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• Revision 8d3d2b76f3 : Tx size selection enhancements (1) Refines the modeling function and uses that

  22 juin 2013, par Deb Mukherjee

  Changed Paths :
   Modify /vp9/common/vp9_blockd.h

  
   Modify /vp9/encoder/vp9_encodeframe.c

  
   Modify /vp9/encoder/vp9_onyx_if.c

  
   Modify /vp9/encoder/vp9_onyx_int.h

  
   Modify /vp9/encoder/vp9_rdopt.c

  
  
  Tx size selection enhancements

  (1) Refines the modeling function and uses that to add some speed
  features. Specifically, intead of using a flag use_largest_txfm as
  a speed feature, an enum tx_size_search_method is used, of which
  two of the types are USE_FULL_RD and USE_LARGESTALL. Two other
  new types are added :
  USE_LARGESTINTRA (use largest only for intra)
  USE_LARGESTINTRA_MODELINTER (use largest for intra, and model for
  inter)

  (2) Another change is that the framework for deciding transform type
  is simplified to use a heuristic count based method rather than
  an rd based method using txfm_cache. In practice the new method
  is found to work just as well - with derf only -0.01 down.
  The new method is more compatible with the new framework where
  certain rd costs are based on full rd and certain others are
  based on modeled rd or are not computed. In this patch the existing
  rd based method is still kept for use in the USE_FULL_RD mode.
  In the other modes, the count based method is used.
  However the recommendation is to remove it eventually since the
  benefit is limited, and will remove a lot of complications in
  the code

  (3) Finally a bug is fixed with the existing use_largest_txfm speed feature
  that causes mismatches when the lossless mode and 4x4 WH transform is
  forced.

  Results on derf :
  USE_FULL_RD : +0.03% (due to change in the tables), 0% encode time reduction
  USE_LARGESTINTRA : -0.21%, 15% encode time reduction (this one is a
  pretty good compromise)
  USE_LARGESTINTRA_MODELINTER : -0.98%, 22% encode time reduction
  (currently the benefit of modeling is limited for txfm size selection,
  but keeping this enum as a placeholder) .
  USE_LARGESTALL : -1.05%, 27% encode-time reduction (same as existing
  use_largest_txfm speed feature).

  Change-Id : I4d60a5f9ce78fbc90cddf2f97ed91d8bc0d4f936

• How to encode with ffmpeg if number of images smaller than GOP size

  10 avril 2013, par theateist

  The code bellow creates mp4 video file from jpeg images. When number of images is greater than GOP size the encoding success and after 10th image gotPacket that returned by avcodec_encode_video2 is > 0.

  BUT when number of images is smaller than GOP size gotPacket is always = 0 and therefore no images written to the file.

  My guess is that avcodec_encode_video2 allocates buffer with length equals to GOP size and until it won't be full gotPacket will be 0.

  My question is how to force avcodec_encode_video2 to encode even if it's buffer is not full ?

  ...
  
  _outStream->codec.gop_size = 10;
  
  _outStream->codec.keyint_min = 10;
  
  ...
  
  
  
  AVFrame* frame = getFrame();
  
  
  
  
  
  AVPacket packet;
  
  av_init_packet(&packet);
  
  packet.data = NULL;
  
  packet.size = 0;
  
  
  
  int gotPacket = 0;
  
  if (avcodec_encode_video2(_outStream->codec, &packet, frame, &gotPacket) < 0)
  
      throw std::runtime_error("failed to encode frame");
  
  
  
  if (gotPacket)
  
  {
  
      ...
  
      if (av_write_frame(_outContainer.get(), &packet) < 0)
  
          throw std::runtime_error("failed to write frame");      
  
      av_free_packet(&packet);
  
  }

• Revision 42f31923b0 : BITSTREAM - CLARIFICATION OF MV SIZE RANGE The codec should effectively run wit

  28 septembre 2013, par Jingning Han

  Changed Paths :
   Modify /vp9/common/vp9_entropymv.h

  
   Modify /vp9/decoder/vp9_decodemv.c

  
  
  BITSTREAM - CLARIFICATION OF MV SIZE RANGE

  The codec should effectively run with motion vector of range (-2048, 2047)
  in full pixels, for sequences of 1080p and below. Add assertions to clarify
  this behavior.

  Change-Id : Ia0cac28249f587d8f8882205228fa480263ab313