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• Up-to-date example for libavfilter usage [closed]

  25 juillet 2024, par Michael Werner

  I am looking for an example how to use the latest FFmpeg libavfilter functions to add a bitmap overlay image to a video. I only find more than ten years old examples which are based on an old versions of libavfilter.

  


  What I am trying to do :
On Windows with latest libav (full build) an C++ app reads YUV420P frames from a frame grabber card. I want to draw a Windows bitmap BGR24 overlay image (from file) on every frame via libavfilter. First I convert the BGR24 overlay image via format filter to YUV420P. Then I feed the YUV420P frame from frame grabber and the YUV420P overlay into the overlay filter. Everything seems to be fine but when I try to get the frame out of the filter graph I always get an "Resource is temporary not available" (EAGAIN) error, independent on how many frames I put into the graph.

  


  My current initialization code looks like below. It does not report any errors or warnings but when I try to get the filtered frame out of the graph via av_buffersink_get_frame I always get an EAGAIN return code.

  


  Here is my current initialization code :

  


  int init_overlay_filter(AVFilterGraph** graph, AVFilterContext** src_ctx, AVFilterContext** overlay_src_ctx,
                        AVFilterContext** sink_ctx)
{
    AVFilterGraph* filter_graph;
    AVFilterContext* buffersrc_ctx;
    AVFilterContext* overlay_buffersrc_ctx;
    AVFilterContext* buffersink_ctx;
    AVFilterContext* overlay_ctx;
    AVFilterContext* format_ctx;
    const AVFilter *buffersrc, *buffersink, *overlay_buffersrc, *overlay_filter, *format_filter;
    int ret;

    // Create the filter graph
    filter_graph = avfilter_graph_alloc();
    if (!filter_graph)
    {
        fprintf(stderr, "Unable to create filter graph.\n");
        return AVERROR(ENOMEM);
    }

    // Create buffer source filter for main video
    buffersrc = avfilter_get_by_name("buffer");
    if (!buffersrc)
    {
        fprintf(stderr, "Unable to find buffer filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Create buffer source filter for overlay image
    overlay_buffersrc = avfilter_get_by_name("buffer");
    if (!overlay_buffersrc)
    {
        fprintf(stderr, "Unable to find buffer filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Create buffer sink filter
    buffersink = avfilter_get_by_name("buffersink");
    if (!buffersink)
    {
        fprintf(stderr, "Unable to find buffersink filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Create overlay filter
    overlay_filter = avfilter_get_by_name("overlay");
    if (!overlay_filter)
    {
        fprintf(stderr, "Unable to find overlay filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Create format filter
    format_filter = avfilter_get_by_name("format");
    if (!format_filter) 
    {
        fprintf(stderr, "Unable to find format filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Initialize the main video buffer source
    char args[512];
    snprintf(args, sizeof(args),
             "video_size=1920x1080:pix_fmt=yuv420p:time_base=1/25:pixel_aspect=1/1");
    ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in", args, NULL, filter_graph);
    if (ret < 0)
    {
        fprintf(stderr, "Unable to create buffer source filter for main video.\n");
        return ret;
    }

    // Initialize the overlay buffer source
    snprintf(args, sizeof(args),
             "video_size=165x165:pix_fmt=bgr24:time_base=1/25:pixel_aspect=1/1");
    ret = avfilter_graph_create_filter(&overlay_buffersrc_ctx, overlay_buffersrc, "overlay_in", args, NULL,
                                       filter_graph);
    if (ret < 0)
    {
        fprintf(stderr, "Unable to create buffer source filter for overlay.\n");
        return ret;
    }

    // Initialize the format filter to convert overlay image to yuv420p
    snprintf(args, sizeof(args), "pix_fmts=yuv420p");
    ret = avfilter_graph_create_filter(&format_ctx, format_filter, "format", args, NULL, filter_graph);

    if (ret < 0) 
    {
        fprintf(stderr, "Unable to create format filter.\n");
        return ret;
    }

    // Initialize the buffer sink
    ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out", NULL, NULL, filter_graph);
    if (ret < 0)
    {
        fprintf(stderr, "Unable to create buffer sink filter.\n");
        return ret;
    }

    // Initialize the overlay filter
    ret = avfilter_graph_create_filter(&overlay_ctx, overlay_filter, "overlay", "W-w:H-h:enable='between(t,0,20)':format=yuv420", NULL, filter_graph);
    if (ret < 0)
    {
        fprintf(stderr, "Unable to create overlay filter.\n");
        return ret;
    }

    // Connect the filters
    ret = avfilter_link(overlay_buffersrc_ctx, 0, format_ctx, 0);

    if (ret >= 0)
    {
        ret = avfilter_link(buffersrc_ctx, 0, overlay_ctx, 0);
    }
    else
    {
        fprintf(stderr, "Unable to configure filter graph.\n");
        return ret;
    }


    if (ret >= 0) 
    {
        ret = avfilter_link(format_ctx, 0, overlay_ctx, 1);
    }
    else
    {
        fprintf(stderr, "Unable to configure filter graph.\n");
        return ret;
    }

    if (ret >= 0) 
    {
        if ((ret = avfilter_link(overlay_ctx, 0, buffersink_ctx, 0)) < 0)
        {
            fprintf(stderr, "Unable to link filter graph.\n");
            return ret;
        }
    }
    else
    {
        fprintf(stderr, "Unable to configure filter graph.\n");
        return ret;
    }

    // Configure the filter graph
    if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
    {
        fprintf(stderr, "Unable to configure filter graph.\n");
        return ret;
    }

    *graph = filter_graph;
    *src_ctx = buffersrc_ctx;
    *overlay_src_ctx = overlay_buffersrc_ctx;
    *sink_ctx = buffersink_ctx;

    return 0;
}


  


• avformat/avisynth : remove atexit() handler

  7 juillet 2024, par Stephen Hutchinson

  avformat/avisynth : remove atexit() handler
  The atexit() handler in the avisynth demuxer was added because
  
  there was a conflict in AvxSynth that arose due to their use
  
  of C++ global objects, particularly in relation to having
  
  added a logging function relying on log4cpp.
  This conflict was responsible for causing a segfault on exit.
  
  It did not affect Windows with the (at the time) upstream
  
  AviSynth 2.5 and 2.6, nor does it affect AviSynth+.
  Unfortunately, none of this was actually shielded by ifdefs
  
  indicating the fact it was only needed for AvxSynth, so four
  
  years ago when AviSynth+ replaced AvxSynth as the handler
  
  for AviSynth scripts on Unix-like OSes, the fact that the
  
  atexit handler was no longer necessary was overlooked.
  Signed-off-by : Stephen Hutchinson <qyot27@gmail.com>
  

  • [DH] libavformat/avisynth.c

• configure : drop yasm support

  3 octobre 2024, par Lynne

  configure : drop yasm support
  We started defauling to nasm 8 years ago.
  
  We are still compatible with yasm 0.8.0, released in 2009. **15 years ago**.
  
  The time has more than come to remove support for it.
  Maintaining compatibility started cutting into writing new code long ago.
  
  We still can't have 2-argument instructions, preprocessor booleans, and all
  
  AVX2 code must still be wrapped in ifdefs. Newly added code often breaks this.
  

  • [DH] Changelog
  • [DH] configure
  • [DH] doc/developer.texi
  • [DH] doc/optimization.txt
  • [DH] doc/platform.texi