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• avformat_open_input crash using ffmpeg on android

  2 octobre 2019, par Timmy K

  I am writing an Android app to capture audio streams from a USB device using ffmpeg, and mux them into an m4a file. I then open the recording file to read back the audio data. The app works fine on Samsung S8 (Android 8.0) and S9 (Android 9.0). On a Moto G5+ (Android 8.1), however the app crashes inside avformat_open_input() when I try to open the recording file ; but if I restart the app and it reads the same file with the same code, it works without crashing.

  I thought maybe that I hadn’t closed the recording file properly ; or there was maybe a race condition : trying to read the file before it was written. However I have established that av_write_trailer() is called successfully and avio_closep() is called successfully before the call to avformat_open_input. I also established that the length of the file is the same just before the call to avformat_open_input() in the crash case as it is in the non-crash case.

  The code that finishes the recording :

  // AVFormatContext *mAvFormatContext
  
  // ...
  
  int ret = av_write_trailer(mAvFormatContext);
  
  if ( ret != 0 )
  
  {
  
      __android_log_print(ANDROID_LOG_DEBUG, "MyTag", "failed to write trailer %s", av_err2str( ret ) );
  
      goto fail;
  
  }
  
  
  
  ret = avio_close( mAvFormatContext->pb );
  
  if ( ret < 0 )
  
  {
  
      __android_log_print(ANDROID_LOG_DEBUG, "MyTag", "failed to avio_close %s", av_err2str( ret ) );
  
      goto fail;
  
  }
  
  
  
  avformat_free_context(mAvFormatContext);

  The call that causes a crash immediately after the above code, on a Moto 5G+ (but not Samsung S8/S9) :

  mAvFormatContext = nullptr;
  
  if ( (ret = avformat_open_input( &mAvFormatContext, filePath, 0, 0)) < 0 )
  
  {
  
      __android_log_print(ANDROID_LOG_DEBUG, "MyTag++", "Could not open input file '%s' error %s ", filePath, av_err2str(ret) );
  
      cleanup();
  
      return false;
  
  }

  Also, when the call to avformat_open_input() does not crash, there is no output in logcat from within that call. However, I’ve noticed that in the crash case there is output of what seems to be corrupted data :

  2019-09-02 09:39:14.105 19999-19999/fm.x.y D/AudioEngine: Opening '@�7���-d��@�7�' for 
  
  2019-09-02 09:39:14.106 19999-19999/fm.x.y D/AudioEngine: Setting default whitelist '<��'
  
  2019-09-02 09:39:14.106 19999-19999/fm.x.y D/AudioEngine: Probing ���d score:-1828887548 size:-1093138844
  
  2019-09-02 09:39:14.106 19999-19999/fm.x.y D/AudioEngine: Format ��� probed with size=-1093138756 and score=-1093138748
  
  (crash occurs)

  Any advice on what to look into further to investigate this problem ? Is there something I am missing when cleaning up the muxing state before I try to open the recording file for demuxing ? For simplicity I have not included the freeing of codec contexts, AVFrames and AVPackets.

• Video created via ffmpeg will not play on iPhone 10 or Huawei Android using Chrome

  17 février 2020, par MHatton

  I have created a video from a image and adding an MP3 file. It plays fine on my Moto G Android phone and on my desktop, but a collegue has said it will not play on his iPhone 10 or Huawei Android phone running Chrome.

  Does the following ffmpeg need an extra command adding to make the created MP4 more compatible across devices ?

  ffmpeg -loop 1 -i 6f4aa5dfefc4dd32186f41315ad9d1e2-0.png -i "download.mp3" -c:v libx264 -tune stillimage -c:a aac -b:a 192k -pix_fmt yuv420p -shortest aw-slide0.mp4

• mp4 video rotation metadata removal

  6 mars 2019, par Horst Fiedler

  Using ffmpeg to remove rotate metadata works but output is little bit confusing as Metadata : rotate : 90 still appears in output section.

  ffmpeg version N-92663-g8affd75

  seems to keep rotate metadata :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'vid_20190302_162804987.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2019-03-02T15:28:43.000000Z
  
      com.android.version: 6.0.1
  
    Duration: 00:00:32.40, start: 0.000000, bitrate: 17230 kb/s
  
      Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 17003 kb/s, SAR 1:1 DAR 16:9, 28.98 fps, 29.33 tbr, 90k tbn, 180k tbc (default)
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2019-03-02T15:28:43.000000Z
  
        handler_name    : VideoHandle
  
        encoder         : MOTO
  
      Side data:
  
        displaymatrix: rotation of -90.00 degrees
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
  
      Metadata:
  
        creation_time   : 2019-03-02T15:28:43.000000Z
  
        handler_name    : SoundHandle
  
  Output #0, mp4, to '1.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      com.android.version: 6.0.1
  
      encoder         : Lavf58.24.100
  
      Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 17003 kb/s, 28.98 fps, 29.33 tbr, 90k tbn, 90k tbc (default)
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2019-03-02T15:28:43.000000Z
  
        handler_name    : VideoHandle
  
        encoder         : MOTO
  
      Side data:
  
        displaymatrix: rotation of -0.00 degrees
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
  
      Metadata:
  
        creation_time   : 2019-03-02T15:28:43.000000Z
  
        handler_name    : SoundHandle

  but fortunatly the rotate is missing in succeeding ffmpeg (or ffprobe)