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• Can you force ffmpeg hls demuxing to start from the beginning in a live hls stream ?

  13 octobre 2016, par jdramer

  When remuxing an hls stream into an mp4 file I use the following command.

  ffmpeg -i "http://example.com/master.m3u8" -c copy -bsf:a aac_adtstoasc output.mp4

  This works fine for VOD content, but if the stream is live it starts from the live position, rather than the very first segment in the m3u8 file. Does the applehttp demuxer have any parameters that would force starting from the first segment ?

• Overlay filter in LibAV/FFMpeg returns strange (tripled) frame in C

  28 juillet 2014, par gkuczera

  I tried to make a program, which merges two frames. I use LibAV (libav-win32-20140428) under Windows 7 64 and Visual Studio 2013.
  But the result is quite odd.

  

  The filter which was used is Overlay. When I change the graph, to the one, that uses only one stream and add FADE effect, everything works like a charm. But OVERLAY and eg. DRAWBOX give me strange distortion (three frames on one and black and white effect). Here is the code :

  static int init_filter_graph(AVFilterGraph **pGraph, AVFilterContext **pSrc1, AVFilterContext **pSink)
  
  {
  
      AVFilterGraph* tFilterGraph;
  
      AVFilterContext* tBufferContext1;
  
      AVFilter* tBuffer1;
  
      AVFilterContext* tColorContext;
  
      AVFilter* tColor;
  
      AVFilterContext* tOverlayContext;
  
      AVFilter* tOverlay;
  
      AVFilterContext* tBufferSinkContext;
  
      AVFilter* tBufferSink;
  
  
  
      int tError;
  
  
  
      /* Create a new filtergraph, which will contain all the filters. */
  
      tFilterGraph = avfilter_graph_alloc();
  
  
  
      if (!tFilterGraph) {
  
          return -1;
  
      }
  
  
  
      { // BUFFER FILTER 1
  
          tBuffer1 = avfilter_get_by_name("buffer");
  
          if (!tBuffer1) {
  
              return -1;
  
          }
  
          tBufferContext1 = avfilter_graph_alloc_filter(tFilterGraph, tBuffer1, "src1");
  
          if (!tBufferContext1) {
  
              return -1;
  
          }
  
  
  
          av_dict_set(&tOptionsDict, "width", "320", 0);
  
          av_dict_set(&tOptionsDict, "height", "240", 0);
  
          av_dict_set(&tOptionsDict, "pix_fmt", "bgr24", 0);
  
          av_dict_set(&tOptionsDict, "time_base", "1/25", 0);
  
          av_dict_set(&tOptionsDict, "sar", "1", 0);
  
          tError = avfilter_init_dict(tBufferContext1, &tOptionsDict);
  
          av_dict_free(&tOptionsDict);
  
          if (tError < 0) {
  
              return tError;
  
          }
  
      }
  
  
  
      { // COLOR FILTER
  
          tColor = avfilter_get_by_name("color");
  
          if (!tColor) {
  
              return -1;
  
          }
  
          tColorContext = avfilter_graph_alloc_filter(tFilterGraph, tColor, "color");
  
          if (!tColorContext) {
  
              return -1;
  
          }
  
  
  
          av_dict_set(&tOptionsDict, "color", "white", 0);
  
          av_dict_set(&tOptionsDict, "size", "20x120", 0);
  
          av_dict_set(&tOptionsDict, "framerate", "1/25", 0);
  
          tError = avfilter_init_dict(tColorContext, &tOptionsDict);
  
          av_dict_free(&tOptionsDict);
  
          if (tError < 0) {
  
              return tError;
  
          }
  
      }
  
  
  
      { // OVERLAY FILTER
  
          tOverlay = avfilter_get_by_name("overlay");
  
          if (!tOverlay) {
  
              return -1;
  
          }
  
          tOverlayContext = avfilter_graph_alloc_filter(tFilterGraph, tOverlay, "overlay");
  
          if (!tOverlayContext) {
  
              return -1;
  
          }
  
  
  
          av_dict_set(&tOptionsDict, "x", "0", 0);
  
          av_dict_set(&tOptionsDict, "y", "0", 0);
  
          av_dict_set(&tOptionsDict, "main_w", "120", 0);
  
          av_dict_set(&tOptionsDict, "main_h", "140", 0);
  
          av_dict_set(&tOptionsDict, "overlay_w", "320", 0);
  
          av_dict_set(&tOptionsDict, "overlay_h", "240", 0);
  
          tError = avfilter_init_dict(tOverlayContext, &tOptionsDict);
  
          av_dict_free(&tOptionsDict);
  
          if (tError < 0) {
  
              return tError;
  
          }
  
      }
  
  
  
      { // BUFFERSINK FILTER
  
          tBufferSink = avfilter_get_by_name("buffersink");
  
          if (!tBufferSink) {
  
              return -1;
  
          }
  
  
  
          tBufferSinkContext = avfilter_graph_alloc_filter(tFilterGraph, tBufferSink, "sink");
  
          if (!tBufferSinkContext) {
  
              return -1;
  
          }
  
  
  
          tError = avfilter_init_str(tBufferSinkContext, NULL);
  
          if (tError < 0) {
  
              return tError;
  
          }
  
      }
  
  
  
      // Linking graph
  
      tError = avfilter_link(tBufferContext1, 0, tOverlayContext, 0);
  
      if (tError >= 0) {
  
          tError = avfilter_link(tColorContext, 0, tOverlayContext, 1);
  
      }
  
      if (tError >= 0) {
  
          tError = avfilter_link(tOverlayContext, 0, tBufferSinkContext, 0);
  
      }
  
      if (tError < 0) {
  
          return tError;
  
      }
  
  
  
      tError = avfilter_graph_config(tFilterGraph, NULL);
  
      if (tError < 0) {
  
          return tError;
  
      }
  
  
  
      *pGraph = tFilterGraph;
  
      *pSrc1 = tBufferContext1;
  
      *pSink = tBufferSinkContext;
  
  
  
      return 0;
  
  }

  What do you think is the reason ?

• Live Transcoding & Streaming

  4 mars 2016, par acohen

  My client has a requirement where he needs me to transcode a source file into a proxy with a unique burn in on it per playback.

  For the proxy I will be using ffmpeg, nothing fancy, but ideally the users can play back the file as it is being transcoded since it may take up to several minutes to complete the transcoding.

  Another restriction is that the player does not support HLS and other live streaming options and can only accept MP4s as a source.

  Any ideas/suggestions would be great.