[FFmpeg-user] Too much delay/latency in h.264 to MJpeg conversion

Moritz Barsnick barsnick at gmx.net
Wed Jul 26 15:14:08 EEST 2017

On Tue, Jul 25, 2017 at 17:22:29 -0700, Ed Ostertag wrote:
> The command works but the MJpeg images are delayed by over 5 seconds.
> Using local GBit network for the input and loopback for the output so 
> net is not the problem.
> Is there any way to reduce the delay to under 0.5 seconds?

I don't really know much about the latency stuff, but:

> ffmpeg -loglevel debug -fpsprobesize 100 -skip_frame nokey -an  -i 
> rtsp://user:pwd--@ -r 1 -c:v 
> mjpeg -f mjpeg -tune zerolatency -fpsprobesize 100 -s 640x480 -bufsize 0 
> -an "tcp://" 
> 2>>..\..\ffbatlogs\ffbatlog_Cellar_2017_07_25_13_44_03_930.txt

How does it behave if you use a non-network input? (E.g. "-f lavfi -i

How does it behave if you use a non-network output? (E.g.

It might help to understand which side introduces the latency.

> I have an FFmpeg command that creates a stream of jpeg images at 1fps 
> from an h.264 input stream at 20fps. (Key frames only)

Is the input stream "key frames only", or are you demuxing only the key
frames using "-skip_frame nokey"? (I assume the latter, otherwise the
status line would report dropped frames.) Instead of using that option,
which I didn't know until now, perhaps you could try the "select" filter
and see if that changes anything.

  -vf "select='eq(pict_type,I)'"

> [udp @ 0000000000d38aa0] 'circular_buffer_size' option was set but it is not supported on this build (pthread support is required)

I'm not sure whether it matters that your build has no pthread support.

Just guessing,

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