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

[Marton Balint]

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.

> 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