FFprobe closed_captions JSON tag not set

[ptr727]

ffprobe does not identify closed captions when using JSON output mode.

Unformatted output:

./ffprobe.exe D:\Temp\CC.mkv
  Stream #0:0(eng): Video: h264 (High), yuv420p(tv, bt709, progressive), 1920x1080, Closed Captions, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 1k tbn (default)

Note the Closed Captions attribute.

JSON output:

./ffprobe.exe -loglevel quiet -print_format json -show_streams -show_format D:\Temp\CC.mkv
{
    "streams": [
        {
            "index": 0,
            "codec_name": "h264",
            "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
...
            "closed_captions": 0,

Note the closed_captions attribute is 0, expect it to be 1.

Asked for help or alternatives here:
https://www.reddit.com/r/ffmpeg/comments/tcnhto/how_to_detect_closed_captions_in_video_stream/
https://forum.videohelp.com/threads/405123-Detect-embedded-closed-captions-in-video-stream-using-ffprobe-json-output

Discovered an abandoned patch for exactly this issue, seems there was some internal disagreement:
https://patchwork.ffmpeg.org/project/ffmpeg/patch/MN2PR04MB59815313285AA685E37D09AEBAB09@MN2PR04MB5981.namprd04.prod.outlook.com/
https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=&submitter=&state=*&q=closed_captions&archive=both&delegate=
https://www.mail-archive.com/ffmpeg-devel@ffmpeg.org/msg126211.html

diff --git a/fftools/ffprobe.c b/fftools/ffprobe.c
index 90e895bbf9..f5c6335a13 100644
--- a/fftools/ffprobe.c
+++ b/fftools/ffprobe.c
@@ -2655,9 +2655,9 @@  static int show_stream(WriterContext *w, AVFormatContext *fmt_ctx, int stream_id
         if (dec_ctx) {
             print_int("coded_width",  dec_ctx->coded_width);
             print_int("coded_height", dec_ctx->coded_height);
-            print_int("closed_captions", !!(dec_ctx->properties & FF_CODEC_PROPERTY_CLOSED_CAPTIONS));
-            print_int("film_grain", !!(dec_ctx->properties & FF_CODEC_PROPERTY_FILM_GRAIN));
         }
+        print_int("closed_captions", !!(par->properties & FF_CODEC_PROPERTY_CLOSED_CAPTIONS));
+        print_int("film_grain", !!(par->properties & FF_CODEC_PROPERTY_FILM_GRAIN));
         print_int("has_b_frames", par->video_delay);
         sar = av_guess_sample_aspect_ratio(fmt_ctx, stream, NULL);
         if (sar.num) {

Source related to closed_captions setting:
https://github.com/FFmpeg/FFmpeg/blob/b8e58f0858116ac102fc116ce1bdf6727df1eb0c/libavcodec/avcodec.c#L650
https://github.com/FFmpeg/FFmpeg/blob/316e0ff752c782439843cc63d0eb8b9c998e47de/fftools/ffprobe.c#L2902

My request to the ffmpeg-devel list to reconsider:
https://www.mail-archive.com/ffmpeg-devel@ffmpeg.org/msg133559.html

[ptr727]

Abandoning, see #497.

[bbgdzxng1]

@ptr727 did you ever solve to your satisfaction?

I saw your cross referenced requests on various forums (reddit & ccextractor) and I think you may just have been missing the -analyze_frames option.

-analyze_frames

Analyze frames and/or their side data up to the provided read interval, providing additional information that may be useful at a stream level. Must be paired with the -show_streams option or it will have no effect.

Currently, the additional fields provided by this option when enabled are the closed_captions and film_grain fields. 

$ ffprobe -hide_banner -loglevel 'quiet' -show_entries 'stream=closed_captions' -analyze_frames -print_format 'json' "http://streams.videolan.org/streams/ts/CC/NewsStream-608-ac3.ts" | jq -r '.streams[0].closed_captions'
1

$ ffprobe -hide_banner -loglevel 'quiet' -show_entries 'stream=closed_captions' -analyze_frames -print_format 'json' "http://streams.videolan.org/streams/ts/CC/NewsStream-608-ac3.ts"

{
    "programs": [
        {
            "streams": [
                {
                    "closed_captions": 1,
                    "side_data_list": [
                        {

                        }
                    ]
                },
                {

                }
            ]
        }
    ],
    "stream_groups": [

    ],
    "streams": [
        {
            "closed_captions": 1,
            "side_data_list": [
                {

                }
            ]
        },
        {

        }
    ]
}

Hope this helps you without needing a code change in FFmpeg.

[ptr727]

did you ever solve to your satisfaction?

There is a comment about this in the readme, I have not retested recently, but when I tested this it was not yet released.