[FFmpeg-devel] [FFmpeg-cvslog] avfilter/framesync: add a new option to set how to sync streams based on secondary input timestamps

[Gyan Doshi]

On 2022-08-10 05:46 pm, James Almer wrote:
> ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Tue Aug  2 08:28:48 2022 -0300| [0c3e3fd1b478e14692f3b02bb8bf42262ee18af0] | committer: James Almer
>
> avfilter/framesync: add a new option to set how to sync streams based on secondary input timestamps

Needs doc entry in filters.texi

http://www.ffmpeg.org/ffmpeg-filters.html#Options-for-filters-with-several-inputs-_0028framesync_0029

Regards,
Gyan


>
> Include two values for it, a default one that sets/keeps the current behavior,
> where the frame event generated by the primary input will have a timestamp
> equal or higher than frames in secondary input, plus a new one where the
> secondary input frame will be that with the absolute closest timestamp to that
> of the frame event one.
>
> Addresses ticket #9689, where the new optional behavior produces better frame
> syncronization.
>
> Reviewed-by: Nicolas George <george at nsup.org>
> Signed-off-by: James Almer <jamrial at gmail.com>
>
>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=0c3e3fd1b478e14692f3b02bb8bf42262ee18af0
> ---
>
>   libavfilter/framesync.c | 19 +++++++++++++++++++
>   libavfilter/framesync.h | 23 +++++++++++++++++++++++
>   2 files changed, 42 insertions(+)
>
> diff --git a/libavfilter/framesync.c b/libavfilter/framesync.c
> index 7510550d8e..ee91e4cf68 100644
> --- a/libavfilter/framesync.c
> +++ b/libavfilter/framesync.c
> @@ -42,6 +42,13 @@ static const AVOption framesync_options[] = {
>           { "pass",   "Pass through the main input.", 0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_PASS },   .flags = FLAGS, "eof_action" },
>       { "shortest", "force termination when the shortest input terminates", OFFSET(opt_shortest), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
>       { "repeatlast", "extend last frame of secondary streams beyond EOF", OFFSET(opt_repeatlast), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
> +    { "ts_sync_mode", "How strictly to sync streams based on secondary input timestamps",
> +        OFFSET(opt_ts_sync_mode), AV_OPT_TYPE_INT, { .i64 = TS_DEFAULT },
> +        TS_DEFAULT, TS_NEAREST, .flags = FLAGS, "ts_sync_mode" },
> +        { "default", "Frame from secondary input with the nearest lower or equal timestamp to the primary input frame",
> +            0, AV_OPT_TYPE_CONST, { .i64 = TS_DEFAULT }, .flags = FLAGS, "ts_sync_mode" },
> +        { "nearest", "Frame from secondary input with the absolute nearest timestamp to the primary input frame",
> +            0, AV_OPT_TYPE_CONST, { .i64 = TS_NEAREST }, .flags = FLAGS, "ts_sync_mode" },
>       { NULL }
>   };
>   static const AVClass framesync_class = {
> @@ -110,6 +117,14 @@ static void framesync_sync_level_update(FFFrameSync *fs)
>       av_assert0(level <= fs->sync_level);
>       if (level < fs->sync_level)
>           av_log(fs, AV_LOG_VERBOSE, "Sync level %u\n", level);
> +    if (fs->opt_ts_sync_mode > TS_DEFAULT) {
> +        for (i = 0; i < fs->nb_in; i++) {
> +            if (fs->in[i].sync < level)
> +                fs->in[i].ts_mode = fs->opt_ts_sync_mode;
> +            else
> +                fs->in[i].ts_mode = TS_DEFAULT;
> +        }
> +    }
>       if (level)
>           fs->sync_level = level;
>       else
> @@ -187,6 +202,10 @@ static int framesync_advance(FFFrameSync *fs)
>           }
>           for (i = 0; i < fs->nb_in; i++) {
>               if (fs->in[i].pts_next == pts ||
> +                (fs->in[i].ts_mode == TS_NEAREST &&
> +                 fs->in[i].have_next &&
> +                 fs->in[i].pts_next != INT64_MAX && fs->in[i].pts != AV_NOPTS_VALUE &&
> +                 fs->in[i].pts_next - pts < pts - fs->in[i].pts) ||
>                   (fs->in[i].before == EXT_INFINITY &&
>                    fs->in[i].state == STATE_BOF)) {
>                   av_frame_free(&fs->in[i].frame);
> diff --git a/libavfilter/framesync.h b/libavfilter/framesync.h
> index a246d2d1e5..233f50a0eb 100644
> --- a/libavfilter/framesync.h
> +++ b/libavfilter/framesync.h
> @@ -75,6 +75,27 @@ enum FFFrameSyncExtMode {
>       EXT_INFINITY,
>   };
>   
> +/**
> + * Timestamp syncronization mode
> + *
> + * Describe how the frames of a stream are syncronized based on timestamp
> + * distance.
> + */
> +enum FFFrameTSSyncMode {
> +
> +    /**
> +     * Sync to frames from secondary input with the nearest, lower or equal
> +     * timestamp to the frame event one.
> +     */
> +    TS_DEFAULT,
> +
> +    /**
> +     * Sync to frames from secondary input with the absolute nearest timestamp
> +     * to the frame event one.
> +     */
> +    TS_NEAREST,
> +};
> +
>   /**
>    * Input stream structure
>    */
> @@ -138,6 +159,7 @@ typedef struct FFFrameSyncIn {
>        */
>       unsigned sync;
>   
> +    enum FFFrameTSSyncMode ts_mode;
>   } FFFrameSyncIn;
>   
>   /**
> @@ -205,6 +227,7 @@ typedef struct FFFrameSync {
>       int opt_repeatlast;
>       int opt_shortest;
>       int opt_eof_action;
> +    int opt_ts_sync_mode;
>   
>   } FFFrameSync;
>   
>
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