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• Libav Transcoding to H264 : Frames being dropped

  21 juin 2014, par roman

  I’m sorry if my question isn’t too well formulated, I’m only now getting started with FFmpeg and Libav. I’m not too knowledgable about media formats either, I pretty much learned all I know about the topic this past month. I’ve been doing as much research as I can, and have gotten pretty far, but I’ve only now gotten to the point where I’m almost unsure what my question actually is ! These are more like observations, but hopefully some of the experts can help me out here.

  I’m trying to transcode Gifs into MP4s using FFmpeg’s libraries, but I’m running into a strange issue when using the H264 Codec. In my transcoding loop, I keep a count of the number of frames that I write out (by verifying the return value of av_write_frame). In a particular sample, I count a total of 166 frames written out. If I examine FFmpeg’s converted file using FFprobe (the functionality I’m wanting to emulate using my program, a conversion from Gif to MP4), FFmpeg’s output file also seems to have 166 frames, but when I examine my output with FFprobe, I seem to only have 144 frames. What I find a bit interesting is that if I simply change my codec from H264 to MPEG4, my output appears to have the 166 frames, matching FFmpeg’s output and my counter. I get very similar results with different Gif files, where my counter of frames written matches FFmpeg’s output’s frame count, but my output seems to drop some frames.

  Encoder settings :

  ostream_codec_context->codec_id = CODEC_IN_USE;  //CODEC_ID_H264 or CODEC_ID_MPEG4
  
  ostream_codec_context->pix_fmt = AV_PIX_FMT_YUV420P;
  
  ostream_codec_context->codec_type = AVMEDIA_TYPE_VIDEO;
  
  ostream_codec_context->flags = CODEC_FLAG_GLOBAL_HEADER;
  
  ostream_codec_context->profile = FF_PROFILE_MPEG4_SIMPLE;
  
  
  
  ostream_codec_context->gop_size = istream_codec_context->gop_size;
  
  ostream_codec_context->time_base = istream_codec_context->time_base;
  
  
  
  ostream_codec_context->width  = (istream_codec_context->width  / 2) * 2;
  
  ostream_codec_context->height = (istream_codec_context->height / 2) * 2;    

  Transcoding loop :

  I’ve omitted some error-checking code and debugging statements

  avformat_write_header(oformat_context, NULL);
  
  while (av_read_frame(iformat_context, &packet) == 0 ) 
  
  {
  
     if (packet.stream_index == istream_index) 
  
     {   
  
        avcodec_decode_video2(istream_codec_context, ipicture, &full_frame, &packet);
  
        if (full_frame) 
  
        {
  
           sws_scale(image_conversion_context, 
  
                     (uint8_t const * const *) ipicture->data,
  
                     ipicture->linesize, 0, istream_codec_context->height,
  
                     opicture->data, opicture->linesize);
  
  
  
           opicture->pts = av_rescale_q(packet.pts, istream_codec_context->time_base,
  
                                        ostream->time_base);
  
  
  
           ret = avcodec_encode_video2(ostream_codec_context, &packet, 
  
                                       opicture, &got_packet);
  
           if (!ret)
  
           {
  
              ret = av_write_frame(oformat_context, &packet);
  
              if (ret < 0)
  
                 num_frames_written++;
  
           }
  
        }
  
     }
  
     av_free_packet(&packet);
  
     av_init_packet(&packet);
  
  }

  I’m also having issues with my output’s bit-rate. I can try setting it with the rest of my encoder settings, but the bit-rate that FFprobe shows is not the same as what I give the codec context. I tried setting the bit-rate to constant values just to see how it affected my output, and although my output’s bit-rate isn’t the same as what I give it, I found that my input definitely seems to influence the output’s actual bit-rate. I found a post that seems to be dealing with my issue, but the solution listed there does not seem to fix my issue.

  http://ffmpeg.org/pipermail/libav-user/2012-July/002492.html

  Another thing worth mentioning is that my various time bases don’t seem to match up with those of FFmpeg’s output. Notably, my output’s TBC seems to be twice the inverse of my output codec context’s time base. I’m not too sure if this is an issue with the Gif file format, my output codec context’s always seems to be set to 1/100.

  Bit-rate calculation and setting

  int calculated_br = istream_codec_context->time_base.den *     
  
                      avpicture_get_size(AV_PIX_FMT_YUV420P, ostream_codec_context->width, 
  
                                         ostream_codec_context->height);    
  
  
  
  ostream_codec_context->bit_rate = calculated_br;
  
  ostream_codec_context->rc_min_rate = calculated_br;
  
  ostream_codec_context->rc_max_rate = calculated_br;
  
  ostream_codec_context->rc_buffer_size = calculated_br;

  I’ve got a hunch that all these issues could be related to me not setting my PTS/DTS correctly, even though my output’s pts/dts values match those of FFmpeg’s output.

  I would appreciate some help,
  Thank you !

• Revision cdc954fdc8 : skip the un-necessary motion search in the first pass This patch allows the VP9

  16 juin 2014, par Pengchong Jin

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
  
  skip the un-necessary motion search in the first pass

  This patch allows the VP9 encoder to skip the un-necessary
  motion search in the first pass. It computes the motion error
  of 0,0 motion using the last source frame as the reference,
  and skips the further motion search if this error is small.

  Borg test shows overall the patch gives PSNR gain (derf -0.001%,
  yt 0.341%, hd 0.282%). Individual clips may have PSNR gain or
  loss. The best PSNR performance is 7.347% and the worst is -0.662%.
  The first pass encoding speedup for slideshow clips is over 30%.

  Change-Id : I4cac4dbd911f277ee858e161f3ca652c771344fe

• pip install av produces a LINK 1181 error

  6 février 2020, par user8606643

  initially, pip install av asked me to download visual C++ 14 build tools which I did
  but it is still showing me LINK 1181 errors

  I need this pyAV pakcage which is obtained by pip install av for a project, but it always shows some kind of error linked with C++ and i also have ffmpeg installed.

  C:\Users\manop>pip install av
  
  Collecting av
  
    Using cached av-7.0.0.tar.gz (2.3 MB)
  
  Building wheels for collected packages: av
  
    Building wheel for av (setup.py) ... error
  
    ERROR: Command errored out with exit status 1:
  
     command: 'c:\users\manop\appdata\local\programs\python\python37\python.exe' -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'C:\\Users\\manop\\AppData\\Local\\Temp\\pip-install-rydo0uqj\\av\\setup.py'"'"'; __file__='"'"'C:\\Users\\manop\\AppData\\Local\\Temp\\pip-install-rydo0uqj\\av\\setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' bdist_wheel -d 'C:\Users\manop\AppData\Local\Temp\pip-wheel-oti9y28m'
  
         cwd: C:\Users\manop\AppData\Local\Temp\pip-install-rydo0uqj\av\
  
    Complete output (38 lines):
  
    running bdist_wheel
  
    running build
  
    running build_py
  
    creating build
  
    creating build\lib.win-amd64-3.7
  
    creating build\lib.win-amd64-3.7\av
  
    copying av\datasets.py -> build\lib.win-amd64-3.7\av
  
    copying av\deprecation.py -> build\lib.win-amd64-3.7\av
  
    copying av\__init__.py -> build\lib.win-amd64-3.7\av
  
    copying av\__main__.py -> build\lib.win-amd64-3.7\av
  
    creating build\lib.win-amd64-3.7\av\audio
  
    copying av\audio\__init__.py -> build\lib.win-amd64-3.7\av\audio
  
    creating build\lib.win-amd64-3.7\av\codec
  
    copying av\codec\__init__.py -> build\lib.win-amd64-3.7\av\codec
  
    creating build\lib.win-amd64-3.7\av\container
  
    copying av\container\__init__.py -> build\lib.win-amd64-3.7\av\container
  
    creating build\lib.win-amd64-3.7\av\data
  
    copying av\data\__init__.py -> build\lib.win-amd64-3.7\av\data
  
    creating build\lib.win-amd64-3.7\av\filter
  
    copying av\filter\__init__.py -> build\lib.win-amd64-3.7\av\filter
  
    creating build\lib.win-amd64-3.7\av\sidedata
  
    copying av\sidedata\__init__.py -> build\lib.win-amd64-3.7\av\sidedata
  
    creating build\lib.win-amd64-3.7\av\subtitles
  
    copying av\subtitles\__init__.py -> build\lib.win-amd64-3.7\av\subtitles
  
    creating build\lib.win-amd64-3.7\av\video
  
    copying av\video\__init__.py -> build\lib.win-amd64-3.7\av\video
  
    running build_ext
  
    running config
  
    writing build\temp.win-amd64-3.7\Release\include\pyav\config.h
  
    running cythonize
  
    building 'av.buffer' extension
  
    creating build\temp.win-amd64-3.7\Release\src
  
    creating build\temp.win-amd64-3.7\Release\src\av
  
    C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.16.27023\bin\HostX64\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -Ic:\users\manop\appdata\local\programs\python\python37\include -Ibuild\temp.win-amd64-3.7\Release\include -Iinclude -Ic:\users\manop\appdata\local\programs\python\python37\include -Ic:\users\manop\appdata\local\programs\python\python37\include -Ibuild\temp.win-amd64-3.7\Release\include "-IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.16.27023\Include" "-IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\shared" "-IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\um" "-IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\winrt" "-IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\ucrt" /Tcsrc\av\buffer.c /Fobuild\temp.win-amd64-3.7\Release\src\av\buffer.obj
  
    buffer.c
  
    C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.16.27023\bin\HostX64\x64\link.exe /nologo /INCREMENTAL:NO /LTCG /DLL /MANIFEST:EMBED,ID=2 /MANIFESTUAC:NO /LIBPATH:c:\users\manop\appdata\local\programs\python\python37\PCbuild\amd64 /LIBPATH:c:\users\manop\appdata\local\programs\python\python37\libs /LIBPATH:c:\users\manop\appdata\local\programs\python\python37\libs /LIBPATH:c:\users\manop\appdata\local\programs\python\python37\PCbuild\amd64 "/LIBPATH:C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.16.27023\Lib\x64" "/LIBPATH:C:\Program Files (x86)\Windows Kits\10\lib\10.0.18362.0\um\x64" /LIBPATH:C:\WINDOWS\Microsoft.NET\Framework64\v4.0.30319 "/LIBPATH:C:\Program Files (x86)\Windows Kits\10\lib\10.0.18362.0\ucrt\x64" swresample.lib swscale.lib avdevice.lib avutil.lib avcodec.lib avformat.lib avfilter.lib /EXPORT:PyInit_buffer build\temp.win-amd64-3.7\Release\src\av\buffer.obj /OUT:build\lib.win-amd64-3.7\av\buffer.cp37-win_amd64.pyd /IMPLIB:build\temp.win-amd64-3.7\Release\src\av\buffer.cp37-win_amd64.lib /OPT:NOREF
  
    LINK : fatal error LNK1181: cannot open input file 'swresample.lib'
  
    error: command 'C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Community\\VC\\Tools\\MSVC\\14.16.27023\\bin\\HostX64\\x64\\link.exe' failed with exit status 1181
  
    ----------------------------------------
  
    ERROR: Failed building wheel for av
  
    Running setup.py clean for av
  
  Failed to build av
  
  Installing collected packages: av
  
      Running setup.py install for av ... error
  
      ERROR: Command errored out with exit status 1:
  
       command: 'c:\users\manop\appdata\local\programs\python\python37\python.exe' -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'C:\\Users\\manop\\AppData\\Local\\Temp\\pip-install-rydo0uqj\\av\\setup.py'"'"'; __file__='"'"'C:\\Users\\manop\\AppData\\Local\\Temp\\pip-install-rydo0uqj\\av\\setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' install --record 'C:\Users\manop\AppData\Local\Temp\pip-record-xac0xiy4\install-record.txt' --single-version-externally-managed --compile --install-headers 'c:\users\manop\appdata\local\programs\python\python37\Include\av'
  
           cwd: C:\Users\manop\AppData\Local\Temp\pip-install-rydo0uqj\av\
  
      Complete output (38 lines):
  
      running install
  
      running build
  
      running build_py
  
      creating build
  
      creating build\lib.win-amd64-3.7
  
      creating build\lib.win-amd64-3.7\av
  
      copying av\datasets.py -> build\lib.win-amd64-3.7\av
  
      copying av\deprecation.py -> build\lib.win-amd64-3.7\av
  
      copying av\__init__.py -> build\lib.win-amd64-3.7\av
  
      copying av\__main__.py -> build\lib.win-amd64-3.7\av
  
      creating build\lib.win-amd64-3.7\av\audio
  
      copying av\audio\__init__.py -> build\lib.win-amd64-3.7\av\audio
  
      creating build\lib.win-amd64-3.7\av\codec
  
      copying av\codec\__init__.py -> build\lib.win-amd64-3.7\av\codec
  
      creating build\lib.win-amd64-3.7\av\container
  
      copying av\container\__init__.py -> build\lib.win-amd64-3.7\av\container
  
      creating build\lib.win-amd64-3.7\av\data
  
      copying av\data\__init__.py -> build\lib.win-amd64-3.7\av\data
  
      creating build\lib.win-amd64-3.7\av\filter
  
      copying av\filter\__init__.py -> build\lib.win-amd64-3.7\av\filter
  
      creating build\lib.win-amd64-3.7\av\sidedata
  
      copying av\sidedata\__init__.py -> build\lib.win-amd64-3.7\av\sidedata
  
      creating build\lib.win-amd64-3.7\av\subtitles
  
      copying av\subtitles\__init__.py -> build\lib.win-amd64-3.7\av\subtitles
  
      creating build\lib.win-amd64-3.7\av\video
  
      copying av\video\__init__.py -> build\lib.win-amd64-3.7\av\video
  
      running build_ext
  
      running config
  
      writing build\temp.win-amd64-3.7\Release\include\pyav\config.h
  
      running cythonize
  
      building 'av.buffer' extension
  
      creating build\temp.win-amd64-3.7\Release\src
  
      creating build\temp.win-amd64-3.7\Release\src\av
  
      C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.16.27023\bin\HostX64\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -Ibuild\temp.win-amd64-3.7\Release\include -Iinclude -Ic:\users\manop\appdata\local\programs\python\python37\include -Ic:\users\manop\appdata\local\programs\python\python37\include -Ic:\users\manop\appdata\local\programs\python\python37\include -Ibuild\temp.win-amd64-3.7\Release\include "-IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.16.27023\Include" "-IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\shared" "-IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\um" "-IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\winrt" "-IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\ucrt" /Tcsrc\av\buffer.c /Fobuild\temp.win-amd64-3.7\Release\src\av\buffer.obj
  
      buffer.c
  
      C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.16.27023\bin\HostX64\x64\link.exe /nologo /INCREMENTAL:NO /LTCG /DLL /MANIFEST:EMBED,ID=2 /MANIFESTUAC:NO /LIBPATH:c:\users\manop\appdata\local\programs\python\python37\PCbuild\amd64 /LIBPATH:c:\users\manop\appdata\local\programs\python\python37\libs /LIBPATH:c:\users\manop\appdata\local\programs\python\python37\libs /LIBPATH:c:\users\manop\appdata\local\programs\python\python37\PCbuild\amd64 "/LIBPATH:C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.16.27023\Lib\x64" "/LIBPATH:C:\Program Files (x86)\Windows Kits\10\lib\10.0.18362.0\um\x64" /LIBPATH:C:\WINDOWS\Microsoft.NET\Framework64\v4.0.30319 "/LIBPATH:C:\Program Files (x86)\Windows Kits\10\lib\10.0.18362.0\ucrt\x64" avutil.lib avfilter.lib swresample.lib swscale.lib avformat.lib avcodec.lib avdevice.lib /EXPORT:PyInit_buffer build\temp.win-amd64-3.7\Release\src\av\buffer.obj /OUT:build\lib.win-amd64-3.7\av\buffer.cp37-win_amd64.pyd /IMPLIB:build\temp.win-amd64-3.7\Release\src\av\buffer.cp37-win_amd64.lib /OPT:NOREF
  
      LINK : fatal error LNK1181: cannot open input file 'avutil.lib'
  
      error: command 'C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Community\\VC\\Tools\\MSVC\\14.16.27023\\bin\\HostX64\\x64\\link.exe' failed with exit status 1181
  
      ----------------------------------------
  
  ERROR: Command errored out with exit status 1: 'c:\users\manop\appdata\local\programs\python\python37\python.exe' -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'C:\\Users\\manop\\AppData\\Local\\Temp\\pip-install-rydo0uqj\\av\\setup.py'"'"'; __file__='"'"'C:\\Users\\manop\\AppData\\Local\\Temp\\pip-install-rydo0uqj\\av\\setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' install --record 'C:\Users\manop\AppData\Local\Temp\pip-record-xac0xiy4\install-record.txt' --single-version-externally-managed --compile --install-headers 'c:\users\manop\appdata\local\programs\python\python37\Include\av' Check the logs for full command output.

  These are my visual C++ selections :
  my visual studio installer individual components selection