[sr-dev] Video Key-Frame Request using RTCP FIR or SIP INFO message

Muhammad Shahzad shaheryarkh at gmail.com
Thu Jan 29 23:56:07 CET 2015


Hi,

This may be a bit out of focus topic for this forum but i am posting it
here anyway with hope that some guru would shed some light on it and point
me to right direction.

The problem is that i want to establish video call between a webrtc and a
sip client using kamailio (for signalling) and RTPEngine (for media relay).
Both signalling and the audio stream seems to work perfectly fine The
remote video on webrtc client side (i.e. video stream from sip client)
takes about 20-30 seconds to establish but once it starts it works fine.
However, the remote video on sip client side (i.e. video stream from webrtc
client) starts almost immediately (within 3-5 seconds) but it gets stuck
after 1 or 2 seconds, then it goes blank after about 30 seconds.

After a long discussion with sip client developer, we now understand the
fact that sip client sends a request for so called key-frame, which is
ignored by webrtc client. This request is sent through both RTCP stream and
SIP INFO message.

The SIP INFO message seems to be pointless as media is internally managed
by chrome/firefox and these browsers don't give us such sophisticated
access and control over media streams. Please let me know if this
assumption is wrong.

For the RTCP stream based request (RTCP-FIR), i only see "Invalid RTCP
packet type" error message in RTPEngine logs (not sure if it drops this
packet or relay it anyway).

Does anyone has any idea on how can we either,

1. Force WebRTC client (running on Chrome / Firefox) to honor SIP INFO
message and issue a key-frame in RTP video stream in response to this SIP
request?

OR

2. Force RTPEngine to accept RTCP-FIR and issue key-frame in RTP video
stream on webrtc client's behalf?

If there is any other solution to this, please feel free to share.


Thank you.
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