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• lavc/rawdec : Use AV_PIX_FMT_PAL8 for raw 1 bpp video in AVI

  28 janvier 2016, par Mats Peterson

  lavc/rawdec : Use AV_PIX_FMT_PAL8 for raw 1 bpp video in AVI
   From
  
  https://msdn.microsoft.com/en-us/library/windows/desktop/dd318229%28v=vs.85%29.aspx:
  "If biCompression equals BI_RGB and the bitmap uses 8 bpp or less, the
  
  bitmap has a color table immediatelly following the BITMAPINFOHEADER
  
  structure. The color table consists of an array of RGBQUAD values. The
  
  size of the array is given by the biClrUsed member. If biClrUsed is
  
  zero, the array contains the maximum number of colors for the given
  
  bitdepth ; that is, 2^biBitCount colors."
  Nothing about "monochrome" here. Unfortunately, pal8 to monow conversion
  
  seems a bit flaky, but that’s another story.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/raw.c
  • [DH] tests/ref/vsynth/vsynth1-bpp1
  • [DH] tests/ref/vsynth/vsynth2-bpp1
  • [DH] tests/ref/vsynth/vsynth3-bpp1
  • [DH] tests/ref/vsynth/vsynth_lena-bpp1

• riffdec : Explicitly null-terminate array to work around VC++ bug

  28 janvier 2016, par Bruce Dawson

  riffdec : Explicitly null-terminate array to work around VC++ bug
  Due to this bug in VC++ 2015 Update 1 :
  
  https://connect.microsoft.com/VisualStudio/feedback/details/2291638
  the ’key’ array in ff_read_riff_info() ends up being not null
  
  terminated which led to failures in a Chromium unit tests. Update 2
  
  should have a fix, but until then it is important to avoid problems.
  

  • [DH] libavformat/riffdec.c

• Failed to execute : 0x80070057, when decoding video via ffmpeg with dxva2

  18 avril 2016, par CD83

  I have successfully implemented a video player using ffmpeg. I am now trying to use hardware decoding but I’m facing a couple issues.
  I found a post that I followed as a starting point here : http://comments.gmane.org/gmane.comp.video.ffmpeg.libav.user/13523

  I have updated the code that setup the necessary stuff for the decoder. The updated code is available here : https://drive.google.com/file/d/0B5ufHdoDzA4ieVk5UVpxcDNzRHc/view?usp=sharing

  And this is how I’m using it to initialize the decoder :

  // Prepare the decoding context
  
  AVCodec *codec = nullptr;
  
  _codecContext = _avFormatContext->streams[_streamIndex]->codec;
  
  if ((codec = avcodec_find_decoder(_codecContext->codec_id)) == 0)
  
  {
  
      std::cout << "Unsupported video codec!" << std::endl;
  
      return false;
  
  }
  
  
  
  _codecContext->thread_count = 1;  // Multithreading is apparently not compatible with hardware decoding
  
  InputStream *ist = new InputStream();
  
  ist->hwaccel_id = HWACCEL_AUTO;
  
  ist->hwaccel_device = "dxva2";
  
  ist->dec = codec;
  
  ist->dec_ctx = _codecContext;
  
  _codecContext->coded_width = _width;
  
  _codecContext->coded_height = _height;
  
  
  
  _codecContext->opaque = ist;
  
  dxva2_init(_codecContext);
  
  
  
  _codecContext->get_buffer2 = ist->hwaccel_get_buffer;
  
  _codecContext->get_format = GetHwFormat;
  
  _codecContext->thread_safe_callbacks = 1;
  
  
  
  if (avcodec_open2(_codecContext, codec, nullptr) < 0)
  
  {
  
      std::cout << "Video codec open error" << std::endl;
  
      return false;
  
  }

  And here is the definition of GetHwFormat referenced above :

  AVPixelFormat GetHwFormat(AVCodecContext *s, const AVPixelFormat *pix_fmts)
  
  {
  
      InputStream* ist = (InputStream*)s->opaque;
  
      ist->active_hwaccel_id = HWACCEL_DXVA2;
  
      ist->hwaccel_pix_fmt = AV_PIX_FMT_DXVA2_VLD;
  
      return ist->hwaccel_pix_fmt;
  
  }

  When I open an mp4 (encoded in h264) video that is HD resolution or less, everything seems to be working fine. However, as soon as I try higher resolution videos like 3840x2160, I get the following errors repeatedly :

  Failed to execute: 0x80070057
  
  Hardware accelerator failed to decode picture

  I also start getting the following errors after a few seconds :

  co located POCs unavailable

  And the video is not displayed properly : I get a lot of artifacts all over the video and it is lagging. I checked the first error in the ffmpeg source code. It seems that IDirectXVideoDecoder_Execute fails because of an invalid parameter. Since this is happening withing ffmpeg, there must be something that I’m missing but I can’t figure out what. The only relevant post that I found with this error was because of multithreading but I set the thread_count to 1 before opening the codec.

  This issue is happening on my main computer which has the following specs :

  • i7-4790 CPU @ 3.6GHz
  • RAM 16 GB
  • Intel HD Graphics 4600
  • Windows 8.1

  The same issue is not happening on my second computer which has the following specs :

  • i7 4510U @ 2GHz
  • RAM 8 GB
  • NVIDIA GeForce GTX 750Ti
  • Windows 10

  If I use DXVAChecker on my main computer, it says that my graphics card supports DXVA2 for H264_VLD_*, and I can see that the calls to the Microsoft API are being made (DXVA2_DecodeDeviceCreated, DXVA2_DecodeDeviceBeginFrame, DXVA2_DecodeDeviceGetBuffer, DXVA2_DecodeDeviceExecute, DXVA2_DecodeDeviceEndFrame) while my video is playing.

  I also don’t see any increase of GPU usage (on either computer) between the version with hardware decoding and the version without ; however, I do see a decrease in CPU usage (not as much as I was expecting though). This is also very strange.

  Note that I tried both the Windows release available on the FFmpeg website, and a version that I compiled with —enable-dxva2. I have searched a lot already but I was unable to find what I’m doing wrong.

  Hopefully, someone can help me, or maybe point me to a better example ?