[FFmpeg-devel] [PATCH 1/2] avfilter/vf_blackdetect: support full-range YUV

[Niklas Haas]

Any objections to these two patches?

On Fri, 09 Dec 2022 01:28:05 +0100 Niklas Haas <ffmpeg at haasn.xyz> wrote:
> From: Niklas Haas <git at haasn.dev>
> 
> This filter currently makes the distinction between limited and full
> range by testing for the deprecated YUVJ pixel formats at link setup
> time. This is deprecated and should be improved to perform the detection
> based on the per-frame metadata.
> 
> Rewrite it to calculate the black pixel threshold at the time of
> filtering a frame, when metadata about the frame's color range is known.
> Doing it this way has the small side benefit of being able to handle
> streams with variable metadata, and is not a meaningful performance
> cost.
> 
> Signed-off-by: Niklas Haas <git at haasn.dev>
> ---
>  libavfilter/vf_blackdetect.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/libavfilter/vf_blackdetect.c b/libavfilter/vf_blackdetect.c
> index 99ff1ac606..c937248169 100644
> --- a/libavfilter/vf_blackdetect.c
> +++ b/libavfilter/vf_blackdetect.c
> @@ -102,8 +102,6 @@ static int config_input(AVFilterLink *inlink)
>      BlackDetectContext *s = ctx->priv;
>      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
>      const int depth = desc->comp[0].depth;
> -    const int max = (1 << depth) - 1;
> -    const int factor = (1 << (depth - 8));
>  
>      s->depth = depth;
>      s->nb_threads = ff_filter_get_nb_threads(ctx);
> @@ -113,16 +111,10 @@ static int config_input(AVFilterLink *inlink)
>      if (!s->counter)
>          return AVERROR(ENOMEM);
>  
> -    s->pixel_black_th_i = ff_fmt_is_in(inlink->format, yuvj_formats) ?
> -        // luminance_minimum_value + pixel_black_th * luminance_range_size
> -             s->pixel_black_th *  max :
> -        16 * factor + s->pixel_black_th * (235 - 16) * factor;
> -
>      av_log(s, AV_LOG_VERBOSE,
> -           "black_min_duration:%s pixel_black_th:%f pixel_black_th_i:%d picture_black_ratio_th:%f\n",
> +           "black_min_duration:%s pixel_black_th:%f picture_black_ratio_th:%f\n",
>             av_ts2timestr(s->black_min_duration, &s->time_base),
> -           s->pixel_black_th, s->pixel_black_th_i,
> -           s->picture_black_ratio_th);
> +           s->pixel_black_th, s->picture_black_ratio_th);
>      return 0;
>  }
>  
> @@ -182,6 +174,14 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *picref)
>      AVFilterContext *ctx = inlink->dst;
>      BlackDetectContext *s = ctx->priv;
>      double picture_black_ratio = 0;
> +    const int max = (1 << s->depth) - 1;
> +    const int factor = (1 << (s->depth - 8));
> +    const int full = picref->color_range == AVCOL_RANGE_JPEG ||
> +                     ff_fmt_is_in(picref->format, yuvj_formats);
> +
> +    s->pixel_black_th_i = full ? s->pixel_black_th * max :
> +        // luminance_minimum_value + pixel_black_th * luminance_range_size
> +        16 * factor + s->pixel_black_th * (235 - 16) * factor;
>  
>      ff_filter_execute(ctx, black_counter, picref, NULL,
>                        FFMIN(inlink->h, s->nb_threads));
> -- 
> 2.38.1
>