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• Decoded H.264 gives different frame and context size

  28 août 2015, par Deanna

  We’re using avcodec to decode H.264, and in some circumstances, after changing the resolution, avcodec gets confused, and gives two different sizes for the decoded frame :

  if (av_init_packet_dll)
  
      av_init_packet_dll(&avpkt);
  
  
  
  avpkt.data  = pBuffer;
  
  avpkt.size  = lBuffer;
  
  
  
  //  Make sure the output frame has NULLs for the data lines
  
  pAVFrame->data[0]   = NULL;
  
  pAVFrame->data[1]   = NULL;
  
  pAVFrame->data[2]   = NULL;
  
  pAVFrame->data[3]   = NULL;
  
  
  
  res = avcodec_decode_video2_dll(pCodecCtx, pAVFrame, &FrameFinished, &avpkt);
  
  
  
  DEBUG_LOG("Decoded frame: %d, %d, resulting dimensions: context: %dx%d, frame: %dx%d\n", res, FrameFinished, pCodecCtx->width, pCodecCtx->height, pAVFrame->width, pAVFrame->height);
  
  
  
  if (pCodecCtx->width != pAVFrame->width || pCodecCtx->height != pAVFrame->height) {
  
      OutputDebugStringA("Size mismatch, ignoring frame!\n");
  
      FrameFinished = 0;
  
  }
  
  
  
  if (FrameFinished == 0)
  
      OutputDebugStringA("Unfinished frame\n");

  This results in this log (with some surrounding lines) :

  [5392] Decoded frame: 18690, 1, resulting dimensions: context: 640x480, frame: 640x480
  
  [5392] Set dimensions to 640x480 in DecodeFromMap
  
  [5392] checking size 640x480 against 640x480
  
  [5392] Drawing 640x480, 640x480, 640x480, 0x05DB0060, 0x05DFB5C0, 0x05E0E360, 0x280, to surface 0x03198100, 1280x800
  
  [5392] Drawing 640x480, 640x480, 640x480, 0x05DB0060, 0x05DFB5C0, 0x05E0E360, 0x280, to surface 0x03198100, 1280x800
  
  [5392] Delayed frames seen. Reenabling low delay requires a codec flush.
  
  [5392] Reinit context to 1280x800, pix_fmt: yuvj420p
  
  *[5392] Decoded frame: 54363, 1, resulting dimensions: context: 1280x800, frame: 640x480
  
  [5392] Set dimensions to 1280x800 in DecodeFromMap
  
  [5392] checking size 1280x800 against 640x480
  
  [5392] Found adapter NVIDIA GeForce GTX 650 ({D7B71E3E-4C86-11CF-4E68-7E291CC2C435}) on monitor 00020003
  
  [5392] Found adapter NVIDIA GeForce GTX 650 ({D7B71E3E-4C86-11CF-4E68-7E291CC2C435}) on monitor FA650589
  
  [5392] Creating Direct3D interface on adapter 1 at 1280x800 window 0015050C
  
  [5392] Direct3D created using hardware vertex processing on HAL.
  
  [5392] Creating D3D surface of 1280x800
  
  [5392] Result 0x00000000, got surface 0x03210C40
  
  [5392] Drawing 1280x800, 1280x800, 640x480, 0x02E3B0A0, 0x02E86600, 0x02E993A0, 0x280, to surface 0x03210C40, 1280x800

  The line where this breaks is marked with a *. pAVFrame contains the old frame dimensions, while pCodecCtx contains the new dimensions. When the drawing code than tries to access the data as a 1280x800 image, it hits an access violation.

  When going down a size, avcodec transitions correctly, and sets FrameFinished to 0 and leaves pAVFrame resolution at 0x0.

  Can anyone think what is causing this, why avcodec is reporting success, yet not doing anything, and what I can do to correctly resolve this ?

  For now, the mismatch check is protecting against this.

  The avcodec in use is built from git-5cba529 by Zeranoe.

  FFmpeg version: 2015-03-31 git-5cba529
  
    libavutil      54. 21.100 / 54. 21.100
  
    libavcodec     56. 32.100 / 56. 32.100

• RTMPE FFMPEG on Linux [on hold]

  31 août 2015, par user3317118

  I’m getting download on Windows but on Linux can not, gives this error.
  [![enter image description here][1]][1]

  bebetoalves: ~/Web $ ffmpeg -f concat -i ep.txt -codec copy theroyalrangers.mkv  

  ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration : —disable-yasm

  libavutil 54. 27.100 / 54. 27.100
  libavcodec 56. 41.100 / 56. 41.100
  libavformat 56. 36.100 / 56. 36.100
  libavdevice 56. 4.100 / 56. 4.100
  libavfilter 5. 16.101 / 5. 16.101
  libswscale 3. 1.101 / 3. 1.101
  libswresample 1. 2.100 / 1. 2.100

  [concat @ 0x1bf4260] Impossible to open ’rtmpe ://viacomnickstrmfs.fplive.net/viacomnickstrm/gsp.alias/me
  diabus/kids.com/2015/08/26/11/22/23884690/HDXPR510A1_884690_5801915_1280x720_3500_h32.mp4’

  ep.txt : Protocol not found
  bebetoalves : /Web $

• Getting video sped-up with FFmpeg to have the correct duration

  1er septembre 2015, par Vincent Tjeng

  I’ve been speeding up video using ffmpeg by following these instructions. For example, to speed up the video by 4 times, I run the following command :

  ffmpeg -i vid.MP4 -filter:v "setpts=0.25*PTS" vid_fast.MP4

  While the video is sped up by the indicated amount, the duration of the video (as indicated under its properties, and also when I play the video in VLC) remains the same as the original. For example, if vid.MP4 is initially 4 minutes, then vid_fast.MP4 is also 4 minutes, rather than being 1 minute long as expected. (The additional 3 minutes just consist of the video being frozen on the last frame.)

  This is a bit of a hassle, since I need to delete the additional 3 minutes that I’m not interested in. Is there any way to avoid this ?

  Here is a bit more information on the version of ffmpeg I’m using :

  ffmpeg version N-69060-gcd960c8 Copyright (c) 2000-2015 the FFmpeg developers
  
    built on Jan 14 2015 22:13:45 with gcc 4.9.2 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
  
  enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-lib
  
  modplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrw
  
  b --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinge
  
  r --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --en
  
  able-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis
  
   --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-
  
  libx265 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enab
  
  le-zlib
  
    libavutil      54. 16.100 / 54. 16.100
  
    libavcodec     56. 20.100 / 56. 20.100
  
    libavformat    56. 18.101 / 56. 18.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5.  7.101 /  5.  7.101
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Hyper fast Audio and Video encoder