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• Fastest way to create a multi-page tiff

  26 octobre 2012, par user1414470

  I need to create a multi-frame tiff file to store large number of images. Time consumption is very important here. Also my initial format is an 'avi' video so if i can change it directly it'd be great. Can you tell me how to do that ? weather it is through programming or using some software isn't important but it would be great if it were through just ffmpeg(I'm already doing the frame separation with ffmpeg).

  Thank you

• 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

• Use Windows ffmpeg to record audio output without using the StereoMix

  5 janvier 2019, par DevtelSoftware

  I am looking for a way to record the audio output (speakers) using Windows ffmpeg.
  I need to do this WITHOUT installing any extra dshow filters and without having the StereoMix input enabled (since this is not available on many computers).

  I have read in the ffmpeg documentation that the -map would allow redirecting an audio output so that ffmpeg sees it as an audio input but I can’t find any example of how to do that.

  In Linux I managed to do it like this :

  ffmpeg -f pulse -ac 2 -ar 44100 -i alsa_output.pci-0000_00_1f.4.analog-stereo.monitor -f pulse -ac 2 -ar 44100 -i alsa_input.pci-0000_00_1f.4.analog-stereo -filter_complex amix=inputs=2 test.mp4

  However I can’t find a similar way to do it in Windows and MacOSX.

  So in short, is it possible with the Windows ffmpeg to record audio from the speakers without extra dshow filters (out-of-the-box) ? Same question goes for MacOSX.

  Thanks !