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• Multiple frames lost if I use av_read_frame in FFmpeg

  12 juin 2015, par Krishna

  I have an HEVC sequence with 3500 frames and I am writing a decoder for reading it (read frame by frame and dump to yuv). In my main(), I have a for loop that calls a decoder() 3500 times (I am assuming at this stage that the main() knows how many frames there are).

  So, for every call to decoder(), I need a complete frame to be returned. This is what the decoder() looks like..

  bool decode(pFormatCtx, pCodecCtx)
  
  {
  
      int gotaFrame=0;
  
  
  
      while (gotaFrame==0) {
  
  
  
          printf("1\t");
  
  
  
          if ( !av_read_frame(pFormatCtx, &packet) ) { 
  
              if(packet.stream_index==videoStreamIndex) {
  
  
  
                  // try decoding
  
                  avcodec_decode_video2(pCodecCtx, pFrame, &gotaFrame, &packet);
  
  
  
                  if (gotaFrame) {  // decode success.
  
  
  
                      printf("2\t");
  
  
  
                      // dump to yuv ... not shown here. 
  
  
  
                      // cleanup
  
                      av_frame_unref(pFrame);
  
                      av_frame_free(&pFrame);
  
                      av_free_packet(&packet);
  
  
  
                      return true;
  
                  }
  
              }
  
          }
  
      }
  
  }

  The behavior is like this : 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 2 1 2 ...... it looks like it reads several frames before decoding one ? The first frame is an I-frame, so shouldn’t that be decoded right away ?

  With this code, I end up losing the several frames (indicated by the series of 1s). Can someone help me out here ? Is there something I am doing wrong in my code ?

  Update : the test clip is video-only. No audio.

• Using ffmpeg avcodec_decode_video2 got_picture_ptr returns 0

  3 septembre 2014, par kaiken

  I’m trying to playback the gopro live feed which consists of a series of very short .ts files encoded using H264. I tested it on videos with different containers (mkv,avi,mp4) and different codecs (MPEG4, H264, MSVIDEO1). However, the files from the gopro always returns got_picture_ptr as 0 from avcodec_decode_video2 while the function returns the packet’s size. If I use ffplay or vlc it play the file without problem. I’m not sure what I’m doing wrong. I’m not very experienced with ffmpeg or video in general.

  Here is my test code. I based it off of this tutorial which is out of date but I was able to update the depreciated functions.

  AVFormatContext *pFormatCtx = NULL;
  
  AVCodecContext *pCodecCtx;
  
  AVStream *pStream = NULL;
  
  int videoStream;
  
  AVCodec *pCodec;
  
  AVFrame *pFrame=NULL, *pFrameRGB=NULL;
  
  HBITMAP membmp;
  
  int widht,height;
  
  BYTE *membits;
  
  int frameFinished;
  
  AVPacket packet;
  
  img_convert_ctx = NULL;
  
  uint8_t *buffer;
  
  int numBytes;
  
  
  
  // Open video file
  
  if(avformat_open_input(&pFormatCtx,params->fname,NULL,NULL)!=0)
  
     return -1;
  
  // Retrieve stream information
  
  if(avformat_find_stream_info(pFormatCtx,NULL)<0)
  
     return -1;
  
  //av_dump_format(pFormatCtx, 0, path, 0);
  
  
  
  // Find the first video stream
  
  for(int i=0; inb_streams; i++)
  
     if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
  
     {
  
        pStream=pFormatCtx->streams[i];
  
        videoStream = i;
  
        break;
  
     }
  
  if(pStream==NULL)
  
     return -1; // Didn't find a video stream
  
  
  
  // Get a pointer to the codec context for the video stream
  
  pCodecCtx=pStream->codec;
  
  
  
  // Find the decoder for the video stream
  
  pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
  
  if(pCodec==NULL) {
  
     fprintf(stderr, "Unsupported codec!\n");
  
     return -1; // Codec not found
  
  }
  
  
  
  // Open codec
  
  if(avcodec_open2(pCodecCtx, pCodec, NULL)<0)
  
     return -1;
  
  
  
  // Allocate an AVFrame structure
  
  pFrame=avcodec_alloc_frame();
  
  pFrameRGB=avcodec_alloc_frame();
  
  if(pFrameRGB==NULL)
  
     return -1;
  
  
  
  MakeBitmap(*params->memdc,membmp,(void**)&membits,pCodecCtx->width,pCodecCtx->height);
  
  // Assign appropriate parts of buffer to image planes in pFrameRGB
  
  // Note that pFrameRGB is an AVFrame, but AVFrame is a superset
  
  // of AVPicture
  
  avpicture_fill((AVPicture *)pFrameRGB, membits, PIX_FMT_RGB24,
  
                 pCodecCtx->width, pCodecCtx->height);
  
  
  
  while (av_read_frame(pFormatCtx, &packet) >= 0)
  
  {
  
      // Is this a packet from the video stream?
  
      if (packet.stream_index == videoStream)
  
      {
  
          // Decode video frame
  
          int bytesUsed = avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
          // Did we get a video frame?
  
          if(frameFinished)
  
          {
  
             //Do stuff with frame
  
          }
  
      }
  
      // Free the packet that was allocated by av_read_frame
  
      av_free_packet(&packet);
  
      //if(i++>500)
  
      //   break;
  
  }
  
  DeleteObject(membmp);
  
  
  
  
  
  // Free the frames
  
  av_free(pFrameRGB);
  
  av_free(pFrame);
  
  // Close the codec
  
  avcodec_close(pCodecCtx);
  
  // Close the video file
  
  avformat_close_input(&pFormatCtx);
  
  
  
  return  -1;

  For reference I’m doing this on Windows with the versions of the dlls :

  • avcodec-56.dll
  • avdevice-56.dll
  • avfilter-5.dll
  • avformat-56.dll
  • avutil-54.dll
  • postproc-53.dll
  • swresample-1.dll
  • swscale-3.dll

  and sample video file https://www.dropbox.com/s/htlinnv3qk5dfiu/amba_hls-2.ts?dl=0

• aws-lambda not recognizing ffmpeg command

  28 août 2019, par Jay

  AWS Lambda function running Python is not recognizing -filter_complex

     os.system(f"/tmp/ffmpeg -f lavfi -i color=black -i 2.gif -filter_complex [0][1]scale2ref[bg][gif];[bg]setsar=1[bg];[bg][gif]overlay=shortest=1 2.mp4")

  Error from CloudWatch :

  sh: -filter_complex: command not found
  
  
  
  Running: 
  
  ffmpeg version N-48801-g06ba4783a0-static https://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2019 the FFmpeg developers

  I think I know the problem. Somehow I need to put Quotes around :

  "[0][1]scale2ref[bg][gif];[bg]setsar=1[bg];[bg][gif]overlay=shortest=1"