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• FFmpeg : Decoding AVPackets received from UDP socket

  8 août 2022, par strong_kobayashi

  I am trying to stream video frames encoded with FFmpeg from an Unity game to a client UI via UDP. To be specific, I am sending AVPackets (which contain the compressed frames, as far as I understand) from the server, which are then, on the client side, extracted as follows :

  



  inline UDPpacket* SDLGameClient::receiveData()
{
    if(SDLNet_UDP_Recv(socket, packet))
        return packet;
    else
        return NULL;
}

int main()
{
    ...
    // Initialize UDP
    ...
    UDPpacket *udpPacket;

    int i = 0;

    for(;;)
    {
        udpPacket = client->receiveData();

        if(udpPacket != nullptr)
        {
            i++;
            std::cout << "Packet " << i << " received!" << std::endl;

            AVPacket packet;
            av_init_packet(&packet);

            packet.data = new uint8_t[udpPacket->len];
            memcpy(packet.data, udpPacket->data, udpPacket->len);
            packet.size = udpPacket->len;

            ...


  



  To realize networking, I use the SDL_net library. Fragmenting, sending and receiving the packets seem to work without any problem. My question is, how do I decode the incoming AVPackets and stream the frames recorded in Unity to the client ?
I am aware that I need to use avcodec_send_packet and avcodec_receive_frame for decoding (since avcodec_decode_video2, that is used in many example decoding code, is deprecated), but when I do something like this :

  



  int ret = avcodec_send_packet(codecContext, &packet);
if(ret < 0 || ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
    std::cout << "avcodec_send_packet: " << ret << std::endl;
else
{
    while(ret >= 0)
    {
        ret = avcodec_receive_frame(codecContext, frame);
        if(ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
            std::cout << "avcodec_receive_frame: " << ret << std::endl;

        std::cout << "Frame: " << codecContext->frame_number << std::endl;
    }
}

av_packet_unref(packet);


  



  ret always returns a negative value (-22), so perhaps something is wrong with the AVPackets, or I'm sending the frames way too fast, I really have no clue :/

  



  Thanks in advance for any help !

  


• FFMPEG and DirectX Capture in C++

  13 décembre 2016, par tankyx

  I have a system that allows me to capture a window and save it as a mp4, using ffmpeg. I use gdigrab to capture the frame, but it is fairly slow (60ms per av_read_frame calls)

  I know I can capture a game using the DirectX API, but I don’t know how to convert the resulting BMP to an AVFrame.

  The following code is the DirectX code I use to capture the frame

  extern void* pBits;
  
  extern IDirect3DDevice9* g_pd3dDevice;
  
  IDirect3DSurface9* pSurface;
  
  g_pd3dDevice->CreateOffscreenPlainSurface(ScreenWidth, ScreenHeight,
  
                                        D3DFMT_A8R8G8B8, D3DPOOL_SCRATCH, 
  
                                        &pSurface, NULL);
  
  g_pd3dDevice->GetFrontBufferData(0, pSurface);
  
  D3DLOCKED_RECT lockedRect;
  
  pSurface->LockRect(&lockedRect,NULL,
  
                 D3DLOCK_NO_DIRTY_UPDATE|
  
                 D3DLOCK_NOSYSLOCK|D3DLOCK_READONLY)));
  
  for( int i=0 ; i < ScreenHeight ; i++)
  
  {
  
      memcpy( (BYTE*) pBits + i * ScreenWidth * BITSPERPIXEL / 8 , 
  
           (BYTE*) lockedRect.pBits + i* lockedRect.Pitch , 
  
           ScreenWidth * BITSPERPIXEL / 8);
  
  }
  
  g_pSurface->UnlockRect();
  
  pSurface->Release();

  And here is my read loop :

  {
  
      while (1) {
  
      if (av_read_frame(pFormatCtx, &packet) < 0 || exit)
  
          break;
  
      if (packet.stream_index == videoindex) {
  
          // Decode video frame
  
          av_packet_rescale_ts(&packet, { 1, std::stoi(pParser->GetVal("video-fps")) }, pCodecCtx->time_base);
  
          avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
  
  
          if (frameFinished) {
  
              pFrame->pts = i;
  
              i++;
  
              sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
              pFrameRGB->pts = pFrame->pts;
  
              enc.encodeFrame(pFrameRGB);
  
  
  
      }
  
      // Free the packet that was allocated by av_read_frame
  
      av_free_packet(&packet);
  
  }

  How can I create an AVFrame using the bmp I have, without using the av_read_frame ?

• avcodec/amfenc : Implement async_depth option

  7 novembre 2024, par Cameron Gutman

  avcodec/amfenc : Implement async_depth option
  This option, which is also available on other FFmpeg hardware encoders,
  
  allows the user to trade throughput for reduced output latency. This is
  
  useful for ultra low latency applications like game streaming.
  Signed-off-by : Cameron Gutman <aicommander@gmail.com>
  

  • [DH] libavcodec/amfenc.c
  • [DH] libavcodec/amfenc_av1.c
  • [DH] libavcodec/amfenc_h264.c
  • [DH] libavcodec/amfenc_hevc.c