[Libav-user] [FFmpeg-user] ffmpeg burst traffic problem

Zach Swena zcybercomputing at gmail.com
Sun Oct 18 21:49:35 CEST 2015

In general hardware decoders have a problem with the bursty nature of
FFmpeg's UDP.  I have fixed this by buffering to disk and sending it with
my own program.  ISO131808-1 does not specify the maximum jitter allowable
in packets, but I have found up to 500 micro seconds to be acceptable for a
4mbps mux.  The problem is bursty UDP datagrams cause underflow and
overflow of the input buffer in hardware decoders.

The pacing solution I used for my own program was to make an event loop
thread that only ever performs "short" operations.  This thread is simply a
loop which checks a timer with nanosecond resolution.  If it is less then
1/3 the way through the period, I process other operations, but as it nears
the time to transmit, it just functions as a simple wait loop.  We really
need someone familiar with the UDP code to rework the transmit pacing.


On Fri, Oct 16, 2015 at 9:21 AM, julian at jusst.de <julian at jusst.de> wrote:

> > I had a patch once that would "slow down" udp output if you'd like to
> > try it...what is the problem though, are you unable to receive it on
> > the receiving side?
> Do you happen to still have that patch around? I just ran into a problem
> where ffmpegs udp output is too bursty for the used receiver. Would be
> interesting to try your patch.
> -Julian
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