Yes it is possible and you can refer to section 5.1 and 7 in the latest draft for reference.
This is not elaborated but it suggests it is certainly possible to do so. It would not have any impact on the media if you are using rtp-pkt-loopback mode acting as loopback-mirror as you cannot generate media but would be useful when acting as loopback-source. Regards, Pravesh On Wed, Aug 4, 2010 at 4:12 PM, Muthu Arul <[email protected]> wrote: > This is certainly possible, even though the draft doesn't state it > explicitly, provided both the loopback-source and loopback-mirror are > capable of sending and receiving the same codec using different RTP payload > types. > > However, the answer from the loopback-mirror can indicate a different > payload type other than what was specified in the "a=loopback-source" line > -- in that case the loopback-source MUST send using the payload type > received in the answer, as specified in section 5.4 of the draft. > > Muthu > > On Wed, Aug 4, 2010 at 12:32 PM, Bharat S <[email protected]> wrote: > >> HI all, >> I have a question on SIP Media Loopback >> >> The SDP format for a SIP Endpoint initiating a loop back call appears as >> below. >> ( As per the draft >> http://tools.ietf.org/html/draft-ietf-mmusic-media-loopback-14) >> >> m=audio 41352 RTP/AVP 0 8 100 >> a=loopback:rtp-media-loopback >> a=loopback-source:0 8 100 >> a=rtpmap:0 pcmu/8000 >> a=rtpmap:8 pcma/8000 >> a=rtpmap:100 G7221/16000/1 >> >> As seen above, two lines ( m line and a=loopback-source) carry the RTP >> payload >> types. When loopback-mode is specified as loopback-source, the media format >> corresponds to the RTP payload types thesource is willing to send. When >> loopback-mode is specified as loopback-mirror, the media format corresponds >> to >> the >> >> RTP payload types the mirror is willing to receive. The payload types >> specified >> in m= line for a loopback-source specify the payloads the source is willing >> to >> receive. >> >> The question is what does it mean if the payload type numbers in m= line >> and >> loopback-source line are different as below? >> >> m=audio 41352 RTP/AVP 112 113 >> a=loopback:rtp-pkt-loopback >> a=loopback-source:0 8 >> a=rtpmap:112 encaprtp/8000 >> a=rtpmap:113 rtploopback/8000 >> >> Can any SIP endpoint ever receive media on some payload types and send >> media on >> a different payload type? The draft doesn't speak much about such a >> scenario. >> >> Many Thanks, >> Bharat >> >> >> >> _______________________________________________ >> Sip-implementors mailing list >> [email protected] >> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors >> > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
