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• How to catch a FFMPEG exception with subprocess ?

  13 mai 2022, par Faindirnomainzein

  I'm doing some work on subtitles and some videos have 1 subtitle track, others have 2 subtitle tracks. For those that have 2, I use the 2nd one (index = 1). I'm trying to automate it with python.

  


  For files with with 2 subtitle tracks, I use :

  


  


  -vf "subtitles='file.mkv':si=1

  


  


  and for those with 1 subtitle track, I use :

  


  


  -vf "subtitles='file.mkv':si=0

  


  


  I'm using this code :

  


  for mkv in all_mkvs:
    try:
      subprocess.call(f'ffmpeg -i ... -vf "subtitles='file.mkv':si=1 ...')
    except:
      subprocess.call(f'ffmpeg -i ... -vf "subtitles='file.mkv':si=0 ...')


  


  But it doesn't seem to care about the exception and just ends the loop whenever it meets a file with 1 subtitle and gives me the error anyway.

  


  Press [q] to stop, [?] for help
[Parsed_subtitles_0 @ 0000011af4912880] Shaper: FriBidi 1.0.10 (SIMPLE) HarfBuzz-ng 2.7.2 (COMPLEX)
[Parsed_subtitles_0 @ 0000011af4912880] Unable to locate subtitle stream in ./test/349.mkv
[AVFilterGraph @ 0000011af623d880] Error initializing filter 'subtitles' with args './test/349.mkv:si=1'
Error reinitializing filters!
Failed to inject frame into filter network: Operation not permitted
Error while processing the decoded data for stream #0:3
Conversion failed!


  


  As you can see in the error message above, it says : "Error initializing filter .... si=1" because it should be si=0 in the case of that specific file, which is why I added the exception, but it doesn't seem to care about it.

  


  

  


  So I'm trying to catch that error and say "ok, in that case, let's do si=0 instead".

  


• Revision 08cdd006e1 : Allow checking zeromv mode in vp9_pick_inter_mode This improves the compression

  22 octobre 2014, par Jingning Han

  Changed Paths :
   Modify /vp9/encoder/vp9_pickmode.c

  
  
  Allow checking zeromv mode in vp9_pick_inter_mode

  This improves the compression performance of speed -5 by 0.6%. The
  speed impact is less than 1%.

  Change-Id : Ie77daa561976dfc8b479061e1221bdf428eb0c3b

• ffmpeg record audio from Xvfb on Centos

  25 mai 2017, par boygiandi

  I’m trying to record audio from Xvfb. And I have some problems :

  1. What’s the different between alsa and pulse. I get confuse
  2. Server Centos have no soud card :

  arecord -l

  arecord : device_list:268 : no soundcards found...

  3. I may have many Xvfb process, how to record video and audio from specific Xvfb process. I checked this https://trac.ffmpeg.org/wiki/Capture/ALSA#Recordaudiofromanapplication but still don’t understand how it works.

  ffmpeg -f alsa -ac 2 -i hw:0,0 -acodec pcm_s16le output.wav

  I seen many command like this, but I don’t know how to get hw:0,0 ( id of sound card ? )

  Please help. Thanks