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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

• Oculus Rift in .Net

  12 novembre 2015, par Guy Levin

  I’m trying to use Oculus Rift DK2 with .Net in order to display live video stream

  I’m able to sample the video (rtmp) using Emgu or ffmpeg, and then display it with SharpDX on screen.

  But I’m struggling to make oculus rift to display it. Now I’m using SharpOVR wrapper.

  Any suggestions will be highly appreciated

  This is some of the code :

  program.cs :

   using (var program = new RiftGame())
  
              program.Run();

  RiftGame.cs

  using SharpOVR;
  
  using SharpDX;
  
  ...
  
  
  
  Queue _images;
  
  
  
  void _tmr_Tick(object sender, EventArgs e)
  
  {
  
      if (_capture == null)
  
      {
  
          _capture = new Capture(Emgu.CV.CvEnum.CaptureType.Any);
  
      }
  
  
  
      System.Drawing.Bitmap image = _capture.QueryFrame().Bitmap;
  
      _images.Enqueue(image);
  
  }     
  
  
  
  
  
  protected override void Draw(GameTime gameTime)
  
  {
  
      GraphicsDevice.Clear(Color.CornflowerBlue);
  
  
  
      _graphicsDeviceManager.PreferredBackBufferWidth = 480;
  
      _graphicsDeviceManager.PreferredBackBufferHeight = 800;
  
  
  
      var image = _images.Dequeue();
  
  
  
      using (MemoryStream ms = new MemoryStream())
  
      {
  
  
  
          image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
  
          ms.Position = 0;
  
          tex = Texture2D.Load(GraphicsDevice, ms);                        
  
      }
  
  
  
  
  
      Vector2 planePosition = new Vector2(
  
         (this.GraphicsDevice.BackBuffer.Width / 2.0f) - (tex.Width / 2.0f),
  
         (this.GraphicsDevice.BackBuffer.Height / 2.0f) - (tex.Height / 2.0f));
  
  
  
      _spriteBatch.Begin();
  
  
  
      _spriteBatch.Draw(tex, planePosition, Color.White);
  
  
  
      _spriteBatch.End();
  
  
  
      _spriteBatch.Begin(SpriteSortMode.Deferred, GraphicsDevice.BlendStates.NonPremultiplied);
  
      _spriteBatch.End();
  
  
  
      base.Draw(gameTime);
  
  }

• avfilter/avf_showcqt : rewrite showcqt and add features

  25 octobre 2015, par Muhammad Faiz

  avfilter/avf_showcqt : rewrite showcqt and add features
  add yuv444p, yuv422p, and yuv420p output format (lower cpu usage
  
  on ffplay playback because it does not do format conversion)
  
  custom size with size/s option (fullhd option is deprecated)
  
  custom layout with bar_h, axis_h, and sono_h option
  
  support rational frame rate (within fps/r/rate option)
  
  relaxed frame rate restriction (support fractional sample step)
  
  support all input sample rates
  
  separate sonogram and bargraph volume (with volume/sono_v and
  
  volume2/bar_v)
  
  timeclamp option alias (timeclamp/tc)
  
  fcount option
  
  gamma option alias (gamma/sono_g and gamma2/bar_g)
  
  support custom frequency range (basefreq and endfreq)
  
  support drawing axis using external image file (axisfile option)
  
  alias for disabling drawing to axis (text/axis)
  
  possibility to optimize it using arch specific asm code
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] doc/filters.texi
  • [DH] libavfilter/avf_showcqt.c
  • [DH] libavfilter/avf_showcqt.h
  • [DH] libavfilter/version.h