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• Need help using libavfilter for adding overlay to frames [closed]

  30 juillet 2024, par Michael Werner

  Hello gentlemen and ladies,

  


  I am working with libavfilter and I am getting crazy.

  


  On Windows 11 OS with latest libav (full build) a C/C++ app reads YUV420P frames from a frame grabber card.

  


  I want to draw a 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) return code, independent on how many frames I put into the graph.

  


  The frames from the frame grabber card are fine, I could encode them or write them to a .yuv file. The overlay frame looks fine too.

  


  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;
}


  


  Feeding the filter graph is done this way :

  


  av_buffersrc_add_frame_flags(buffersrc_ctx, pFrameGrabberFrame, AV_BUFFERSRC_FLAG_KEEP_REF)
av_buffersink_get_frame(buffersink_ctx, filtered_frame)


  


  av_buffersink_get_frame returns always EAGAIN, no matter how many frames I feed into the graph. The frames (from framegrabber and the overlay frame) itself are looking fine.

  


  I did set libav logging level to maximum but I do not see any warnings or errors or helpful, related information in the log.

  


  Here the log output related to the filter configuration :

  


  [in @ 00000288ee494f40] Setting 'video_size' to value '1920x1080'
[in @ 00000288ee494f40] Setting 'pix_fmt' to value 'yuv420p'
[in @ 00000288ee494f40] Setting 'time_base' to value '1/25'
[in @ 00000288ee494f40] Setting 'pixel_aspect' to value '1/1'
[in @ 00000288ee494f40] w:1920 h:1080 pixfmt:yuv420p tb:1/25 fr:0/1 sar:1/1 csp:unknown range:unknown
[overlay_in @ 00000288ff1013c0] Setting 'video_size' to value '165x165'
[overlay_in @ 00000288ff1013c0] Setting 'pix_fmt' to value 'bgr24'
[overlay_in @ 00000288ff1013c0] Setting 'time_base' to value '1/25'
[overlay_in @ 00000288ff1013c0] Setting 'pixel_aspect' to value '1/1'
[overlay_in @ 00000288ff1013c0] w:165 h:165 pixfmt:bgr24 tb:1/25 fr:0/1 sar:1/1 csp:unknown range:unknown
[format @ 00000288ff1015c0] Setting 'pix_fmts' to value 'yuv420p'
[overlay @ 00000288ff101880] Setting 'x' to value 'W-w'
[overlay @ 00000288ff101880] Setting 'y' to value 'H-h'
[overlay @ 00000288ff101880] Setting 'enable' to value 'between(t,0,20)'
[overlay @ 00000288ff101880] Setting 'format' to value 'yuv420'
[auto_scale_0 @ 00000288ff101ec0] w:iw h:ih flags:'' interl:0
[format @ 00000288ff1015c0] auto-inserting filter 'auto_scale_0' between the filter 'overlay_in' and the filter 'format'
[auto_scale_1 @ 00000288ee4a4cc0] w:iw h:ih flags:'' interl:0
[overlay @ 00000288ff101880] auto-inserting filter 'auto_scale_1' between the filter 'format' and the filter 'overlay'
[AVFilterGraph @ 00000288ee495c80] query_formats: 5 queried, 6 merged, 6 already done, 0 delayed
[auto_scale_0 @ 00000288ff101ec0] w:165 h:165 fmt:bgr24 csp:gbr range:pc sar:1/1 -> w:165 h:165 fmt:yuv420p csp:unknown range:unknown sar:1/1 flags:0x00000004
[auto_scale_1 @ 00000288ee4a4cc0] w:165 h:165 fmt:yuv420p csp:unknown range:unknown sar:1/1 -> w:165 h:165 fmt:yuva420p csp:unknown range:unknown sar:1/1 flags:0x00000004
[overlay @ 00000288ff101880] main w:1920 h:1080 fmt:yuv420p overlay w:165 h:165 fmt:yuva420p
[overlay @ 00000288ff101880] [framesync @ 00000288ff1019a8] Selected 1/25 time base
[overlay @ 00000288ff101880] [framesync @ 00000288ff1019a8] Sync level 2


  


• ffmpeg - Stream webcam - RTP h264 + audio

  17 mai 2016, par Hossein

  I am trying to create a rtp stream using ffmpeg. I am taking input from my logitech C920 which has built in h264 encoding support and also has a microphone. I wanted to send both video(h264 either with the built in encoder or ffmpeg’s encoder) and audio(any encoding) through RTP and then play the stream using ffplay.

  So far I am able to send only the video with the following command :

  ffmpeg -i /dev/video0 -r 24 -video_size 320x240 -c:v libx264 -f  rtp rtp://127.0.0.1:9999

  and also the audio separately using the command :

  ffmpeg  -f alsa -i plughw:CARD=C920,DEV=0 -acodec libmp3lame -t 20 -f  rtp rtp://127.0.0.1:9998

  and play the sdp file with :

   ffplay -i -protocol_whitelist file,udp,rtp test3.sdp 
  
   ffplay -i -protocol_whitelist file,udp,rtp test4.sdp 

  I’m on Ubuntu 14.04

  How can I play the two streams with a single ffplay command as ffplay cannot take two inputs and I can’t send two streams using a single RTP stream(or can I ?).
  Also, how can I use the built in h264 encoder of my webcam ?

  Thank you !

• after 10M ffmpeg stops saving video on nodejs

  12 mai 2016, par cauchy

  I have a nodejs server running using express (express 4). I want to save the video from a few IP cameras on a lab on request. Everything works, but if the video is too long it doesn’t get saved (the limit seems to be 11M).

  I tried using only the command line :

  ffmpeg -i rtsp://192.168.1.189:554/ch01_sub.264 -strict -2 -vcodec
  
  copy -vcodec copy test.mp4

  and this works. But I get into trouble as soon as I use node (note that this is in the node parser, no code in express. I get the same error when running the server) :

  var child_process = require('child_process');
  
  tmpProcess = child_process.spawn('ffmpeg',['-i','rtsp://192.168.1.189:554/ch01_sub.264','-strict','-2','-vcodec','copy','-vcodec','copy',"test.mp4"],{maxBuffer: 10000});

  this runs until test.mp4 is around 11M. tmpProcess is not killed, it keeps running. But after test.mp4 is of certain size I cannot play it back. I get an error saying that "This file contains no playable streams." (this is from Totem, but VLC doesn’t work either).

  Changing maxBuffer doesn’t help. I’m trying to understand what buffer am I overflooding but I cannot get much info from the manual on the api of node.