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• Synchronizing FFMPEG video frames using PTS

  10 août 2015, par DundeeDave

  I’m attempting to synchronize the frames decoded from an MP4 video. I’m using the FFMPEG libraries. I’ve decoded and stored each frame and successfully displayed the video over an OPENGL plane.

  I’ve started a timer just before cycling through the frames ; the aim being to synchronize the Video correctly. I then compare the PTS of each frame against this timer. I stored the PTS received from the packet during decoding.

  What is displayed within my application does not seem to play at the rate I expect. It plays faster than the original video file would within a media player.

  I am inexperienced with FFMPEG and programming video in general. Am I tackling this the wrong way ?

  Here is an example of what I’m attempting to do

              FrameObject frameObject = frameQueue.front();
  
  
  
              AVFrame frame = *frameObject.pFrame;
  
  
  
              videoClock += dt;
  
  
  
              if(videoClock >= globalPTS)
  
              {
  
                  //Draw the Frame to a texture
  
                  DrawFrame(&frame, frameObject.m_pts);
  
  
  
                  frameQueue.pop_front();
  
  
  
                  globalPTS = frameObject.m_pts;
  
              }

  Please note I’m using C++, Windows, Opengl, FFMPEG and the VS2010 IDE

• Invalid pixel aspect ratio in ffmpeg

  26 septembre 2014, par dudeofea

  I want to scale a video to a certain size using ffmpeg, but I get the following error :

  ffmpeg -i Ad_939.avi -vf scale=1000:64 test_ad.avi       
  
  ffmpeg version 2.3.3 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Sep 26 2014 10:31:06 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  
    configuration: 
  
    libavutil      52. 92.100 / 52. 92.100
  
    libavcodec     55. 69.100 / 55. 69.100
  
    libavformat    55. 48.100 / 55. 48.100
  
    libavdevice    55. 13.102 / 55. 13.102
  
    libavfilter     4. 11.100 /  4. 11.100
  
    libswscale      2.  6.100 /  2.  6.100
  
    libswresample   0. 19.100 /  0. 19.100
  
  Input #0, avi, from 'Ad_939.avi':
  
    Metadata:
  
      encoder         : Lavf56.4.101
  
    Duration: 00:00:20.50, start: 0.000000, bitrate: 75 kb/s
  
      Stream #0:0: Video: wmv2 (WMV2 / 0x32564D57), yuv420p, 160x64, 68 kb/s, SAR 32:45 DAR 16:9, 24 fps, 24 tbr, 24 tbn, 24 tbc
  
  [mpeg4 @ 0x2305cc0] Invalid pixel aspect ratio 128/1125, limit is 255/255 reducing
  
  [mpeg4 @ 0x2305cc0] too many threads/slices (5), reducing to 4
  
  Output #0, avi, to 'test_ad.avi':
  
    Metadata:
  
      ISFT            : Lavf55.48.100
  
      Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 1000x64 [SAR 19:167 DAR 2375:1336], q=2-31, 200 kb/s, SAR 128:1125 DAR 16:9, 24 fps, 24 tbn, 24 tbc
  
      Metadata:
  
        encoder         : Lavc55.69.100 mpeg4
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (wmv2 (native) -> mpeg4 (native))
  
  Press [q] to stop, [?] for help
  
  frame=  228 fps=0.0 q=2.0 size=     222kB time=00:00:09.50 bitrate= 191.6kbits/s
  
  frame=  468 fps=467 q=2.0 size=     435kB time=00:00:19.50 bitrate= 182.8kbits/s
  
  frame=  492 fps=456 q=2.0 Lsize=     458kB time=00:00:20.50 bitrate= 183.1kbits/s    
  
  video:441kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 3.981523%

  I’ve read around and it seems this was a past bug but that was 3 years ago. I’ve tried running this command with version 2.4.1, 2.3.3, 2.4.git (compiled from source Sept 16, 2014), and N-40951-g1ea7a3e (Newest static build) and they all fail.

  EDIT : When I say fail I mean that the video is not playing at the proper resolution. The file’s properties say that it is 1000x64 but VLC plays (as well as my website using a <video></video> tag) it with the original aspect ratio with the new width which is not what I want. I want a crunched up video the same size no matter what.

  Is there something I’m missing ?

• Merge commit ’9a03c2323593173a201cb75edd1b49887cf811ed’

  7 octobre 2014, par Michael Niedermayer

  Merge commit ’9a03c2323593173a201cb75edd1b49887cf811ed’
  * commit ’9a03c2323593173a201cb75edd1b49887cf811ed’ :
  
    h263dec : Force padding bug workaround for H.263.
  This is not merged as it breaks a good part of the error concealment/resilience for H.263
  
  Also, messenger.h263 plays fine in ffmpeg.
  
  If anyone has any other h263 files that do not work, please open an issue on trak or
  
  mail me !
  See : d225b0f7aaa65eafccc87165130e1c4bab71708b
  
  Merged-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/h263dec.c