[Ffmpeg-devel] mp4v rate control problems

Oivind oivindg
Thu Feb 16 16:10:55 CET 2006

I am having problems with ffmpeg rate control on my 2mbit/s mp4v
transcoded udp multicast stream using latest CVS of ffmpeg and VLC
streamer. The source is a standard mpeg2 ts coming from satellite tv

Without any rate control, I am seeing huge bursts (from hardware mpeg
ip probe) measured in 250ms periods up to 25mbit/s. With rate control
of strict-rc and default aggressiveness/buffer, it seems that I am
getting a few frames of large macroblocks arriving on every keyframe,
with a more constant bitrate -- I wonder if this is a known problem
and whether anyone is working on it? Is there is anything I could do
in the encoder to prevent bursts of that magnitude? My transcoder is
running in rt-priority. I also heard that the bitrate tolerance isn't
working (and doesn't seem to be working during tests).

As a last resort, I am thinking about setting up leaky bucket shaping
in the kernel and expanding the udp-buffer on clients. Bursts seem to
have small enough period for this to work (the average bitrate is
fine). Any comments here?


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