[FFmpeg-devel] [PATCH 1/3] lavf/f_select: support scenecut with more pixel formats

[Marton Balint]

On Tue, 16 Jul 2019, lance.lmwang at gmail.com wrote:

> From: Limin Wang <lance.lmwang at gmail.com>
>
> This patch haven't make other pixel format usable yet to make sure the test
> result is same with rgb format.
>
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
> libavfilter/f_select.c | 34 ++++++++++++++++++++++++++++++----
> 1 file changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/libavfilter/f_select.c b/libavfilter/f_select.c
> index 1132375..eed8df3 100644
> --- a/libavfilter/f_select.c
> +++ b/libavfilter/f_select.c
> @@ -28,6 +28,8 @@
> #include "libavutil/fifo.h"
> #include "libavutil/internal.h"
> #include "libavutil/opt.h"
> +#include "libavutil/imgutils.h"
> +#include "libavutil/pixdesc.h"
> #include "avfilter.h"
> #include "audio.h"
> #include "formats.h"
> @@ -144,6 +146,10 @@ typedef struct SelectContext {
>     char *expr_str;
>     AVExpr *expr;
>     double var_values[VAR_VARS_NB];
> +    int bitdepth;
> +    int nb_planes;
> +    ptrdiff_t width[4];
> +    ptrdiff_t height[4];
>     int do_scene_detect;            ///< 1 if the expression requires scene detection variables, 0 otherwise
>     ff_scene_sad_fn sad;            ///< Sum of the absolute difference function (scene detect only)
>     double prev_mafd;               ///< previous MAFD                           (scene detect only)
> @@ -202,6 +208,17 @@ static av_cold int init(AVFilterContext *ctx)
> static int config_input(AVFilterLink *inlink)
> {
>     SelectContext *select = inlink->dst->priv;
> +    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
> +
> +    select->bitdepth = desc->comp[0].depth;
> +    select->nb_planes = av_pix_fmt_count_planes(inlink->format);
> +    for (int plane = 0; plane < select->nb_planes; plane++) {
> +        ptrdiff_t line_size = av_image_get_linesize(inlink->format, inlink->w, plane);
> +        int vsub = desc->log2_chroma_h;
> +
> +        select->width[plane] = line_size >> (select->bitdepth > 8);
> +        select->height[plane] = plane == 1 || plane == 2 ?  AV_CEIL_RSHIFT(inlink->h, vsub) : inlink->h;
> +    }
>
>     select->var_values[VAR_N]          = 0.0;
>     select->var_values[VAR_SELECTED_N] = 0.0;
> @@ -242,7 +259,7 @@ static int config_input(AVFilterLink *inlink)
>         inlink->type == AVMEDIA_TYPE_AUDIO ? inlink->sample_rate : NAN;
>
>     if (CONFIG_SELECT_FILTER && select->do_scene_detect) {
> -        select->sad = ff_scene_sad_get_fn(8);
> +        select->sad = ff_scene_sad_get_fn(select->bitdepth == 8 ? 8 : 16);
>         if (!select->sad)
>             return AVERROR(EINVAL);
>     }
> @@ -258,12 +275,21 @@ static double get_scene_score(AVFilterContext *ctx, AVFrame *frame)
>     if (prev_picref &&
>         frame->height == prev_picref->height &&
>         frame->width  == prev_picref->width) {
> -        uint64_t sad;
> +        uint64_t sad = 0;
>         double mafd, diff;
> +        int count = 0;
> +
> +        for (int plane = 0; plane < select->nb_planes; plane++) {
> +            uint64_t plane_sad;
> +            select->sad(prev_picref->data[plane], prev_picref->linesize[plane],
> +                    frame->data[plane], frame->linesize[plane],
> +                    select->width[plane], select->height[plane], &plane_sad);
> +            sad += plane_sad;
> +            count += select->width[plane] * select->height[plane];
> +        }
> 
> -        select->sad(prev_picref->data[0], prev_picref->linesize[0], frame->data[0], frame->linesize[0], frame->width * 3, frame->height, &sad);
>         emms_c();
> -        mafd = (double)sad / (frame->width * 3 * frame->height);
> +        mafd = (double)sad / count;

mafd was in [0..255] before you added >8 bitdepth support. For >8 bit you 
have to normalize it to this range becuase the metric should be bitdepth 
invariant.

Regards,
Marton

>         diff = fabs(mafd - select->prev_mafd);
>         ret  = av_clipf(FFMIN(mafd, diff) / 100., 0, 1);
>         select->prev_mafd = mafd;
> -- 
> 2.6.4
>
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