On 8/7/07, Roman Shpount <[EMAIL PROTECTED]> wrote: > Hi All, > > >>m=audio 9292 RTP/AVP 9 > >>a=rtpmap:9 G722/48000 > >>a=rtpmap:9 G722/56000 > >>a=rtpmap:9 G722/64000 > > This is definitely incorrect. The only clock rate supported by G.722 is > 16KHz, which should be specified as 8KHz for compatibility reasons (see RFC > 3551 4.5.2). This means the offer should be: > > m=audio 9292 RTP/AVP 9 > a=rtpmap:9 G722/8000
So, should we interpret RFC 3551 section 4.5.2 that although RTP clock rate is announced to be 8000Hz in SDP, we should consider it to be 16KHz? Or what else, does G722 considered to be with clock rate 8000Hz in RTP although it is 16 KHz? > > Everything else is not standard and is not supported (except specifying the > number of channels, such as a=rtpmap:9 G722/8000/1). > > Also, there is almost no reason to use any other G.722 bit rate except 64KB. > All of those bit rates actually occupy 64KB of bandwidth. Lower bite rates > simply leave space for a side channel inside the audio stream, which, > IMHO, is not extremely useful in an IP environments. Furthermore, you can > decode all of these bit rates as 64KB with minimal affect on the audio > quality. > > ___________________________________________ > Roman Shpount > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > -- M u r at A r t u n, MSc. Design Engineer "be conservative in what you do, be liberal in what you accept from others" _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
