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• avformat/vobsub : fix several issues.

  29 septembre 2013, par Clément Bœsch

  avformat/vobsub : fix several issues.
  Here is an extract of fate-samples/sub/vobsub.idx, with an additional
  
  text at the end of each line to better identify each bitmap :
      timestamp : 00:04:55:445, filepos : 00001b000 Ace !
  
      timestamp : 00:05:00:049, filepos : 00001b800 Wake up, honey !
  
      timestamp : 00:05:02:018, filepos : 00001c800 I gotta go to work.
  
      timestamp : 00:05:02:035, filepos : 00001d000 < ???>
  
      timestamp : 00:05:04:203, filepos : 00001d800 Look after Clayton, okay ?
  
      timestamp : 00:05:05:947, filepos : 00001e800 I’ll be back tonight.
  
      timestamp : 00:05:07:957, filepos : 00001f800 Bye ! Love you.
  
      timestamp : 00:05:21:295, filepos : 000020800 Hey, Ace ! What’s up ?
  
      timestamp : 00:05:23:356, filepos : 000021800 Hey, how’s it going ?
  
      timestamp : 00:05:24:640, filepos : 000022800 Remember what today is ? The 3rd !
  
      timestamp : 00:05:27:193, filepos : 000023800 Look over there !
  
      timestamp : 00:05:28:369, filepos : 000024800 Where are they going ?
  
      timestamp : 00:05:28:361, filepos : 000025000 < ???>
  
      timestamp : 00:05:29:946, filepos : 000025800 Let’s go see.
  
      timestamp : 00:05:31:230, filepos : 000026000 I can’t, man. I got Clayton.
  Note the two "< ???>" : they are basically split subtitles (with the
  
  previous one), which the dvdsub decoder is now supposed to reconstruct
  
  with a previous commit. But also note that while the first chunk has
  
  increasing timestamps,
      timestamp : 00:05:02:018, filepos : 00001c800
  
      timestamp : 00:05:02:035, filepos : 00001d000
  ...it’s not the case of the second one (and this is not an exception in the
  
  original file) :
      timestamp : 00:05:28:369, filepos : 000024800
  
      timestamp : 00:05:28:361, filepos : 000025000
  For the dvdsub decoder, they need to be "filepos’ed" ordered, but the
  
  FFDemuxSubtitlesQueue is timestamps ordered, which is the reason of the
  
  introduction of a sub sort method in the context, to allow giving
  
  priority to the position, and then the timestamps. With that change, the
  
  dvdsub decoder get fed with ordered packets.
  Now the packet size estimation was also broken : the filepos differences
  
  in the vobsub index defines the full data read between two subtitles
  
  chunks, and it is necessary to take into account what is read by the
  
  mpegps_read_pes_header() function since the length returned by that
  
  function doesn’t count the size of the data it reads. This is fixed with
  
  the introduction of total_read, and old,new_pos. By doing this change,
  
  we can drop the unreliable len16 heuristic and simplify the whole loop.
  
  Note that mpegps_read_pes_header() often read more than one PES packet
  
  (typically in one call it can read 0x1ba and 0x1be chunk along with the
  
  relevant 0x1bd packet), which triggers the "total_read + pkt_size >
  
  psize" check. This is an expected behaviour, which could be avoided by
  
  having a more chunked version of mpegps_read_pes_header().
  The latest change is the extraction of each stream into its own
  
  subtitles queue. If we don’t do this, the maximum size for a subtitle
  
  chunk is broken, and the previous changes can not work. Having each
  
  stream in a different queue requires some little adjustments in the
  
  seek code of the demuxer.
  This commit is only meaningful as a whole change and can not be easily
  
  split. The FATE test changes because it uses the vobsub demuxer.
  

  • [DH] libavformat/mpeg.c
  • [DH] libavformat/subtitles.c
  • [DH] libavformat/subtitles.h
  • [DH] tests/ref/fate/sub2video

• Any way to assign terminal output to variable with python ?

  15 août 2022, par Gordon Fontenot

  I need to grab the duration of a video file via python as part of a larger script. I know I can use ffmpeg to grab the duration, but I need to be able to save that output as a variable back in python. I thought this would work, but it's giving me a value of 0 :

  



  cmd = 'ffmpeg -i %s 2>&1 | grep "Duration" | cut -d \' \' -f 4 | sed s/,//' % ("Video.mov")
duration = os.system(cmd)
print duration


  



  Am I doing the output redirect wrong ? Or is there simply no way to pipe the terminal output back into python ?

  


• How to specify a path for output file in ffmpeg ?

  29 janvier 2020, par Karthikeya Vaidya

  I am trying to give a path for the output file, but ffmpeg is giving an error stating

  Unable to find a suitable output format for ’/kcs/eng/ : Invalid argument.

  Whereas it is accepting the full path of the input file.

  $in_path = "D:/kcs/kan/video.vob";
  
  $out_path = "E:/kcs/eng/video.mp4";
  
  
  
  ffmpeg -i $in_path -loglevel error -c:v libx264 -c:a aac -strict experimental $out_Path 

  How to specify the path of the output file ?