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• simple ffmpeg API example for converting multiple input images into 1 image using tile filter

  9 août 2014, par Pragnesh Patel

  here is my code.....................
  
  
  
  
  
  AVFilterContext **inputContexts;
  
  AVFilterContext *outputContext;
  
  AVFilterGraph *graph;
  
  
  
  int initFilters(AVFrame *bgFrame, int inputCount, AVCodecContext **codecContexts, char       *filters)
  
  {
  
        int i;
  
    int returnCode;
  
     char args[512];
  
  char name[9];
  
  AVFilterInOut **graphInputs = NULL;
  
  AVFilterInOut *graphOutput = NULL;
  
  
  
  AVFilter *bufferSrc  = avfilter_get_by_name("buffer");
  
  AVFilter *bufferSink = avfilter_get_by_name("buffersink");
  
  
  
  graph = avfilter_graph_alloc();
  
  if(graph == NULL)
  
      return -1;
  
  
  
  //allocate inputs
  
  graphInputs = av_calloc(inputCount + 1, sizeof(AVFilterInOut *));
  
  for(i = 0; i <= inputCount; i++)
  
  {
  
      graphInputs[i] = avfilter_inout_alloc();
  
      if(graphInputs[i] == NULL)
  
          return -1;
  
  }
  
  
  
  //allocate input contexts
  
  inputContexts = av_calloc(inputCount + 1, sizeof(AVFilterContext *));
  
  //first is the background
  
  snprintf(args, sizeof(args), "video_size=%dx%d:pix_fmt=%d:time_base=1/1:pixel_aspect=0",   bgFrame->width, bgFrame->height, bgFrame->format);
  
  returnCode = avfilter_graph_create_filter(&inputContexts[0], bufferSrc, "background",  args, NULL, graph);
  
  if(returnCode < 0)
  
      return returnCode;
  
  graphInputs[0]->filter_ctx = inputContexts[0];
  
  graphInputs[0]->name = av_strdup("background");
  
  graphInputs[0]->next = graphInputs[1];
  
  
  
  //allocate the rest
  
  for(i = 1; i <= inputCount; i++)
  
  {
  
      AVCodecContext *codecCtx = codecContexts[i - 1];
  
      snprintf(args, sizeof(args),    "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  
                  codecCtx->width, codecCtx->height, codecCtx->pix_fmt,
  
                  codecCtx->time_base.num, codecCtx->time_base.den,
  
                  codecCtx->sample_aspect_ratio.num, codecCtx->sample_aspect_ratio.den);
  
      snprintf(name, sizeof(name), "video_%d", i);
  
  
  
      returnCode = avfilter_graph_create_filter(&inputContexts[i], bufferSrc, name, args, NULL, graph);
  
      if(returnCode < 0)
  
          return returnCode;
  
  
  
      graphInputs[i]->filter_ctx = inputContexts[i];
  
      graphInputs[i]->name = av_strdup(name);
  
      graphInputs[i]->pad_idx = 0;
  
      if(i < inputCount)
  
      {
  
          graphInputs[i]->next = graphInputs[i + 1];
  
      }
  
      else
  
      {
  
          graphInputs[i]->next = NULL;
  
      }
  
  }
  
  
  
  //allocate outputs
  
  graphOutput = avfilter_inout_alloc();   
  
  returnCode = avfilter_graph_create_filter(&outputContext, bufferSink, "out", NULL, NULL, graph);
  
  if(returnCode < 0)
  
      return returnCode;
  
  graphOutput->filter_ctx = outputContext;
  
  graphOutput->name = av_strdup("out");
  
  graphOutput->next = NULL;
  
  graphOutput->pad_idx = 0;
  
  
  
  returnCode = avfilter_graph_parse_ptr(graph, filters, graphInputs, &graphOutput, NULL);
  
  if(returnCode < 0)
  
      return returnCode;
  
  
  
  returnCode = avfilter_graph_config(graph, NULL);
  
      return returnCode;
  
  
  
  return 0;
  
  }

  The filters argument of the function is passed on to avfilter_graph_parse_ptr and it can looks like this : [background] scale=512x512 [base] ; [video_1] scale=256x256 [tmp_1] ; [base][tmp_1] tile=1x2 [out]

  The call breaks after the call to avfilter_graph_config with the warning : Output pad "default" with type video of the filter instance "background" of buffer not connected to any destination and the error Invalid argument.

  please help me

  thanks in advance.................

• Time stamped video to time stamped images

  16 mai 2015, par Andrew

  I have a time stamped AVI video file.

  I want to create images from the frames of the video but I need them to also have a time associated with them as well.

  I can create images from the video through FFmpeg using :

  ffmpeg -i video.avi -r 0.1 image_%05.jpeg

  However this images do not have a time embedded. Is it possible to also take the time associated with each frame in the video ?

  My end goal is to sync the time stamp with a GPS track to geotag the images (from the video frames.)

• quickdraw : Skip the empty 512 byte header for images

  11 mai 2015, par Vittorio Giovara

  quickdraw : Skip the empty 512 byte header for images
  Found-by : Carl Eugen Hoyos <cehoyos@ag.or.at>
  

  • [DBH] libavcodec/qdrw.c