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• FFmpeg : concatenation problems

  13 décembre 2016, par CryGuy

  I’d like to concat two mpeg files. Both have an MP2 audio stream that I select, but even though copying is intended, an AC3 stream is written.

  Input files :

  Input #0, mpeg, from 'D:\a.mpg':
  
    Duration: 01:25:54.05, start: 0.500000, bitrate: 4528 kb/s
  
      Stream #0:0[0x1bf]: Data: dvd_nav_packet
  
      Stream #0:1[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16p, 192 kb/s
  
      Stream #0:2[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 384 kb/s
  
      Stream #0:3[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, top first), 720x576 [SAR 64:45 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
  
  Input #1, mpeg, from 'D:\b.mpg':
  
    Duration: 00:12:53.11, start: 0.500000, bitrate: 4486 kb/s
  
      Stream #1:0[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16p, 192 kb/s
  
      Stream #1:1[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 384 kb/s
  
      Stream #1:2[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, top first), 720x576 [SAR 64:45 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 

  ffmpeg args :

  -i "d:\a.mpg" -i "d:\b.mpg" -filter_complex "[0:3][0:1][1:2][1:0]concat=n=2:v=1:a=1[v][a]" -map [v] -map [a] -c copy -target pal-dvd "d:\c.mpg"

  As you can see, I selecting the video and the mp2 stream for both input files.

  Output :

  Stream mapping:
  
    Stream #0:1 (mp2) -> concat:in0:a0
  
    Stream #0:3 (mpeg2video) -> concat:in0:v0
  
    Stream #1:0 (mp2) -> concat:in1:a0
  
    Stream #1:2 (mpeg2video) -> concat:in1:v0
  
    concat:out:v0 -> Stream #0:0 (mpeg2video)
  
    concat:out:a0 -> Stream #0:1 (ac3)

  1. As you can see in the last line, the concat filter outputs an AC3 stream. Why ?
  2. The input is interlaced material. In the output file, the interlaced flag is not set correctly so that it’s played back interlaced.

  I’ve been trying to solve this for a couple of hours now, with and without different mapping options.

  Thanks for reading.

• Problems cropping videos with ffmpeg -ss -t

  8 décembre 2016, par Alex Bollbach

  I have been trying to figure out how to precisely crop out sub-sections of a video final.mp4, for example a cropped video with range [0.2, 0.28] or [9.1, 10.2]. So I’ve been using ffmpeg with -ss and -t options. The following command (or some similar form) is what I’ve seen prescribed :

  ffmpeg -y -i final.mp4 -ss 00:00:01 -t 00:00:01.5 -acodec copy -vcodec copy crop1.mp4

  What I expect is a cropped video of length 1.5 starting at time 1.0, but I get a broken video that doesn’t play. Or I’ll try :

  ffmpeg -y -i final.mp4 -ss 1 -c copy -t 1.5 crop1.mp4

  and get a video with the audio cropped to 1.5 seconds but the video lasting much longer freeze framed.

  The point is this should be a relatively straightforward operation but I’m running into problems at every turn. What is wrong with these commands ? My original video is a 7 minute youtube ripped mp4 which I trimmed down to 10 seconds (this seemed to work). But now further finer-grain trimming of that video is showing confusing behavior. Perhaps my video file is somehow in a bad state from the first trimming ?

• Problems using libavfilter for adding overlay to frames

  12 novembre 2024, par Michael Werner

  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