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• Output black when I decode h264 720p with ffmpeg

  6 décembre 2017, par José Marqueses Saxo

  First, sorry for my english. When I decode h264 720p in ardrone2.0 my output is black and I cant see anything.

  I have try to change the value of pCodecCtx->pix_fmt = AV_PIX_FMT_BGR24; to pCodecCtx->pix_fmt = AV_PIX_FMT_YUV420P; and the value of pCodecCtxH264->pix_fmt = AV_PIX_FMT_BGR24; to pCodecCtxH264->pix_fmt = AV_PIX_FMT_YUV420P; but my program crash. What am I doing wrong ?. Thank you, see part of my code :

  av_register_all();
  
  avcodec_register_all();
  
  avformat_network_init();
  
  
  
  // 1.2. Open video file
  
  if(avformat_open_input(&pFormatCtx, drone_addr, NULL, NULL) != 0) {
  
    mexPrintf("No conecct with Drone");
  
    EndVideo();
  
    return;
  
  }
  
  
  
  pCodec    = avcodec_find_decoder(AV_CODEC_ID_H264);
  
  
  
  pCodecCtx = avcodec_alloc_context3(pCodec);
  
  pCodecCtx->pix_fmt = AV_PIX_FMT_BGR24;
  
  pCodecCtx->skip_frame = AVDISCARD_DEFAULT;
  
  pCodecCtx->error_concealment = FF_EC_GUESS_MVS | FF_EC_DEBLOCK;
  
  pCodecCtx->err_recognition = AV_EF_CAREFUL;
  
  pCodecCtx->skip_loop_filter = AVDISCARD_DEFAULT;
  
  pCodecCtx->workaround_bugs = FF_BUG_AUTODETECT;
  
  pCodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
  
  pCodecCtx->codec_id = AV_CODEC_ID_H264;
  
  pCodecCtx->skip_idct = AVDISCARD_DEFAULT;
  
  pCodecCtx->width = 1280;
  
  pCodecCtx->height = 720;
  
  
  
  pCodecH264 = avcodec_find_decoder(AV_CODEC_ID_H264);
  
  pCodecCtxH264 = avcodec_alloc_context3(pCodecH264);
  
  
  
  
  
  pCodecCtxH264->pix_fmt = AV_PIX_FMT_BGR24;
  
  pCodecCtxH264->skip_frame = AVDISCARD_DEFAULT;
  
  pCodecCtxH264->error_concealment = FF_EC_GUESS_MVS | FF_EC_DEBLOCK;
  
  pCodecCtxH264->err_recognition = AV_EF_CAREFUL;
  
  pCodecCtxH264->skip_loop_filter = AVDISCARD_DEFAULT;
  
  pCodecCtxH264->workaround_bugs = FF_BUG_AUTODETECT;
  
  pCodecCtxH264->codec_type = AVMEDIA_TYPE_VIDEO;
  
  pCodecCtxH264->codec_id = AV_CODEC_ID_H264;
  
  pCodecCtxH264->skip_idct = AVDISCARD_DEFAULT;
  
  
  
  if(avcodec_open2(pCodecCtxH264, pCodecH264, &optionsDict) < 0)
  
  {
  
     mexPrintf("Error opening H264 codec");
  
     return ;
  
  }
  
  
  
  pFrame_BGR24 = av_frame_alloc();
  
  
  
  
  
  if(pFrame_BGR24 == NULL) {
  
     mexPrintf("Could not allocate pFrame_BGR24\n");
  
     return ;
  
  }
  
  
  
  // Determine required buffer size and allocate buffer
  
  
  
  buffer_BGR24 = 
  
  (uint8_t *)av_mallocz(av_image_get_buffer_size(AV_PIX_FMT_BGR24, 
  
  pCodecCtx->width, ((pCodecCtx->height == 720) ? 720 : pCodecCtx->height) * 
  
  sizeof(uint8_t)*3,1));
  
  
  
  // Assign buffer to image planes
  
  
  
  av_image_fill_arrays(pFrame_BGR24->data, pFrame_BGR24->linesize,
  
  buffer_BGR24,AV_PIX_FMT_BGR24, pCodecCtx->width, pCodecCtx->height,1);
  
  
  
  // format conversion context
  
  pConvertCtx_BGR24 = sws_getContext(pCodecCtx->width, pCodecCtx->height, 
  
  pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,  AV_PIX_FMT_BGR24, 
  
                                   SWS_BILINEAR | SWS_ACCURATE_RND, 0, 0, 0);
  
  
  
  // 1.6. get video frames
  
  pFrame = av_frame_alloc();
  
  
  
  av_init_packet(&packet);
  
  packet.data = NULL;
  
  packet.size = 0;
  
  }
  
  
  
  //Captura un frame
  
  void video::capture(mxArray *plhs[]) {
  
  
  
    if(av_read_frame(pFormatCtx, &packet) < 0){
  
        mexPrintf("Error al leer frame");
  
        return;
  
    }
  
     do {
  
         do {
  
            rest = avcodec_send_packet(pCodecCtxH264, &packet);
  
         } while(rest == AVERROR(EAGAIN));
  
  
  
         if(rest == AVERROR_EOF || rest == AVERROR(EINVAL)) {
  
                  printf("AVERROR(EAGAIN): %d, AVERROR_EOF: %d, 
  
                  AVERROR(EINVAL): %d\n", AVERROR(EAGAIN), AVERROR_EOF, 
  
                  AVERROR(EINVAL));
  
              printf("fe_read_frame: Frame getting error (%d)!\n", rest);
  
              return;
  
         }
  
  
  
         rest = avcodec_receive_frame(pCodecCtxH264, pFrame);
  
     } while(rest == AVERROR(EAGAIN));
  
  
  
     if(rest == AVERROR_EOF || rest == AVERROR(EINVAL)) {
  
  
  
      // An error or EOF occured,index break out and return what
  
      // we have so far.
  
        printf("AVERROR(EAGAIN): %d, AVERROR_EOF: %d, AVERROR(EINVAL): %d\n", 
  
        AVERROR(EAGAIN), AVERROR_EOF, AVERROR(EINVAL));
  
          printf("fe_read_frame: EOF or some othere decoding error (%d)!\n", 
  
          rest);
  
          return;
  
     }
  
  
  
  
  
     // 2.1.1. convert frame to GRAYSCALE [or BGR] for OpenCV
  
     sws_scale(pConvertCtx_BGR24,   (const uint8_t* const*)pFrame->data, 
  
         pFrame->linesize, 0,pCodecCtx->height,   pFrame_BGR24->data,   
  
               pFrame_BGR24->linesize);
  
  //}
  
     av_packet_unref(&packet);
  
     av_init_packet(&packet);
  
     mwSize dims[] = {(pCodecCtx->width)*((pCodecCtx->height == 720) ? 720 : 
  
     pCodecCtx->height)*sizeof(uint8_t)*3};
  
     plhs[0] = mxCreateNumericArray(1,dims,mxUINT8_CLASS, mxREAL);
  
      //plhs[0]=mxCreateDoubleMatrix(pCodecCtx->height,pCodecCtx-
  
      >width,mxREAL);
  
     point=mxGetPr(plhs[0]);
  
     memcpy(point, pFrame_BGR24->data[0],(pCodecCtx->width)*(pCodecCtx-
  
      >height)*sizeof(uint8_t)*3);
  
  }

• FFmpeg extracts black image from H264 stream

  8 juin 2022, par massivemoisture

  I have a C# application that receives H264 stream through a socket. I want to continuously get the latest image from that stream.

  


  Here's what I did with FFmpeg 5.0.1, just a rough sample to get ONE latest image, how I start FFmpeg :

  


  var ffmpegInfo = new ProcessStartInfo(FFMPEG_PATH);
ffmpegInfo.RedirectStandardInput = true;
ffmpegInfo.RedirectStandardOutput = true;
ffmpegInfo.RedirectStandardError = true;
ffmpegInfo.UseShellExecute = false;

ffmpegInfo.Arguments = "-i pipe: -f h264 -pix_fmt bgr24 -an -sn pipe:";

ffmpegInfo.UseShellExecute = false;
ffmpegInfo.CreateNoWindow = true;

Process myFFmpeg = new Process();
myFFmpeg.StartInfo = ffmpegInfo;
myFFmpeg.EnableRaisingEvents = true;
myFFmpeg.Start();

var inStream = myFFmpeg.StandardInput.BaseStream;
FileStream baseStream = myFFmpeg.StandardOutput.BaseStream as FileStream;
myFFmpeg.BeginErrorReadLine();


  


  Then I start a new thread to receive the stream through socket :

  


  // inStream is "myFFmpeg.StandardInput.BaseStream" from the code block above
var t = Task.Run(() => ReceiveStream(inStream));


  


  Next I read the output from FFmpeg :

  


  byte[] decoded = new byte[Width * Height * 3];
int numBytesToRead = Width * Height * 3;
int numBytesRead = 0;

while (numBytesToRead > 0)
{
   int n = baseStream.Read(decoded, 0, decoded.Length);
   Console.WriteLine($"Read {n} bytes");
   if (n == 0)
   {
      break;
   }              
      numBytesRead += n;
      numBytesToRead -= n;
}


  


  Lastly, I use ImageSharp library to save decoded byte array as a jpeg file.

  


  image.Save("test.jpeg", encoder);


  


  However, test.jpeg always comes out as a black image. What did I do wrong ?
Here's the stderr log that I got from ffmpeg :

  


  
  Duration: N/A, bitrate: N/A
  Stream #0:0: Video: h264 (High), yuv420p(tv, smpte170m/bt470bg/smpte170m, progressive), 1080x2256, 25 fps, 25 tbr, 1200k tbn
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Incompatible pixel format 'bgr24' for codec 'libx264', auto-selecting format 'yuv444p'
[libx264 @ 0x11b9068f0] using cpu capabilities: ARMv8 NEON
[libx264 @ 0x11b9068f0] profile High 4:4:4 Predictive, level 5.0, 4:4:4, 8-bit
Output #0, h264, to 'pipe:':
  Metadata:
    encoder         : Lavf59.16.100
  Stream #0:0: Video: h264, yuv444p(tv, smpte170m/bt470bg/smpte170m, progressive), 1080x2256, q=2-31, 25 fps, 25 tbn
    Metadata:
      encoder         : Lavc59.18.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame=    1 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x    
frame=   56 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x
frame=   87 fps= 83 q=28.0 size=     370kB time=00:00:01.16 bitrate=2610.6kbits/s speed=1.11x
frame=  118 fps= 75 q=28.0 size=     698kB time=00:00:02.40 bitrate=2381.4kbits/s speed=1.54x
frame=  154 fps= 75 q=28.0 size=    1083kB time=00:00:03.84 bitrate=2311.1kbits/s speed=1.86x
...


  


  Thank you !

  


  Edit : as suggested by @kesh, I have changed h264 to rawvideo, the arguments now are : -i pipe: -f rawvideo -pix_fmt bgr24 -an -sn pipe:

  


  Here's the output of ffmpeg :

  


  Input #0, h264, from 'pipe:':
  Duration: N/A, bitrate: N/A
  Stream #0:0: Video: h264 (High), yuv420p(tv, smpte170m/bt470bg/smpte170m, progressive), 1080x2256, 25 fps, 25 tbr, 1200k tbn
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
// About 9 of these "No accelerated colorspace..." message
[swscaler @ 0x128690000] [swscaler @ 0x1286a0000] No accelerated colorspace conversion found from yuv420p to bgr24.
Output #0, rawvideo, to 'pipe:':
  Metadata:
    encoder         : Lavf59.16.100
  Stream #0:0: Video: rawvideo (BGR[24] / 0x18524742), bgr24(pc, gbr/bt470bg/smpte170m, progressive), 1080x2256, q=2-31, 1461888 kb/s, 25 fps, 25 tbn
    Metadata:
      encoder         : Lavc59.18.100 rawvideo
frame=    1 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x
// FFmpeg outputs no more log after this


  


• Fill output video with black screen in case of missing the input stream or switch input UDP stream to another source

  13 mai 2018, par Omar Mahmoud

  I am using FFMPEG to record a streams from UDP sources, but unfortunately once the input stream missed, the ffmpeg stop recording, then append video to file once the stream observed by the server again.

  And as these recording files is time based so, I need fill video with black screen in case of missing the input stream.

  ffmpeg -i ’udp ://224.12.12.1:4000’ -t 00:45:00 -vcodec copy -acodec copy -f mpegts /record/eEs1526947.ts

  How can I do this, either by ffmpeg or other CLI based service/process ?