate conversion between files stored on disk in WAV format and the line rate? In my case I have a 16000 Hz wav file and am using G711 codec. The played out sound is very slow, so even though SEMS reads the file as 16000 Hz (as per debug) The delivered rate assumes 8000 Hz so the sound is half speed. I am a bit surprised there is no rate conversion, so I would like to know if there is a flag I have to set? I am trying to use G726-32 codec for some communications. The behaviour is very odd The debug shows the call phone requesting G726_32 Content-Type: application/sdp P-App-Param: usr=12345 v=0 o=- 7373316 7373316 IN IP4 203.31.40.160 s=- c=IN IP4 203.31.40.102 t=0 0 m=audio 8020 RTP/AVP 2 101 a=rtpmap:2 G726-32/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-15 a=ptime:30 a=sendrecv a=nortpproxy:yes (I'm using rtpproxy for recording which causes a minor and inaccurate problem from the nortpproxy line) The reply is Content-Type: application/sdp Content-Length: 198 v=0 o=sems 1219929049 1248189210 IN IP4 203.31.40.68 s=session c=IN IP4 203.31.40.68 t=0 0 m=audio 8000 RTP/AVP 2 101 a=rtpmap:2 G721/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-15 Where it seems SEMS has substituted G721 for G726_32 ? Is this an error? (This shows up on wireshark as well) At this stage I get a protocol error on the phone. At various stages of testing I've got sound through but just as noise. Does SEMS require the wav file to be in the same format as the line format? or can it transcode? Can it rate convert when codecs are different. I can work around all these problems by using G711 and 8000 Hz wav files, but being able to work at G726-32 would be very helpful, as would automatic rate conversion. Thanks in advance Jeremy _______________________________________________ Sems mailing list [email protected] http://lists.iptel.org/mailman/listinfo/sems
