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• How to Skip frames while decoding H264 stream ?

  16 septembre 2018, par TTGroup

  I’m using FFMPEG to decode H264 (or H265) RTSP Stream.

  My system have 2 software : Server and Client

  Server: Read frames from RTSP stream --> Forward frames to Client    
  
  Client: Receive frames from Server --> Decode --> Render

  I have implemented and it worked ok, but there is a case make my system work not good. That is when internet from Server - Client is slow, frames can not transfer real-time to Client.

  In present, I deal with this issue by Skip some frames (not send to Client) when the Queue is reached limit of count. The following is my summary code

  //At Server Software (include 2 threads A and B)
  
  //Thread A: Read AVPacket and forward to Client
  
  while(true)
  
  {
  
      AVPacket packet;
  
      av_init_packet(&packet);
  
      packet.size = 0;
  
      packet.data = NULL;
  
      int ret = AVERROR(EAGAIN);
  
      while (AVERROR(EAGAIN) == ret)
  
          ret = av_read_frame(pFormatCtx, &packet);
  
      if(packet.size > 0)
  
      {
  
          if(mySendQueue.count < 120) //limit 120 packet in queue
  
              mySendQueue.Enqueue(packet); ////Thread B will read from this queue, to send packets to Client via TCP socket
  
          else
  
              ;//SkipThisFrame ***: No send
  
      }
  
  }
  
  //Thread B: Send To Client via TCP Socket
  
  While(true)
  
  {
  
      AVPacket packet;
  
      if(mySendQueue.Dequeue(packet))
  
      {
  
          SendPacketToClient(packet);
  
      }
  
  }
  
  
  
  //At Server Software : Receive AVPacket from Server --> Decode --> Render
  
  While(true)
  
  {
  
      AVPacket packet;
  
      AVFrame frame;
  
      ReadPacketFromServer(packet);
  
      if (av_decode_asyn(pCodecCtx, &frame, &frameFinished, &packet) == RS_OK)
  
      {
  
          if (frameFinished)
  
          {
  
              RenderFrame(frame);
  
          }
  
      }           
  
  }
  
  UINT32 __clrcall av_decode_asyn(AVCodecContext *pCodecCtx, AVFrame *frame, int *frameFinished, AVPacket *packet)
  
  {
  
      int ret = -1;
  
      *frameFinished = 0;
  
      if (packet) 
  
      {
  
          ret = avcodec_send_packet(pCodecCtx, packet);
  
          // In particular, we don't expect AVERROR(EAGAIN), because we read all
  
          // decoded frames with avcodec_receive_frame() until done.
  
          if (ret < 0 && ret != AVERROR_EOF)
  
              return RS_NOT_OK;
  
      }
  
  
  
      ret = avcodec_receive_frame(pCodecCtx, frame);
  
      if (ret < 0 && ret != AVERROR(EAGAIN))
  
      {
  
          return RS_NOT_OK;
  
      }
  
      if (ret >= 0)
  
          *frameFinished = 1;
  
  
  
      return RS_OK;
  
  }

  My question is focus in line of code SkipThisFrame ***, this algorithm skip frame continuously, so it maybe make the decoder on Client occur unexpectedly error or Crash ?

  And when skip frame like that, make Client Render frames is not normally ?

  And someone call show me the proper algorithm to skip frames in my case ?

  Thank you very much !

• avformat/mxfenc : Set color siting to 0 for D10-MXF

  6 avril 2018, par Michael Niedermayer

  avformat/mxfenc : Set color siting to 0 for D10-MXF
  SMPTE 386M (D-10) lists 4 as value to be used
  
  SMPTE 377-1-2009 says
  
      "The definitions of 00h (coSiting) and 04h (Rec 601) are equivalent. The value of 04h is deprecated. New
  
       MXF encoders shall use the value of 00h instead."
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/mxfenc.c

• avformat/dashenc : Set mp4 as the default format for VP9

  23 avril 2018, par Karthick Jeyapal

  avformat/dashenc : Set mp4 as the default format for VP9
  There is a separate muxer(webmdashenc.c) for supporting VP9+webm output in DASH.
  
  Hence in this muxer we will focus on supporting VP9 in MP4
  
  Have verified playout support of VP9+MP4 in Chrome and Firefox.
  

  • [DH] libavformat/dashenc.c