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 I based it off of this tutorial which is out of date but I was able to update the depreciated functions.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

• arm : Consistently use proper interworking function returns

  3 octobre 2024, par Martin Storsjö

  arm : Consistently use proper interworking function returns
  Use "bx lr", or "pop lr", which do proper mode switching
  
  between thumb and arm modes. A plain "mov pc, lr" does not switch
  
  from thumb mode to arm mode (while in arm mode, it does switch
  
  mode for a thumb caller).
  This is normally not an issue, as CONFIG_THUMB only is enabled if
  
  the C compiler defaults to thumb ; but stick to patterns that can
  
  do mode switching if needed, for consistency.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libswresample/arm/resample.S
  • [DH] libswscale/arm/hscale.S
  • [DH] libswscale/arm/output.S
  • [DH] libswscale/arm/yuv2rgb_neon.S

• python imageio.get_reader() returns format error

  19 août 2020, par tristan_jia

  import imageio

reader = imageio.get_reader("./t.mp4")


  


  As shown above, with python 3.6.10, it returns :

  


  >>> reader = imageio.get_reader("../")&#xA;Traceback (most recent call last):&#xA;  File "<stdin>", line 1, in <module>&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/core/functions.py", line 129, in get_reader&#xA;    return format.get_reader(request)&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/core/format.py", line 168, in get_reader&#xA;    return self.Reader(self, request)&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/core/format.py", line 217, in __init__&#xA;    self._open(**self.request.kwargs.copy())&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 357, in _open&#xA;    self._initialize()&#xA;  File "/home/tristan_jia/workspace/py3.6/venv/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 430, in _initialize&#xA;    shell=ISWIN)&#xA;  File "/usr/lib64/python3.6/subprocess.py", line 729, in __init__&#xA;    restore_signals, start_new_session)&#xA;  File "/usr/lib64/python3.6/subprocess.py", line 1364, in _execute_child&#xA;    raise child_exception_type(errno_num, err_msg, err_filename)&#xA;OSError: [Errno 8] Exec format error: &#x27;/home/tristan_jia/.imageio/ffmpeg/ffmpeg-linux64-v3.3.1&#x27;&#xA;&#xA;</module></stdin>

  


  I searched everywhere but haven't seen any similar questions. The script runs on Opensuse Leap 15.1, is it related to the system I use ?