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• avformat/mpegts : use buffer pools for allocating PES payloads

  3 avril 2020, par Marton Balint

  avformat/mpegts : use buffer pools for allocating PES payloads
  This brings a performance improvement when demuxing files, most of the
  
  improvement comes from buffer pooling unbound packets.
  time ffprobe -i samples/ffmpeg-bugs/trac/ticket6132/Samsung_HDR_-_Chasing_the_Light.ts -show_packets >/dev/null 2>&1
  Before :
  
      real    0m1.967s
  
      user    0m1.471s
  
      sys     0m0.493s
  After :
  
      real    0m1.497s
  
      user    0m1.364s
  
      sys     0m0.129s
  Based on a patch of James Almer.
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavformat/mpegts.c

• FFmpeg How to write video to a file

  9 décembre 2014, par NoviceAndNovice

  What i want is

   1. Get video packet from stream source
  
   2. Decode it
  
   3. And write  that decoded data as video file(avi, mpeg etc)

  I can able to get video Packets from a file (as AVPacket) and also can decode and save as an image.(raw)( FFmpeg tutorials show how to do it).
  But i can not ( do not know ) write that video data to a file(other) which can be played by media players(such as VLC).

  Best Wishes

  Ps : Real code samples will be great if possible...

  Now i make test with av_interleaved_write but i got strange error "non monotone timestamps" ( i have no control over pts values of media source )

  Some Extra Info

  In FFmpeg I have to

  1. Read media packets from media source ( it may be real file(.avi,mov) or even rtsp server).
  2. Then write those media packets to a real file (physical .avi, .mov etc file)

  I need reader and writer. I can read the media source file ( even encode packets according to given format). But i can not write to file...(which any player can play)

  And some pseudoCode

  File myFile("MyTestFile.avi");
  
  
  
  while ( source ->hasVideoPackets)
  
  {
  
       packet = source->GetNextVideoPacket();
  
       Frame decodedFrame = Decode(packet);
  
       VideoPacket encodedPacket = Encode( decodedFrame);
  
       myFile.WriteFile(encodedPacket);
  
   }

  Or Just write the original file without encode decode

       File myFile("MyTestFile.avi");
  
  
  
       while ( source ->hasVideoPackets)
  
       {
  
           packet = source->GetNextVideoPacket();
  
           myFile.WriteFile(packet);
  
       }

  Then

  I can able to open MyTest.avi file with a player.

• Get the actual duration of a sound file in C++ (libavformat)

  1er avril 2017, par user3734670

  I want to get the duration of a sound file in my C++ application. I want to support a lot of sound codecs, so I decided to use libavformat.

  I get the duration, but I get also a notification that the duration can be inaccurate. In another Stackoverflow question (How to get the real, actual duration of an MP3 file (VBR or CBR) server-side) it was mentioned that you can decode the file completely to get the actual duration. How can I this archive with libavformat ?

  My code to get the inaccurate duration :

  av_register_all();
  
  AVFormatContext* pFormatCtx = avformat_alloc_context();
  
  avformat_open_input(&pFormatCtx, audio_file, NULL, NULL);
  
  avformat_find_stream_info(pFormatCtx, 0);
  
  av_dump_format(pFormatCtx, 0, audio_file, 0);
  
  int64_t duration = pFormatCtx->duration;
  
  std::cout << ceil((double) duration / AV_TIME_BASE) << std::endl;
  
  avformat_close_input(&pFormatCtx);
  
  avformat_free_context(pFormatCtx);