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• Call to avformat_find_stream_info prevents decoding of simple PNG image ?

  10 avril 2014, par kloffy

  I am running into a problem decoding a simple PNG image with libav. The decode_ok flag after the call to avcodec_decode_video2 is set to 0, even though the packet contains the entire image. Through some experimentation, I have managed to pinpoint the issue and it seems related to calling avformat_find_stream_info. If the call is removed, the example runs successfully. However, I would like to use the same code for other media, and calling avformat_find_stream_info is recommended in the documentation.

  The following minimal example illustrates the behavior (unfortunately still a bit lengthy) :

  #include <iostream>
  
  
  
  extern "C"
  
  {
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  }
  
  
  
  // Nothing to see here, it&#39;s just a helper function
  
  AVCodecContext* open(AVMediaType mediaType, AVFormatContext* formatContext)
  
  {
  
      auto ret = 0;
  
      if ((ret = av_find_best_stream(formatContext, mediaType, -1, -1, nullptr, 0)) &lt; 0)
  
      {
  
          std::cerr &lt;&lt; "Failed to find video stream." &lt;&lt; std::endl;
  
          return nullptr;
  
      }
  
  
  
      auto codecContext = formatContext->streams[ret]->codec;
  
      auto codec = avcodec_find_decoder(codecContext->codec_id);
  
      if (!codec)
  
      {
  
          std::cerr &lt;&lt; "Failed to find codec." &lt;&lt; std::endl;
  
          return nullptr;
  
      }
  
  
  
      if ((ret = avcodec_open2(codecContext, codec, nullptr)) != 0)
  
      {
  
          std::cerr &lt;&lt; "Failed to open codec context." &lt;&lt; std::endl;
  
          return nullptr;
  
      }
  
  
  
      return codecContext;
  
  }
  
  
  
  // All the interesting bits are here
  
  int main(int argc, char* argv[])
  
  {
  
      auto path = "/path/to/test.png"; // Replace with valid path to PNG
  
      auto ret = 0;
  
  
  
      av_log_set_level(AV_LOG_DEBUG);
  
  
  
      av_register_all();
  
      avcodec_register_all();
  
  
  
      auto formatContext = avformat_alloc_context();
  
      if ((ret = avformat_open_input(&amp;formatContext, path, NULL, NULL)) != 0)
  
      {
  
          std::cerr &lt;&lt; "Failed to open input." &lt;&lt; std::endl;
  
          return -1;
  
      }
  
      av_dump_format(formatContext, 0, path, 0);
  
  
  
  //*/ Info is successfully found, but interferes with decoding
  
      if((ret = avformat_find_stream_info(formatContext, nullptr)) &lt; 0)
  
      {
  
          std::cerr &lt;&lt; "Failed to find stream info." &lt;&lt; std::endl;
  
          return -1;
  
      }
  
      av_dump_format(formatContext, 0, path, 0);
  
  //*/
  
  
  
      auto codecContext = open(AVMEDIA_TYPE_VIDEO, formatContext);
  
  
  
      AVPacket packet;
  
      av_init_packet(&amp;packet);
  
  
  
      if ((ret = av_read_frame(formatContext, &amp;packet)) &lt; 0)
  
      {
  
          std::cerr &lt;&lt; "Failed to read frame." &lt;&lt; std::endl;
  
          return -1;
  
      }
  
  
  
      auto frame = av_frame_alloc();
  
      auto decode_ok = 0;
  
      if ((ret = avcodec_decode_video2(codecContext, frame, &amp;decode_ok, &amp;packet)) &lt; 0 || !decode_ok)
  
      {
  
          std::cerr &lt;&lt; "Failed to decode frame." &lt;&lt; std::endl;
  
          return -1;
  
      }
  
  
  
      av_frame_free(&amp;frame);
  
      av_free_packet(&amp;packet);
  
  
  
      avcodec_close(codecContext);
  
  
  
      avformat_close_input(&amp;formatContext);
  
      av_free(formatContext);
  
  
  
      return 0;
  
  }
  
  </iostream>

  The format dump before avformat_find_stream_info prints :

  Input #0, image2, from '/path/to/test.png' :
    Duration : N/A, bitrate : N/A
      Stream #0:0, 0, 1/25 : Video : png, 25 tbn

  The format dump after avformat_find_stream_info prints :

  Input #0, image2, from '/path/to/test.png' :
    Duration : 00:00:00.04, start : 0.000000, bitrate : N/A
      Stream #0:0, 1, 1/25 : Video : png, rgba, 512x512 [SAR 3780:3780 DAR 1:1], 1/25, 25 tbr, 25 tbn, 25 tbc

  So it looks like the search yields potentially useful information. Can anybody shed some light on this problem ? Other image formats seem to work fine. I assume that this is a simple user error rather than a bug.

  Edit : Debug logging was already enabled, but the PNG decoder does not produce a lot of output. I have also tried setting a custom logging callback.

  Here is what I get without the call to avformat_find_stream_info, when decoding succeeds :

  Statistics : 52125 bytes read, 0 seeks

  And here is what I get with the call to avformat_find_stream_info, when decoding fails :

  Statistics : 52125 bytes read, 0 seeks
  detected 8 logical cores
  

  The image is 52125 bytes, so the whole file is read. I am not sure what the logical cores are referring to.

• ffmpeg conversion commandline needed [migrated]

  8 avril 2014, par user3506221

  I want to ask for help on converting a mpg videofile recorded from TV
  to a mp4 format my SAT Receiver can play, (mp4).
  Below are the format infos of source and target output by ffmpeg -i :
  All done on Linux.

  source :

  Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p(tv), 720x576 [SAR 64:45 DAR 16:9], max. 9500 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
  
  Stream #0:2[0x83]: Audio: ac3, 48000 Hz, stereo, fltp, 448 kb/s

  target :

  Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv), 720x406 [SAR 1:1 DAR 360:203], 1894 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default)
  
  Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 93 kb/s (default)

  ffmpeg -i ./source.mpg
  ffmpeg version 2.2 Copyright (c) 2000-2014 the FFmpeg developers
  built on Mar 24 2014 17:15:07 with gcc 4.8 (SUSE Linux)
  configuration : —shlibdir=/usr/lib —prefix=/usr —mandir=/usr/share/man —libdir=/usr/lib —enable-shared —disable-static —enable-debug —disable-stripping —extra-cflags='-fomit-frame-pointer -fmessage-length=0 -grecord-gcc-switches -fstack-protector -O2 -Wall -D_FORTIFY_SOURCE=2 -funwind-tables -fasynchronous-unwind-tables -g -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gsm' —enable-gpl —enable-x11grab —enable-version3 —enable-pthreads —enable-avfilter —enable-libpulse —enable-libvpx —enable-libopus —enable-libass —enable-libx265 —enable-libmp3lame —enable-libvorbis —enable-libtheora —enable-libspeex —enable-libxvid —enable-libx264 —enable-libschroedinger —enable-libgsm —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-postproc —enable-libdc1394 —enable-librtmp —enable-libfreetype —enable-avresample —enable-libtwolame —enable-libvo-aacenc —enable-gnutls
  libavutil 52. 66.100 / 52. 66.100
  libavcodec 55. 52.102 / 55. 52.102
  libavformat 55. 33.100 / 55. 33.100
  libavdevice 55. 10.100 / 55. 10.100
  libavfilter 4. 2.100 / 4. 2.100
  libavresample 1. 2. 0 / 1. 2. 0
  libswscale 2. 5.102 / 2. 5.102
  libswresample 0. 18.100 / 0. 18.100
  libpostproc 52. 3.100 / 52. 3.100
  [NULL @ 0x82baf20] start time is not set in estimate_timings_from_pts
  Input #0, mpeg, from './Rossini.mpg' :
  Duration : 01:49:08.19, start : 0.252622, bitrate : 4815 kb/s
  Stream #0:0[0x1bf] : Data : dvd_nav_packet
  Stream #0:1[0x1e0] : Video : mpeg2video (Main), yuv420p(tv), 720x576 [SAR 64:45 DAR 16:9], max. 9500 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
  Stream #0:2[0x83] : Audio : ac3, 48000 Hz, stereo, fltp, 448 kb/s
  At least one output file must be specified

  ffmpeg -i ./target.mp4
  ffmpeg version 2.2 Copyright (c) 2000-2014 the FFmpeg developers
  built on Mar 24 2014 17:15:07 with gcc 4.8 (SUSE Linux)
  configuration : —shlibdir=/usr/lib —prefix=/usr —mandir=/usr/share/man —libdir=/usr/lib —enable-shared —disable-static —enable-debug —disable-stripping —extra-cflags='-fomit-frame-pointer -fmessage-length=0 -grecord-gcc-switches -fstack-protector -O2 -Wall -D_FORTIFY_SOURCE=2 -funwind-tables -fasynchronous-unwind-tables -g -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gsm' —enable-gpl —enable-x11grab —enable-version3 —enable-pthreads —enable-avfilter —enable-libpulse —enable-libvpx —enable-libopus —enable-libass —enable-libx265 —enable-libmp3lame —enable-libvorbis —enable-libtheora —enable-libspeex —enable-libxvid —enable-libx264 —enable-libschroedinger —enable-libgsm —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-postproc —enable-libdc1394 —enable-librtmp —enable-libfreetype —enable-avresample —enable-libtwolame —enable-libvo-aacenc —enable-gnutls
  libavutil 52. 66.100 / 52. 66.100
  libavcodec 55. 52.102 / 55. 52.102
  libavformat 55. 33.100 / 55. 33.100
  libavdevice 55. 10.100 / 55. 10.100
  libavfilter 4. 2.100 / 4. 2.100
  libavresample 1. 2. 0 / 1. 2. 0
  libswscale 2. 5.102 / 2. 5.102
  libswresample 0. 18.100 / 0. 18.100
  libpostproc 52. 3.100 / 52. 3.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from './target.mp4' :
  Metadata :
  major_brand : mp42
  minor_version : 0
  compatible_brands : isommp42
  creation_time : 2014-03-31 22:03:51
  Duration : 01:20:35.84, start : 0.000000, bitrate : 1992 kb/s
  Stream #0:0(und) : Video : h264 (Main) (avc1 / 0x31637661), yuv420p(tv), 720x406 [SAR 1:1 DAR 360:203], 1894 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default)
  Metadata :
  creation_time : 2014-03-31 22:03:51
  handler_name : Mainconcept MP4 Video Media Handler
  Stream #0:1(und) : Audio : aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 93 kb/s (default)
  Metadata :
  creation_time : 2014-03-31 22:03:51
  handler_name : Mainconcept MP4 Sound Media Handler
  At least one output file must be specified

• Does ffmpeg version 0.7 support -codec copy option ? [migrated]

  2 avril 2014, par Boris Šuška

  I have to use ffmpeg version 0.7.15 to merge video (without audio) and audio file into one video file with audio. I would like to use command ffmpeg without re-encoding.

  I used this with newer version of ffmpeg command

  ffmpeg -y -i "video.mp4" -i "audio.mp4" -c:v copy -c:a copy -strict experimental -map 0:v:0 -map 1:a:0 "output.mp4"

  I need similar command for version 0.7.15, this is not working :

  ffmpeg -y -i "video.mp4" -i "audio.mp4" -vcodec copy -acodec copy -strict experimental -map 0:v:0 -map 1:a:0 "output.mp4"

  but this command works :

  ffmpeg -y -i "video.mp4" -i "audio.mp4" -vcodec libx264 -acodec aac -strict experimental -map 0:v:0 -map 1:a:0 "output.mp4"

  Does ffmpeg version 0.7.x support -vcodec copy and -acodec copy or something similar ? If no which first version supports this ?

  Update :
  -vcodec copy -acodec copy is not working for version 0.7.15 means if I have two files :

  -rwxrwxrwx 1 vagrant vagrant  2066268 Apr  1 11:41 audio.mp4
  
  -rwxrwxrwx 1 vagrant vagrant 33172453 Apr  1 11:41 video.mp4

  and I run ffmpeg command with -vcodec copy and -acodec copy options I get this output :

  ffmpeg version 0.7.15, Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Feb 22 2013 07:18:58 with gcc 4.4.5
  
    configuration: --enable-libdc1394 --prefix=/usr --extra-cflags='-Wall -g ' --cc='ccache cc' --enable-shared --enable-libmp3lame --enable-gpl --enable-libvorbis --enable-pthreads --enable-libfaac --enable-libxvid --enable-postproc --enable-x11grab --enable-libgsm --enable-libtheora --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libx264 --enable-libspeex --enable-nonfree --disable-stripping --enable-avfilter --enable-libdirac --disable-decoder=libdirac --enable-libfreetype --enable-libschroedinger --disable-encoder=libschroedinger --enable-version3 --enable-libopenjpeg --enable-libvpx --enable-librtmp --extra-libs=-lgcrypt --disable-altivec --disable-armv5te --disable-armv6 --disable-vis
  
    libavutil    50. 43. 0 / 50. 43. 0
  
    libavcodec   52.123. 0 / 52.123. 0
  
    libavformat  52.111. 0 / 52.111. 0
  
    libavdevice  52.  5. 0 / 52.  5. 0
  
    libavfilter   1. 80. 0 /  1. 80. 0
  
    libswscale    0. 14. 1 /  0. 14. 1
  
    libpostproc  51.  2. 0 / 51.  2. 0
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4':
  
    Metadata:
  
      major_brand     : dash
  
      minor_version   : 0
  
      compatible_brands: iso6avc1mp41
  
      creation_time   : 2014-01-01 01:05:45
  
    Duration: 00:04:19.92, start: 129.960000, bitrate: 1021 kb/s
  
      Stream #0.0(und): Video: h264 (High), yuv420p, 1920x1080, 25 tbr, 90k tbn, 50 tbc
  
      Metadata:
  
        creation_time   : 2014-01-01 01:05:45
  
  Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'audio.mp4':
  
    Metadata:
  
      major_brand     : dash
  
      minor_version   : 0
  
      compatible_brands: iso6mp41
  
      creation_time   : 2014-01-01 01:03:43
  
    Duration: 00:04:20.10, start: 130.054966, bitrate: 63 kb/s
  
      Stream #1.0(und): Audio: aac, 44100 Hz, stereo, s16
  
      Metadata:
  
        creation_time   : 2014-01-01 01:03:43
  
  Output #0, mp4, to 'output.mp4':
  
    Metadata:
  
      major_brand     : dash
  
      minor_version   : 0
  
      compatible_brands: iso6avc1mp41
  
      creation_time   : 2014-01-01 01:05:45
  
      encoder         : Lavf52.111.0
  
      Stream #0.0(und): Video: libx264, yuv420p, 1920x1080, q=2-31, 25 tbn, 25 tbc
  
      Metadata:
  
        creation_time   : 2014-01-01 01:05:45
  
      Stream #0.1(und): Audio: libfaac, 44100 Hz, stereo
  
      Metadata:
  
        creation_time   : 2014-01-01 01:03:43
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
    Stream #1.0 -> #0.1 [sync #0.0]
  
  Press [q] to stop, [?] for help
  
  frame=    0 fps=  0 q=-1.0 Lsize=    2038kB time=00:00:00.00 bitrate=   0.0kbits/s
  
  video:0kB audio:1994kB global headers:0kB muxing overhead 2.229202%

  and new output.mp4 file is tooo small and contains only audio :

  -rwxrwxrwx 1 vagrant vagrant  2066268 Apr  1 11:41 audio.mp4
  
  -rwxrwxrwx 1 vagrant vagrant  2087185 Apr  2 08:07 output.mp4
  
  -rwxrwxrwx 1 vagrant vagrant 33172453 Apr  1 11:41 video.mp4

  Output of newer version of ffmpeg (Windows version here) looks like this :

  ffmpeg version N-58288-g80e5859 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Nov 19 2013 18:06:56 with gcc 4.8.2 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --en
  
  able-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame -
  
  -enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  
    libavutil      52. 53.100 / 52. 53.100
  
    libavcodec     55. 43.101 / 55. 43.101
  
    libavformat    55. 21.100 / 55. 21.100
  
    libavdevice    55.  5.100 / 55.  5.100
  
    libavfilter     3. 91.100 /  3. 91.100
  
    libswscale      2.  5.101 /  2.  5.101
  
    libswresample   0. 17.104 /  0. 17.104
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4':
  
    Metadata:
  
      major_brand     : dash
  
      minor_version   : 0
  
      compatible_brands: iso6avc1mp41
  
      creation_time   : 2014-01-01 01:05:45
  
    Duration: 00:02:09.96, start: 0.000000, bitrate: 2042 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 2039 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc (default)
  
      Metadata:
  
        creation_time   : 2014-01-01 01:05:45
  
        handler_name    : VideoHandler
  
  Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'audio.mp4':
  
    Metadata:
  
      major_brand     : dash
  
      minor_version   : 0
  
      compatible_brands: iso6mp41
  
      creation_time   : 2014-01-01 01:03:43
  
    Duration: 00:02:10.05, start: 0.000000, bitrate: 127 kb/s
  
      Stream #1:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-01-01 01:03:43
  
        handler_name    : SoundHandler
  
  Output #0, mp4, to 'output.mp4':
  
    Metadata:
  
      major_brand     : dash
  
      minor_version   : 0
  
      compatible_brands: iso6avc1mp41
  
      encoder         : Lavf55.21.100
  
      Stream #0:0(und): Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 1920x1080, q=2-31, 2039 kb/s, 25 fps, 90k tbn, 90k tbc (default)
  
      Metadata:
  
        creation_time   : 2014-01-01 01:05:45
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac ([64][0][0][0] / 0x0040), 44100 Hz, stereo, 125 kb/s (default)
  
      Metadata:
  
        creation_time   : 2014-01-01 01:03:43
  
        handler_name    : SoundHandler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #1:0 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  frame= 3249 fps=0.0 q=-1.0 Lsize=   34438kB time=00:02:10.05 bitrate=2169.2kbits/s
  
  video:32354kB audio:1994kB subtitle:0 global headers:0kB muxing overhead 0.262659%

  and output.mp4 file size is higher than only video file and contains video and audio streams

  -rwxrwxrwx 1 vagrant vagrant  2066268 Apr  1 11:41 audio.mp4
  
  -rwxrwxrwx 1 vagrant vagrant 35264183 Apr  2 08:15 output.mp4
  
  -rwxrwxrwx 1 vagrant vagrant 33172453 Apr  1 11:41 video.mp4