[FFmpeg-devel] [PATCH v2 1/3] avfilter/vf_scenechangedetect: add filter to detect scene change

Paul B Mahol onemda at gmail.com
Mon Oct 7 22:00:10 EEST 2019


Too long filter name.

On 10/7/19, Limin Wang <lance.lmwang at gmail.com> wrote:
>
> ping, please give comments.
>
> On Sun, Sep 29, 2019 at 09:25:12PM +0800, lance.lmwang at gmail.com wrote:
>> From: Limin Wang <lance.lmwang at gmail.com>
>>
>> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
>> ---
>> Please provide a comment to add a new filter for scene change detection to
>> avoid
>> multiple calculations of mafd in the filter chain. The filter can avoid
>> duplication
>> code also for I am writing a new filter to synchronize frames that require
>> scene
>> change information. If the detect metadata can get, the code will be
>> simple.
>>
>> In addition, I'm trying  to add a reduced size before scene change
>> detection to improve
>> the performance. From the initial test, we can only get 10-20%
>> improvement, but some
>> scene change aren't detected after that. Therefore, I think that should
>> not be done.
>>
>> This version, I removed the version change for it's easy to cause code
>> conflict,
>> please the committer help to update it if review done.
>>
>>  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
>>
>> 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 e6f8bf0ee9..f9247643cb 100644
>> --- a/doc/filters.texi
>> +++ b/doc/filters.texi
>> @@ -15642,6 +15642,41 @@ Scale a logo to 1/10th the height of a video,
>> while preserving its display aspec
>>  @end example
>>  @end itemize
>>
>> + at anchor{scenechangedetect}
>> + at section scenechangedetect
>> +
>> +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}.
>> +
>> + at code{lavfi.scd.mafd} metadata keys are set with mafd for every frame.
>> +
>> + at code{lavfi.scd.score} metadata keys are set with scene change score for
>> every frame
>> +to detect scene change.
>> +
>> + at 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:
>> +
>> + at table @option
>> + at 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
>> + at code{[0., 100.]}.
>> +
>> +Default value is @code{10.}.
>> +
>> + at item sc_pass, s
>> +Set the scene change pass the frame to the next filter or not. Default
>> value is @code{0}
>> +You can enable it if you want to get snapshot of scene change frames.
>> + at end table
>> +
>>  @anchor{selectivecolor}
>>  @section selectivecolor
>>
>> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
>> index b99ecc8c26..f6c6ba5d45 100644
>> --- a/libavfilter/Makefile
>> +++ b/libavfilter/Makefile
>> @@ -356,6 +356,7 @@ 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_SELECT_FILTER)                 += f_select.o
>>  OBJS-$(CONFIG_SELECTIVECOLOR_FILTER)         += vf_selectivecolor.o
>>  OBJS-$(CONFIG_SENDCMD_FILTER)                += f_sendcmd.o
>> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
>> index 788652ab1e..69a4d5e8e5 100644
>> --- a/libavfilter/allfilters.c
>> +++ b/libavfilter/allfilters.c
>> @@ -338,6 +338,7 @@ 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_select;
>>  extern AVFilter ff_vf_selectivecolor;
>>  extern AVFilter ff_vf_sendcmd;
>> diff --git a/libavfilter/vf_scenechangedetect.c
>> b/libavfilter/vf_scenechangedetect.c
>> new file mode 100644
>> index 0000000000..269fa399d0
>> --- /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 level",
>> OFFSET(threshold),  AV_OPT_TYPE_DOUBLE,   {.dbl = 10.},     0,  100., V|F
>> },
>> +    { "t",           "set scene change detect level",
>> OFFSET(threshold),  AV_OPT_TYPE_DOUBLE,   {.dbl = 10.},     0,  100., V|F
>> },
>> +    { "sc_pass",     "set scene change frame pass",     OFFSET(sc_pass),
>> AV_OPT_TYPE_BOOL,       {.dbl = 0  },     0,    1., V|F },
>> +    { "s",           "set scene change frame pass",     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          = "scenechangedetect",
>> +    .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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