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• FFmpeg auto rotate video when copying video stream without re-encoding

  25 février 2019, par Mahfujur Rahman

  I have been trying to convert an mp4 (portrait) file to mkv. As the mkv container support any video and audio stream, I am copying the audio and video stream to the output container. The command I’m using

  ffmpeg -y -i test.mp4 -vcodec copy -acodec copy test.mkv

  File info for test.mp4 is following

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2019-02-23T11:18:50.000000Z
  
      com.android.version: 8.0.0
  
    Duration: 00:00:25.86, start: 0.000000, bitrate: 12270 kb/s
  
      Stream #0:0(eng): Video: h264 (avc1 / 0x31637661), yuv420p(tv, bt709), 1280x720, 12005 kb/s, SAR 1:1 DAR 16:9, 30 fps, 30 tbr, 90k tbn, 180k tbc (default)
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2019-02-23T11:18:50.000000Z
  
        handler_name    : VideoHandle
  
      Side data:
  
        displaymatrix: rotation of -90.00 degrees
  
      Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 256 kb/s (default)
  
      Metadata:
  
        creation_time   : 2019-02-23T11:18:50.000000Z
  
        handler_name    : SoundHandle

  Now, the problem is that the output video I get from ffmpeg is a 90 degree counter clockwise rotated video. The reason I believe is the following info being removed from output file,

  Side data:
displaymatrix: rotation of -90.00 degrees

  File info for rotated output file test.mkv

  Input #0, matroska,webm, from 'test.mkv':
  
    Metadata:
  
      MAJOR_BRAND     : mp42
  
      MINOR_VERSION   : 0
  
      COMPATIBLE_BRANDS: isommp42
  
      COM.ANDROID.VERSION: 8.0.0
  
      ENCODER         : Lavf58.12.100
  
    Duration: 00:00:25.87, start: 0.000000, bitrate: 12265 kb/s
  
      Stream #0:0(eng): Video: h264, yuv420p(tv, bt709, progressive), 1280x720, SAR 1:1 DAR 16:9, 30 fps, 30 tbr, 1k tbn, 2k tbc (default)
  
      Metadata:
  
        ROTATE          : 90
  
        HANDLER_NAME    : VideoHandle
  
        DURATION        : 00:00:25.866000000
  
      Stream #0:1(eng): Audio: aac, 48000 Hz, stereo, fltp (default)
  
      Metadata:
  
        HANDLER_NAME    : SoundHandle
  
        DURATION        : 00:00:25.813000000

  But when I convert this rotated output test.mkv to mp4 again, I get the portrait file. The displaymatrix side data appears again in the file info.

  Converting the same mp4 file to m4v by copying the steam works fine.

  So, this whole thing is very much confusing to me.

  Now my question is, how can I convert the mp4 file to mkv without re-encoding and avoid getting rotated output ?

  In this post they solved it for c++. I am working on android and using ffmpeg android wrapper to use the ffmpeg library. Is there any ffmpeg flag to handle this situation ?

• Anomalie #4257 : Impossible de lire certaines descriptions XML et validation XML bloquée par écran...

  15 février 2019

  On peut peut-être au moins corriger le lien pour qu’il pointe au bon endroit, non ? (même si le bon endroit ne marche pas).

• lavc : factor out encoder init/validation from avcodec_open2()

  9 mars 2021, par Anton Khirnov

  lavc : factor out encoder init/validation from avcodec_open2()
  avcodec_open2() is massive, splitting it makes it more readable.
  Also, add a missing error code to ticks_per_frame sanity check.
  

  • [DH] libavcodec/encode.c
  • [DH] libavcodec/encode.h
  • [DH] libavcodec/utils.c