Chrome Version       : 49
URLs (if applicable) :
OS version               : All
Network (such as Cable/DSL/Dial up etc):
Audio/Video format (if applicable): WebRTC
Special chrome flags (if applicable):


For various reasons, we at Blackboard would like to synchronise several video tracks with a single audio track. My understanding of the specification is that it should be possible to place these all in one MediaStream and have them all synchronised. However I am seeing in the output log the line:

Attempting to sync more than one audio/video pair within the same sync group. This is not supported in the current implementation.

So, my question is, how long to implement?


Some background, we are sending an SDP similar to:

a=msid-semantic: WMS rgMeZLPaW1Ac1pLrAnqZ
m=audio 51500 UDP/TLS/RTP/SAVPF 99 107 103 102 106 98 101
a=sendrecv
...
a=ssrc:2371673378 msid:rgMeZLPaW1Ac1pLrAnqZ 8RBCQkUaKcsAjJMFHE7a
a=ssrc:2371673378 cname:toaGdmSdVh+FwwBQVodgeA
a=ssrc:2371673378 mslabel:rgMeZLPaW1Ac1pLrAnqZ
a=ssrc:2371673378 label:8RBCQkUaKcsAjJMFHE7a
m=video 51500 UDP/TLS/RTP/SAVPF 104 105 109 108 114 34 100
...
a=ssrc:434294564 msid:rgMeZLPaW1Ac1pLrAnqZ MIy7e7ULrRBracjlCaBX
a=ssrc:434294564 cname:tjGGdmSdVh+FvwBQVodgeA
a=ssrc:434294564 mslabel:rgMeZLPaW1Ac1pLrAnqZ
a=ssrc:434294564 label:MIy7e7ULrRBracjlCaBX
a=ssrc:601342679 msid:rgMeZLPaW1Ac1pLrAnqZ EuObXluT1M2IvowakpYU
a=ssrc:601342679 cname:0HGGdmSdVh+FwgBQVodgeA
a=ssrc:601342679 mslabel:rgMeZLPaW1Ac1pLrAnqZ
a=ssrc:601342679 label:EuObXluT1M2IvowakpYU
a=ssrc:902297578 msid:rgMeZLPaW1Ac1pLrAnqZ imNo06s4Fhyi8vxeIlb6
a=ssrc:902297578 cname:rlyGdmSdVh+FwQBQVodgeA
a=ssrc:902297578 mslabel:rgMeZLPaW1Ac1pLrAnqZ
a=ssrc:902297578 label:imNo06s4Fhyi8vxeIlb6
a=ssrc:1947266820 msid:rgMeZLPaW1Ac1pLrAnqZ ZQqFLFQz5APOqZCWKsCM
a=ssrc:1947266820 cname:qkeGdmSdVh+FwABQVodgeA
a=ssrc:1947266820 mslabel:rgMeZLPaW1Ac1pLrAnqZ
a=ssrc:1947266820 label:ZQqFLFQz5APOqZCWKsCM

So, all 5 tracks (4 video, 1 audio) are in MediaStream with id rgMeZLPaW1Ac1pLrAnqZ

This is accepted by Chrome, but there is no lip synch being performed.