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• avcodec/v4l2_context : Drop empty packet while draining

  10 mai 2020, par Andriy Gelman

  avcodec/v4l2_context : Drop empty packet while draining
  v4l2_m2m devices may send an empty packet/frame while draining
  
  to indicate that all capture buffers have been flushed.
  Currently, the empty packet/frame is not handled correctly :
  
  When encoding, the empty packet is forwarded to the muxer, usually
  
  creating warnings.
  
  When decoding, a reference to the memory is created anyway. Since in
  
  the past this memory contained a decoded frame, it results in an extra
  
  frame being decoded.
  This commit discards the empty packet/frame.
  References :
  
  linux/Documentation/media/uapi/v4l/dev-decoder.rst :
      "The last buffer may be empty (with :c:type :`v4l2_buffer` bytesused = 0)
  
       and in that case it must be ignored by the client, as it does not
  
       contain a decoded frame."
  linux/Documentation/media/uapi/media/v4l/vidioc-encoder-cmd.rst :
      "...This buffer may be empty, indicated by the
  
       driver setting the ``bytesused`` field to 0."
  Reviewed-by : Ming Qian <ming.qian@nxp.com>
  
  Signed-off-by : Andriy Gelman <andriy.gelman@gmail.com>
  

  • [DH] libavcodec/v4l2_context.c

• ffmpeg with h264_qsv encoder

  24 juin 2015, par Dmitry Vasilyev

  We use the following libraries :
  1. ffmpeg library for encoding and decoding
  2. live555 library for streaming (RTSP)

  Machine configuration is CPU Intel(R) Atom(TM) E3845 and Windows 8.1 with Intel driver that includes libmfxhw32.dll.

  We also try to use Intel Quick Sync Video(QSV) technology inside ffmpeg library. ffmpeg has been configured with —enable-libmfx and includes h264_qsv encoder.
  The method avcodec_find_encoder_by_name("h264_qsv") returns handle to "h264" codec instance.

  bool aEncoder::Initialize(std::string& container)
  
  {
  
      bool res = false;
  
  
  
      AVCodec* av_codec = NULL;
  
      av_codec = avcodec_find_encoder_by_name("h264_qsv"); //first 
  
      if(av_codec == NULL)
  
      {
  
          return false;
  
      }
  
  
  
      avformat_alloc_output_context2(&m_pFormatContext, NULL, container.c_str(), NULL);
  
      if(!m_pFormatContext)
  
      {
  
          return false;
  
      }
  
  
  
      m_pOutFormat = m_pFormatContext->oformat;
  
      m_pOutFormat->video_codec = av_codec->id;
  
  
  
      return true;
  
  }
  
  
  
  AVStream *aEncoder::AddVideoStream(AVFormatContext *pContext, AVCodec *codec, AVCodecID codecId, void *realStreamer)
  
  {
  
      AVCodecContext *pCodecCxt = NULL;
  
      AVStream *stream = NULL;
  
      stream = avformat_new_stream(pContext, codec);
  
      if (!stream)
  
      {
  
          return NULL;
  
      }
  
  
  
      pCodecCxt = stream->codec;
  
      pCodecCxt->hwaccel_context =(void *)&qsvConf; //second
  
  
  
      //...
  
  }

  Could you please reply to the question below :
  1. How can we initialize "h264_qsv" correctly ?
  2. How can we check that "h264_qsv" is used duiring encoding ?

  Thank You in advance for your help.

• vaapi_encode : Support configurable slices

  23 septembre 2018, par Mark Thompson

  vaapi_encode : Support configurable slices
  This adds common code to query driver support and set appropriate
  
  address/size information for each slice.  It only supports rectangular
  
  slices for now, since that is the most common use-case.
  

  • [DH] doc/encoders.texi
  • [DH] libavcodec/vaapi_encode.c
  • [DH] libavcodec/vaapi_encode.h