[FFmpeg-trac] #2457(avcodec:new): MAX_SLICES value too low for a number of RTP endpoints

FFmpeg trac at avcodec.org
Thu Apr 11 09:31:23 CEST 2013

#2457: MAX_SLICES value too low for a number of RTP endpoints
             Reporter:  tgreenwood  |                     Type:  defect
               Status:  new         |                 Priority:  normal
            Component:  avcodec     |                  Version:  git-master
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
 When running a stream with RTP endpoints you may receive MAX_SLICES
 errors.  Increasing the value to 64 seems to work without errors on RTP
 endpoints that my colleagues and I have tested.

 You may also notice that this issue is reported by a number of others
 across the internet and 3 bugs have been reported that also note that
 MAX_SLICES was too low among other issues.

 I hope that increasing the value to remove the error messages "increase
 MAX_SLICES and recompile if there are artifacts" is worth it in itself,
 but increasing the value also seems to reduce artefacts. Unfortunately
 I've not captured streams which show artefacts as they occur infrequently
 and our software is not setup to capture streams, this makes it difficult
 to prove that the MAX_SLICES value is the cause.

 The value is found in libavcodec/h264.h and is currently set to 16.  I
 have reported against master, but I know that this value has been 16 in
 previous versions.

 The one client that consistently produces these errors in CounterPath Bria
 and it is the only one I am aware of that ever exceeds 32.

 Please let me know if there is anything further I can do to help.  If
 there is any downside to increasing MAX_SLICES to 64 I'd like to
 understand that as well - Thanks

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2457>
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