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• ffmpeg av_read_frame return error code -5

  17 septembre 2020, par Jianhua Zhu

  I use dll of ffmpeg read the USB camera, display the picture on the control, and save the image to the file. At first, the reading is normal. The sound and image can be saved. But after reading for a few minutes, data can not be read, av_read_frame return error code is - 5, and the camera is automatically turned off. Direct use ffmpeg.exe when I go to read the camera and save the file, it won't be a problem for hours. Anybody can you tell me how to return - 5 error code and how to deal with it ?
ffmpeg version is 4.2.3
The code like this :

  


  while (1)
{
  if ((ret = av_read_frame(m_pVidFmtCtx, dec_pkt)) == 0)
  {
    ret = avcodec_send_packet(m_pVidFmtCtx->streams[dec_pkt->stream_index]->codec, dec_pkt);
    while(ret >= 0)
    {
      ret = avcodec_receive_frame(m_pVidFmtCtx->streams[dec_pkt->stream_index]->codec, pframe);
      sws_scale(img_rgb_ctx, pframe->data, pframe->linesize, 0, cy, dstData, dstLinesize);
      var bitmap = new Bitmap(dstWidth, dstHeight, dstLinesize[0], PixelFormat.Format24bppRgb, convertedFrameBufferPtr);
    }
  }
  else
  {
    printf("Error code: %d", ret); // Here ret is -5
  }
}


  


• How to optimize YUV to RGB color conversion code

  1er février 2016, par user_12

  I have written a function to convert an image in YUV420P to RGB but it is taking 30 millisecond to convert an image (size : 1280 x 720) into RGB, but when I am using ffmpeg function ( as this) to convert YUV image into RGB its taking only 2 millisecond for the same image. What is the problem with my code ? How can I optimize the code that I have written ??
  My code is given below

   int step = origImage->widthStep;
  
   uchar *data = (uchar *)origImage->imageData; 
  
   int size = origImage->width * origImage->height;
  
   IplImage* img1 = cvCreateImage(cvGetSize(origImage), IPL_DEPTH_8U, 3);
  
  
  
      for (int i = 0; iheight; i++)
  
      {
  
        for (int j=0; jwidth; j++)
  
        {
  
          float Y = data[i*step + j];
  
          float U = data[ (int)(size + (i/2)*(step/2)  + j/2) ];
  
          float V = data[ (int)(size*1.25 + (i/2)*(step/2) + j/2)];
  
  
  
          float R = Y + 1.402 * (V - 128);
  
          float G = Y - 0.344 * (U - 128) - 0.714 * (V - 128);
  
          float B = Y + 1.772 * (U - 128);
  
  
  
  
  
          if (R < 0){ R = 0; } if (G < 0){ G = 0; } if (B < 0){ B = 0; }
  
          if (R > 255 ){ R = 255; } if (G > 255) { G = 255; } if (B > 255) { B = 255; }
  
  
  
          cvSet2D(img1, i, j,cvScalar(B,G,R));
  
        }
  
      }

• Sample RTP code to stream x264 data

  5 août 2016, par Ajay Ponna Venkatesh

  I am using x264 library to encode frames and I need to stream it to a client which will receive the frame, decode and render it.
  Currently, I have borrowed the code from OBS to stream through RTMP and have written a client using FFMPEG’s RTMP code to receive this data. BUT RTMP works on TCP and I now need to stream over UDP. OBS doesn’t seem to support any other protocols than RTMP.

  So, I decided to use RTP. I can write a client to receive and decode using FFMPEG since it supports RTP just like RTMP. Can anyone please help me with sample code to stream x264 encoded data through plain RTP ? (I don’t want to complicate by using RTSP etc. along with RTP).

  The requirement is simple. Say, I use ffplay -> ffplay.exe rtp ://127.0.0.1:17000 then I want this sample code to be able to send data through RTP (over UDP) and ffplay should be able to play. I can take it over from there. Thanks in advance !

  -Ajay