[FFmpeg-devel] FFMPEG RTCP Receiver Report Analysis

Luca Abeni lucabe72
Mon Apr 20 22:14:37 CEST 2009

On Fri, 2009-04-17 at 22:23 +0100, Roberto Nunes wrote:
> I was wondering if anyone could give me an explanation on how FFMPEG
> controls the bitrate when its streaming video using rtp protocol.

It does not

> Seems that the bitrate and fps (frames per second) are controled via the
> RTCP receiver reports.

No; RTCP receiver reports just contain some information about the RTT,
jitter, packet loss, etc... experienced by the various RTP packets.
An RTP streamer could use these information to adapt the bitrate, but
this is up to the application and is not specified by the standard.

> I was wondering how it is done, i.e. which fileds of RTCP RR packet is used
> and how is the bitrate (of encoded video) calculated in this matter.

This depends on the policy you want to implement in the RTP streamer (if
you want to implement some adaptation policy). You can google for
"equation based congestion control" to get some ideas.

BTW, if you want to implement something like this the correct place
might be ffserver, not ffmpeg.


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