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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 ?

• FFMPEG - Can't create a video from series of images with RGB24 pixel format

  21 juillet 2016, par DevNull

  Goal

  ---

  I’m writing a small proof-of-concept application to take some raw image data I acquire from a digital camera (a series of RGB24 images), and combine them together into a simple, no-audio, video file.

  ---

  Work So Far

  The initialization code is as follows :

  ---

  AVCodec* pCodec = NULL;
  
  AVCodecContext* pCodecContext = NULL;
  
  AVFrame* pFrame = NULL;
  
  
  
  /* Register all available codecs. */
  
  avcodec_register_all();
  
  
  
  /* Determine if desired video encoder is installed. */
  
  pCodec = avcodec_find_encoder(CODEC_ID_MJPEG);
  
  if (!pCodec) {
  
      printf("Codec not installed!\n");
  
  }
  
  
  
  pCodecContext = avcodec_alloc_context3(pCodec);
  
  pFrame = avcodec_alloc_frame();

  ---

  Very cut-and-dry. However, when I try to register the codec, it fails with my custom error message, and one dropped in a nice color-coded format directly from the FFMPEG libraries :

  ---

  [mjpeg @ 0x650d00] Specified pixel format rgb24 is invalid or not supported
  
  Codec not available.

  ---

  I can confirm that that pixel format is valid easily enough :

  ---

  Pixel formats:
  
  I.... = Supported Input  format for conversion
  
  .O... = Supported Output format for conversion
  
  ..H.. = Hardware accelerated format
  
  ...P. = Paletted format
  
  ....B = Bitstream format
  
  
  
  2>&1 ffmpeg -pix_fmts | grep -i -e rgb24 -e flags
  
  FLAGS NAME            NB_COMPONENTS BITS_PER_PIXEL
  
  IO... rgb24                  3            24

  ---

  I can also confirm that the video codec I’m trying to use is valid for encoding.

  ---

  Codecs:
  
   D..... = Decoding supported
  
   .E.... = Encoding supported
  
   ..V... = Video codec
  
   ..A... = Audio codec
  
   ..S... = Subtitle codec
  
   ...I.. = Intra frame-only codec
  
   ....L. = Lossy compression
  
   .....S = Lossless compression
  
  
  
  2>&1 ffmpeg -codecs | grep -i mjpeg              
  
   DEVIL. mjpeg                Motion JPEG

  ---

  Question

  ---

  Why is this pixel format not supported ? It seems like such a common one when working with other utilities like MATLAB, OpenCV, FreeImage, etc. Is there any set of options or functions in FFMPEG/AVcodec that can resolve this issue ? I’d like to avoid having to to manually convert my image to a different color-space if possible, so I’m not burning up CPU cycles by first converting the RGB24 image to a new format, THEN encoding a video frame with it.

  Thank you.

• h264 : fix decoding multiple fields per packet with slice threads

  12 juin 2016, par Anton Khirnov

  h264 : fix decoding multiple fields per packet with slice threads
  Since we only know whether a NAL unit corresponds to a new field after
  
  parsing the slice header, this requires reorganizing the calls to slice
  
  parsing, per-slice/field/frame init and actual decoding.
  In the previous code, the function for slice header decoding also
  
  immediately started a new field/frame as necessary, so any slices
  
  already queued for decoding would no longer be decodable.
  After this patch, we first parse the slice header, and if we determine
  
  that a new field needs to be started we decode all the queued slices.
  

  • [DBH] libavcodec/h264_slice.c
  • [DBH] libavcodec/h264dec.c
  • [DBH] libavcodec/h264dec.h