[FFmpeg-devel] [PATCH v2 1/3] lavf/f_select: support scenecut with more pixel formats

[Limin Wang]

On Sat, Jul 20, 2019 at 09:36:37PM +0200, Marton Balint wrote:
> 
> 
> On Sat, 20 Jul 2019, Limin Wang wrote:
> 
> >On Fri, Jul 19, 2019 at 09:26:06PM +0200, Marton Balint wrote:
> >>
> >>
> >>On Fri, 19 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 rgb32 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 1132375758..eed8df34cb 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;
> >>
> >>Still missing normalization to [0..255] here for >8 bitdepth.
> >By the testing, Passengers_Breakfast_4K.mkv is 10bits sample, it can't detect the scenecut if using 1<<bitdepth,
> 
> You should divide by (1 << (bitdepth - 8)), since you should be
> normalizing to 0..255 here.
> 
Yes, Now I have check the result, it's expected. I have updated the patch. 

> >Or just remove yuv420p10 support, it's the only 10bit enable pixel format in the 3/3 patch?
> >After get more sample for testing it's OK, then change for bitdepth > 8
> 
> You should get the same scores for 10bit and 8bit. (e.g. YUV420P and
> YUV420P10).
> 
> Regards,
> Marton
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