[FFmpeg-devel,v3,1/4] avfilter/vf_scenechangedetect: add filter to detect scene change

From: Limin Wang <lance.lmwang@gmail.com>

Signed-off-by: Limin Wang <lance.lmwang@gmail.com>
---
 configure                          |   1 +
 doc/filters.texi                   |  35 +++++
 libavfilter/Makefile               |   1 +
 libavfilter/allfilters.c           |   1 +
 libavfilter/vf_scenechangedetect.c | 220 +++++++++++++++++++++++++++++
 5 files changed, 258 insertions(+)
 create mode 100644 libavfilter/vf_scenechangedetect.c

On 10/8/19, lance.lmwang@gmail.com <lance.lmwang@gmail.com> wrote:
> From: Limin Wang <lance.lmwang@gmail.com>
>
> Signed-off-by: Limin Wang <lance.lmwang@gmail.com>
> ---
>  configure                          |   1 +
>  doc/filters.texi                   |  35 +++++
>  libavfilter/Makefile               |   1 +
>  libavfilter/allfilters.c           |   1 +
>  libavfilter/vf_scenechangedetect.c | 220 +++++++++++++++++++++++++++++

You are supposed to rename this too.

Also every occurrence of scenechangedetect.

>  5 files changed, 258 insertions(+)
>  create mode 100644 libavfilter/vf_scenechangedetect.c
>
> diff --git a/configure b/configure
> index 8413826f9e..909a77b9cf 100755
> --- a/configure
> +++ b/configure
> @@ -3520,6 +3520,7 @@ sab_filter_deps="gpl swscale"
>  scale2ref_filter_deps="swscale"
>  scale_filter_deps="swscale"
>  scale_qsv_filter_deps="libmfx"
> +scenechangedetect_filter_select="scene_sad"
>  select_filter_select="scene_sad"
>  sharpness_vaapi_filter_deps="vaapi"
>  showcqt_filter_deps="avcodec avformat swscale"
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 0e72cce829..4b3eeb1c15 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -15780,6 +15780,41 @@ Set the initial horizontal scrolling position.
> Default is 0. Allowed range is fr
>  Set the initial vertical scrolling position. Default is 0. Allowed range is
> from 0 to 1.
>  @end table
>
> +@anchor{scdet}
> +@section scdet
> +
> +Detect video scene change.
> +
> +This filter sets frame metadata with mafd between frame, the scene score,
> and
> +forward the frame to the next filter, so they can use these metadata to
> detect
> +scene change or others.
> +
> +In addition, this filter logs a message and sets frame metadata when it
> detects
> +a scene change by @option{threshold}.
> +
> +@code{lavfi.scd.mafd} metadata keys are set with mafd for every frame.
> +
> +@code{lavfi.scd.score} metadata keys are set with scene change score for
> every frame
> +to detect scene change.
> +
> +@code{lavfi.scd.time} metadata keys are set with current filtered frame
> time which
> +detect scene change with @option{threshold}.
> +
> +The filter accepts the following options:
> +
> +@table @option
> +@item threshold, t
> +Set the scene change detection threshold as a percentage of maximum change.
> Good
> +values are in the @code{[8.0, 14.0]} range. The range for
> @option{threshold} is
> +@code{[0., 100.]}.
> +
> +Default value is @code{10.}.
> +
> +@item sc_pass, s
> +Set the flag to pass scene change frames to the next filter. Default value
> is @code{0}
> +You can enable it if you want to get snapshot of scene change frames only.
> +@end table
> +
>  @anchor{selectivecolor}
>  @section selectivecolor
>
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 16bb8cd965..75ed533bdb 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -358,6 +358,7 @@ OBJS-$(CONFIG_SCALE_NPP_FILTER)              +=
> vf_scale_npp.o scale.o
>  OBJS-$(CONFIG_SCALE_QSV_FILTER)              += vf_scale_qsv.o
>  OBJS-$(CONFIG_SCALE_VAAPI_FILTER)            += vf_scale_vaapi.o scale.o
> vaapi_vpp.o
>  OBJS-$(CONFIG_SCALE2REF_FILTER)              += vf_scale.o scale.o
> +OBJS-$(CONFIG_SCENECHANGEDETECT_FILTER)      += vf_scenechangedetect.o
>  OBJS-$(CONFIG_SCROLL_FILTER)                 += vf_scroll.o
>  OBJS-$(CONFIG_SELECT_FILTER)                 += f_select.o
>  OBJS-$(CONFIG_SELECTIVECOLOR_FILTER)         += vf_selectivecolor.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 4f8b3039ed..5379fccdfc 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -340,6 +340,7 @@ extern AVFilter ff_vf_scale_npp;
>  extern AVFilter ff_vf_scale_qsv;
>  extern AVFilter ff_vf_scale_vaapi;
>  extern AVFilter ff_vf_scale2ref;
> +extern AVFilter ff_vf_scenechangedetect;
>  extern AVFilter ff_vf_scroll;
>  extern AVFilter ff_vf_select;
>  extern AVFilter ff_vf_selectivecolor;
> diff --git a/libavfilter/vf_scenechangedetect.c
> b/libavfilter/vf_scenechangedetect.c
> new file mode 100644
> index 0000000000..a745ee15b3
> --- /dev/null
> +++ b/libavfilter/vf_scenechangedetect.c
> @@ -0,0 +1,220 @@
> +/*
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
> USA
> + */
> +
> +/**
> + * @file
> + * video scene change detection filter
> + */
> +
> +#include "libavutil/avassert.h"
> +#include "libavutil/imgutils.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/pixdesc.h"
> +#include "libavutil/timestamp.h"
> +
> +#include "avfilter.h"
> +#include "filters.h"
> +#include "scene_sad.h"
> +
> +typedef struct SceneChangeDetectContext {
> +    const AVClass *class;
> +
> +    ptrdiff_t width[4];
> +    ptrdiff_t height[4];
> +    int nb_planes;
> +    int bitdepth;
> +    ff_scene_sad_fn sad;
> +    double prev_mafd;
> +    double scene_score;
> +    AVFrame *prev_picref;
> +    double threshold;
> +    int sc_pass;
> +} SceneChangeDetectContext;
> +
> +#define OFFSET(x) offsetof(SceneChangeDetectContext, x)
> +#define V AV_OPT_FLAG_VIDEO_PARAM
> +#define F AV_OPT_FLAG_FILTERING_PARAM
> +
> +static const AVOption scenechangedetect_options[] = {
> +    { "threshold",   "set scene change detect threshold",
> OFFSET(threshold),  AV_OPT_TYPE_DOUBLE,   {.dbl = 10.},     0,  100., V|F },
> +    { "t",           "set scene change detect threshold",
> OFFSET(threshold),  AV_OPT_TYPE_DOUBLE,   {.dbl = 10.},     0,  100., V|F },
> +    { "sc_pass",     "Set the flag to pass scene change frames",
> OFFSET(sc_pass),    AV_OPT_TYPE_BOOL,     {.dbl =  0  },    0,    1,  V|F },
> +    { "s",           "Set the flag to pass scene change frames",
> OFFSET(sc_pass),    AV_OPT_TYPE_BOOL,     {.dbl =  0  },    0,    1,  V|F },
> +    {NULL}
> +};
> +
> +AVFILTER_DEFINE_CLASS(scenechangedetect);
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> +    static const enum AVPixelFormat pix_fmts[] = {
> +            AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24, AV_PIX_FMT_RGBA,
> +            AV_PIX_FMT_ABGR, AV_PIX_FMT_BGRA, AV_PIX_FMT_GRAY8,
> +            AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUVJ420P,
> +            AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUVJ422P,
> +            AV_PIX_FMT_YUV420P10,
> +            AV_PIX_FMT_NONE
> +    };
> +
> +    AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
> +    if (!fmts_list)
> +        return AVERROR(ENOMEM);
> +    return ff_set_common_formats(ctx, fmts_list);
> +}
> +
> +static int config_input(AVFilterLink *inlink)
> +{
> +    AVFilterContext *ctx = inlink->dst;
> +    SceneChangeDetectContext *s = ctx->priv;
> +    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
> +    int is_yuv = !(desc->flags & AV_PIX_FMT_FLAG_RGB) &&
> +        (desc->flags & AV_PIX_FMT_FLAG_PLANAR) &&
> +        desc->nb_components >= 3;
> +
> +    s->bitdepth = desc->comp[0].depth;
> +    s->nb_planes = is_yuv ? 1 : av_pix_fmt_count_planes(inlink->format);
> +
> +    for (int plane = 0; plane < 4; plane++) {
> +        ptrdiff_t line_size = av_image_get_linesize(inlink->format,
> inlink->w, plane);
> +        s->width[plane] = line_size >> (s->bitdepth > 8);
> +        s->height[plane] = inlink->h >> ((plane == 1 || plane == 2) ?
> desc->log2_chroma_h : 0);
> +    }
> +
> +    s->sad = ff_scene_sad_get_fn(s->bitdepth == 8 ? 8 : 16);
> +    if (!s->sad)
> +        return AVERROR(EINVAL);
> +
> +    return 0;
> +}
> +
> +static av_cold void uninit(AVFilterContext *ctx)
> +{
> +    SceneChangeDetectContext *s = ctx->priv;
> +
> +    av_frame_free(&s->prev_picref);
> +}
> +
> +static double get_scene_score(AVFilterContext *ctx, AVFrame *frame)
> +{
> +    double ret = 0;
> +    SceneChangeDetectContext *s = ctx->priv;
> +    AVFrame *prev_picref = s->prev_picref;
> +
> +    if (prev_picref && frame->height == prev_picref->height
> +                    && frame->width  == prev_picref->width) {
> +        uint64_t sad = 0;
> +        double mafd, diff;
> +        uint64_t count = 0;
> +
> +        for (int plane = 0; plane < s->nb_planes; plane++) {
> +            uint64_t plane_sad;
> +            s->sad(prev_picref->data[plane], prev_picref->linesize[plane],
> +                    frame->data[plane], frame->linesize[plane],
> +                    s->width[plane], s->height[plane], &plane_sad);
> +            sad += plane_sad;
> +            count += s->width[plane] * s->height[plane];
> +        }
> +
> +        emms_c();
> +        mafd = (double)sad * 100. / count / (1ULL << s->bitdepth);
> +        diff = fabs(mafd - s->prev_mafd);
> +        ret  = av_clipf(FFMIN(mafd, diff), 0, 100.);
> +        s->prev_mafd = mafd;
> +        av_frame_free(&prev_picref);
> +    }
> +    s->prev_picref = av_frame_clone(frame);
> +    return ret;
> +}
> +
> +static int set_meta(SceneChangeDetectContext *s, AVFrame *frame, const char
> *key, const char *value)
> +{
> +    return av_dict_set(&frame->metadata, key, value, 0);
> +}
> +
> +static int activate(AVFilterContext *ctx)
> +{
> +    int ret;
> +    AVFilterLink *inlink = ctx->inputs[0];
> +    AVFilterLink *outlink = ctx->outputs[0];
> +    SceneChangeDetectContext *s = ctx->priv;
> +    AVFrame *frame;
> +
> +    FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
> +
> +    ret = ff_inlink_consume_frame(inlink, &frame);
> +    if (ret < 0)
> +        return ret;
> +
> +    if (frame) {
> +        char buf[64];
> +        s->scene_score = get_scene_score(ctx, frame);
> +        snprintf(buf, sizeof(buf), "%0.3f", s->prev_mafd);
> +        set_meta(s, frame, "lavfi.scd.mafd", buf);
> +        snprintf(buf, sizeof(buf), "%0.3f", s->scene_score);
> +        set_meta(s, frame, "lavfi.scd.score", buf);
> +
> +        if (s->scene_score > s->threshold) {
> +            av_log(s, AV_LOG_INFO, "lavfi.scd.score: %.3f, lavfi.scd.time:
> %s\n",
> +                    s->scene_score, av_ts2timestr(frame->pts,
> &inlink->time_base));
> +            set_meta(s, frame, "lavfi.scd.time",
> +                    av_ts2timestr(frame->pts, &inlink->time_base));
> +        }
> +        if (s->sc_pass) {
> +            if (s->scene_score > s->threshold)
> +                return ff_filter_frame(outlink, frame);
> +            else {
> +                av_frame_free(&frame);
> +            }
> +        } else
> +            return ff_filter_frame(outlink, frame);
> +    }
> +
> +    FF_FILTER_FORWARD_STATUS(inlink, outlink);
> +    FF_FILTER_FORWARD_WANTED(outlink, inlink);
> +
> +    return FFERROR_NOT_READY;
> +}
> +
> +static const AVFilterPad scenechangedetect_inputs[] = {
> +    {
> +        .name         = "default",
> +        .type         = AVMEDIA_TYPE_VIDEO,
> +        .config_props = config_input,
> +    },
> +    { NULL }
> +};
> +
> +static const AVFilterPad scenechangedetect_outputs[] = {
> +    {
> +        .name          = "default",
> +        .type          = AVMEDIA_TYPE_VIDEO,
> +    },
> +    { NULL }
> +};
> +
> +AVFilter ff_vf_scenechangedetect = {
> +    .name          = "scdet",
> +    .description   = NULL_IF_CONFIG_SMALL("Detect video scene change"),
> +    .priv_size     = sizeof(SceneChangeDetectContext),
> +    .priv_class    = &scenechangedetect_class,
> +    .uninit        = uninit,
> +    .query_formats = query_formats,
> +    .inputs        = scenechangedetect_inputs,
> +    .outputs       = scenechangedetect_outputs,
> +    .activate      = activate,
> +};
> --
> 2.21.0
>
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