H264 streaming with variable / adpative bitrate streams

[Hokoha Team]

Dear all,

Maybe one silly question : we implement right now streaming plugin for variable / adpative bitrate streams and H264 codec.

"Frozen scenes" occur when pictures change quickly (if new people appears for example).

Is there specific settings in Janus (buffer size frame ?) to prevent for such inconvenience ?

Many thanks by advance !

Laurent C.

[Alessandro Toppi]

How do you know it is due to janus and not to the media source or congestion issues?

I'd first check that media coming out from the source is ok by either inspecting the process output (ffmpeg/gstreamer) or the RTP received on the mountpoint (tcpdump).

[Hokoha Team]

You are right : that's what we did by checking the stream on VLC for example but it is purelly visual.

And it seems to be correlated, each time, to some important changes on picture.

We also check with Wireshark and we saw nothing special but perhaps are we not looking to the relevant items : what could be the right info to check in order to know if the media source is smooth enough ?

One more thing : we are using UDP protocol for our streaming.

Thanks by advance,

Laurent C.

[Alessandro Toppi]

The change of picture implies an adaptation of the encoder and a potential peak in bitrate.

Try to modify some encoding parameters e.g. set it to zero latency / real time, lower the bitrate, increase keyframe interval etc. and see if it helps.

Checking the RTP inbound traffic on the mountpoint means analyzing how delta times change, checking packet loss and ordering, relating the RTP timestamps with wall clock etc.

[Hokoha Team]

Thanks a lot : I will chekc all that point and keep you informed !

Best regards,

Laurent C.