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• cannot resolve variable PIX_FMT_RGB24, ffmpeg source code install with the newest version [duplicate]

  10 août 2016, par NacyL

  This question already has an answer here :

  • FFMPEG : ‘PIX_FMT_BGR24’ was not declared in this scope
    
    1 answer
    

  i installed the ffmpeg from source code according https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu, and write a test file to save ppm file from a video, but the code cannot reslove PIX_FMT_RGB24, i write the code as below :

  int main() {
  
      // Initalizing these to NULL prevents segfaults!
  
      AVFormatContext   *pFormatCtx = NULL;
  
      int               i, videoStream;
  
      AVCodecContext    *pCodecCtxOrig = NULL;
  
      AVCodecContext    *pCodecCtx = NULL;
  
      AVCodec           *pCodec = NULL;
  
      AVFrame           *pFrame = NULL;
  
      AVFrame           *pFrameRGB = NULL;
  
      AVPacket          packet;
  
      int               frameFinished;
  
      int               numBytes;
  
      uint8_t           *buffer = NULL;
  
      struct SwsContext *sws_ctx = NULL;
  
  
  
      const char* url = "/home/liulijuan/bin/test.mp4";
  
  
  
      // [1] Register all formats and codecs
  
      av_register_all();
  
  
  
      // [2] Open video file
  
      if(avformat_open_input(&pFormatCtx, url, NULL, NULL)!=0)
  
          return -1; // Couldn't open file
  
  
  
      // [3] Retrieve stream information
  
      if(avformat_find_stream_info(pFormatCtx, NULL)<0)
  
          return -1; // Couldn't find stream information
  
  
  
      // Dump information about file onto standard error
  
      av_dump_format(pFormatCtx, 0, url, 0);
  
  
  
      // Find the first video stream
  
      videoStream=-1;
  
      for(i=0; inb_streams; i++)
  
          if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) {
  
              videoStream=i;
  
              break;
  
          }
  
      if(videoStream==-1)
  
          return -1; // Didn't find a video stream
  
  
  
      // Get a pointer to the codec context for the video stream
  
      pCodecCtxOrig=pFormatCtx->streams[videoStream]->codec;
  
      // Find the decoder for the video stream
  
      pCodec=avcodec_find_decoder(pCodecCtxOrig->codec_id);
  
      if(pCodec==NULL) {
  
          fprintf(stderr, "Unsupported codec!\n");
  
          return -1; // Codec not found
  
      }
  
      // Copy context
  
      pCodecCtx = avcodec_alloc_context3(pCodec);
  
      if(avcodec_copy_context(pCodecCtx, pCodecCtxOrig) != 0) {
  
          fprintf(stderr, "Couldn't copy codec context");
  
          return -1; // Error copying codec context
  
      }
  
  
  
      // Open codec
  
      if(avcodec_open2(pCodecCtx, pCodec, NULL)<0)
  
          return -1; // Could not open codec
  
  
  
      // Allocate video frame
  
      pFrame=av_frame_alloc();
  
  
  
      // Allocate an AVFrame structure
  
      pFrameRGB=av_frame_alloc();
  
      if(pFrameRGB==NULL)
  
          return -1;
  
  
  
      // Determine required buffer size and allocate buffer
  
      numBytes=avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,
  
                                  pCodecCtx->height);
  
      buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
  
  
  
      // 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, buffer, PIX_FMT_RGB24,
  
                     pCodecCtx->width, pCodecCtx->height);
  
  
  
      // initialize SWS context for software scaling
  
      sws_ctx = sws_getContext(pCodecCtx->width,
  
                               pCodecCtx->height,
  
                               pCodecCtx->pix_fmt,
  
                               pCodecCtx->width,
  
                               pCodecCtx->height,
  
                               PIX_FMT_RGB24,
  
                               SWS_BILINEAR,
  
                               NULL,
  
                               NULL,
  
                               NULL
  
      );
  
  
  
      // [4] Read frames and save first five frames to disk
  
      i=0;
  
      while(av_read_frame(pFormatCtx, &packet)>=0) {
  
          // Is this a packet from the video stream?
  
          if(packet.stream_index==videoStream) {
  
              // Decode video frame
  
              avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
  
  
              // Did we get a video frame?
  
              if(frameFinished) {
  
                  // Convert the image from its native format to RGB
  
                  sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,
  
                            pFrame->linesize, 0, pCodecCtx->height,
  
                            pFrameRGB->data, pFrameRGB->linesize);
  
  
  
                  // Save the frame to disk
  
                  if(++i<=5)
  
                      SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height,
  
                                i);
  
              }
  
          }
  
  
  
          // Free the packet that was allocated by av_read_frame
  
          av_free_packet(&packet);
  
      }
  
  
  
      // Free the RGB image
  
      av_free(buffer);
  
      av_frame_free(&pFrameRGB);
  
  
  
      // Free the YUV frame
  
      av_frame_free(&pFrame);
  
  
  
      // Close the codecs
  
      avcodec_close(pCodecCtx);
  
      avcodec_close(pCodecCtxOrig);
  
  
  
      // Close the video file
  
      avformat_close_input(&pFormatCtx);
  
  
  
      return 0;
  
  }

  so i replace PIX_FMT_RGB24 with AV_PIX_FMT_RGB24, but i cannot open the saved ppm file, the save code as below :

  void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame) {
  
      FILE *pFile;
  
      char szFilename[32];
  
      int  y;
  
  
  
      printf("start save frame ...\n");
  
      // Open file
  
      sprintf(szFilename, "/home/liulijuan/frame%d.ppm", iFrame);
  
      pFile=fopen(szFilename, "wb");
  
      if(pFile==NULL)
  
          return;
  
  
  
      printf("start write header ...\n");
  
      // Write header
  
      fprintf(pFile, "/P6\n%d %d\n255\n", width, height);
  
  
  
      // Write pixel data
  
      for(y=0; ydata[0]+y*pFrame->linesize[0], 1, width*3, pFile);
  
  
  
      // Close file
  
      fclose(pFile);
  
      printf("close file ...\n");
  
  }

  so, what’s wrong with this code ?

• Repairing corrupt MOV file

  28 août 2016, par Simon Ridley

  I’m attempting to recover / repair MOV files from a formatted SD card. In the first instance I’ve made a copy of the physical disk using the unix command-line utility "DD". Once that completed I’ve used a working MOV file from the same recording device as a reference file to manually extract the required files using a Hex editor and Python.

  I have attempted to use other recovery tools such as Photorec, and X-Ways, however the extractions appear damaged. This is why I’m using a Hex editor to manually inspect the data to determine what is damaged.

  The software FFMPEG is reporting "moov atom not found" when attempting to process the damaged MOV file.

  When the file is examined in a hex editor I can clearly see that the header appears intact. Offsets 4 to 10 show the ’ftypqt’ signature, then offsets 17 and 16 display ’qt’ and finally the ’mdat’ identifier is at offsets 36 to 39. This is identical to the reference file I have. The mdat container doesn’t appear to finish until ’moov’ which is found at offset 733093392 followed by ’lmvhd’.

  This all appears in the reference file too and as far as I can tell all seems intact. am I correct in thinking that the mdat data is broken in chunks, this is possibly what is referred to as atoms ?

  In which case I appreciate that the data could be damaged somewhere within the mdat. Is it possible to extract the raw data out and rebuild the container ? I’m happy to attempt this with python but I need to understand the structure of the file in more detail. Can anyone help with this please ?

• ffmpeg sws_scale converting from YUV420P to RGB24 results in wrong color values

  3 novembre 2016, par Drazurh

  I’m using sws_scale to convert a video from YUV420P to RGB24. The resulting RGB values are wrong, looking much more saturated/contrasted. For example, the first pixel should have an RGB value of (223,73,30) but using sws_scale results in (153,0,0).

  Here’s the code I’m using :

  uint8_t *buffer = NULL;
  
  int numBytes;
  
  // Determine required buffer size and allocate buffer
  
  numBytes=avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,
  
                             pCodecCtx->height);
  
  buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
  
  
  
  // Assign appropriate parts of buffer to image planes in pFrameRGB
  
  // Note that pFrameRGB is an AVFrame, but AVFrame is a superset
  
  // of AVPicture
  
  std::cout << "Filling picture of size " << pCodecCtx->width <<" x "<height << std::endl;
  
  avpicture_fill((AVPicture *)pFrameRGB, buffer, PIX_FMT_RGB24,
  
                  pCodecCtx->width, pCodecCtx->height);
  
  
  
  
  
  
  
  // initialize SWS context for software scaling
  
  std::cout << "initializing SWS context\n";
  
  sws_ctx = sws_getContext(pCodecCtx->width,
  
      pCodecCtx->height,
  
      pCodecCtx->pix_fmt,
  
      pCodecCtx->width,
  
      pCodecCtx->height,
  
      PIX_FMT_RGB24,
  
      SWS_FAST_BILINEAR,
  
      NULL,
  
      NULL,
  
      NULL
  
  );
  
  
  
  while(frameFinished == 0)
  
  {
  
      if(av_read_frame(pFormatCtx, &packet)<0){
  
          std::cerr << "Could not read frame!\n";
  
          return false;
  
      }
  
  
  
      if(packet.stream_index==videoStream)
  
      {
  
          avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
      }
  
  
  
  }
  
  
  
  sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,
  
            pFrame->linesize, 0, pCodecCtx->height,
  
            pFrameRGB->data, pFrameRGB->linesize);

  The values in pFrameRGB are incorrect. I’ve tried troubleshooting this for hours :-( Any ideas on how to track down my mistake ?

  Here’s a link to the repo. The offending code is in Icosahedron Video Player/mesh.cpp, Mesh::LoadVideo and Mesh::NextFrame().