- From: Bernard Aboba <Bernard.Aboba@microsoft.com>
- Date: Tue, 15 Mar 2016 00:44:13 +0000
- To: Philipp Hancke <fippo@goodadvice.pages.de>, "public-ortc@w3.org" <public-ortc@w3.org>
- CC: Robin Raymond <robin@hookflash.com>, Iņaki Baz Castillo <ibc@aliax.net>, Shijun Sun <shijuns@microsoft.com>
Have submitted PR https://github.com/openpeer/ortc/pull/422 to provide an RTX/RED/FEC example without simulcast. That PR uncovered under-specified aspects of how RTX/RED/FEC works (including retransmission of RED/FEC). Within an RTCRtpReceiver, the example required multiple encodings *without* simulcast (one for the VP8 to be received without RED encapsulation an one to enable VP8 to be received with RED encapsulation). This was needed to specify that RED/FEC was to be retransmitted; the alternative (which seemed even weirder) would be to include encoding parameters for RED. We should probably schedule an ORTC CG meeting to discuss this. It feels awkward :( Since the SDP below is non-standard, I am not sure we can use it in an example, though it would probably not be a bad idea to work up a simulcast and/or SVC example including RTX/RED/FEC. -----Original Message----- From: Philipp Hancke [mailto:fippo@goodadvice.pages.de] Sent: Friday, March 11, 2016 10:52 AM To: public-ortc@w3.org Subject: Re: RED and FEC and RTX (and related questions!) thanks Bernard. How about this SDP which I saw earlier today while using hangouts: m=video 1 RTP/SAVPF 100 96 a=sendrecv a=mid:video a=rtcp-mux a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:1eAjrypb/P7k08KHGrvyMjrieScXdBLdp9L0Ic2A a=rtpmap:100 VP8/90000 a=rtcp-fb:100 ccm fir a=rtcp-fb:100 nack a=rtcp-fb:100 goog-remb a=rtpmap:96 rtx/90000 a=fmtp:96 apt=100 a=rtcp-fb:96 ccm fir a=rtcp-fb:96 nack a=rtcp-fb:96 goog-remb a=extmap:2 urn:ietf:params:rtp-hdrext:toffset a=extmap:3 https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fwww.webrtc.org%2fexperiments%2frtp-hdrext%2fabs-send-time&data=01%7c01%7cBernard.Aboba%40microsoft.com%7cde5d15aea0b544b3a92708d349de742b%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=dS713UEsAuU7vv3hyib1GeNNerxAUPBGoX6DI2pmuAc%3d a=ssrc-group:SIM 2021970535 4198355922 1338462590 a=ssrc-group:FID 2021970535 1247125632 a=ssrc-group:FID 4198355922 3739353240 a=ssrc-group:FID 1338462590 871616995 a=ssrc:2021970535 cname:localCname a=ssrc:2021970535 msid:b6a79d0b-6724-4898-b09e-6be5e154b1d6 1fc51626-7ed8-49fc-821d-64cb2da54a82 a=ssrc:4198355922 cname:localCname a=ssrc:4198355922 msid:b6a79d0b-6724-4898-b09e-6be5e154b1d6 1fc51626-7ed8-49fc-821d-64cb2da54a82 a=ssrc:1338462590 cname:localCname a=ssrc:1338462590 msid:b6a79d0b-6724-4898-b09e-6be5e154b1d6 1fc51626-7ed8-49fc-821d-64cb2da54a82 a=ssrc:1247125632 cname:localCname a=ssrc:1247125632 msid:b6a79d0b-6724-4898-b09e-6be5e154b1d6 1fc51626-7ed8-49fc-821d-64cb2da54a82 a=ssrc:3739353240 cname:localCname a=ssrc:3739353240 msid:b6a79d0b-6724-4898-b09e-6be5e154b1d6 1fc51626-7ed8-49fc-821d-64cb2da54a82 a=ssrc:871616995 cname:localCname a=ssrc:871616995 msid:b6a79d0b-6724-4898-b09e-6be5e154b1d6 1fc51626-7ed8-49fc-821d-64cb2da54a82 a=ice-ufrag:i17XNoOSWNJ+BpfF a=ice-pwd:1fyz+4egEtHK8+AjA3J0/Q4f simulcast with rtx. Looks like an excellent test case :-)
Received on Tuesday, 15 March 2016 00:44:46 UTC