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/*

 * Copyright (c) 2002 A'rpi

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 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 General Public License for more details.

 *

 * You should have received a copy of the GNU 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

 * border detection filter

 * Ported from MPlayer libmpcodecs/vf_cropdetect.c.

 */

#include "libavutil/imgutils.h"

#include "libavutil/internal.h"

#include "libavutil/opt.h"

#include "avfilter.h"

#include "formats.h"

#include "internal.h"

#include "video.h"

typedef struct {

    const AVClass *class;

    int x1, y1, x2, y2;

    int limit;

    int round;

    int reset_count;

    int frame_nb;

    int max_pixsteps[4];

} CropDetectContext;

static int query_formats(AVFilterContext *ctx)

{

    static const enum AVPixelFormat pix_fmts[] = {

        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUVJ420P,

        AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUVJ422P,

        AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUVJ444P,

        AV_PIX_FMT_YUV411P, AV_PIX_FMT_GRAY8,

        AV_PIX_FMT_NV12,    AV_PIX_FMT_NV21,

        AV_PIX_FMT_NONE

    };

    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));

    return 0;

}

static int checkline(void *ctx, const unsigned char *src, int stride, int len, int bpp)

{

    int total = 0;

    int div = len;

    switch (bpp) {

    case 1:

        while (--len >= 0) {

            total += src[0];

            src += stride;

        }

        break;

    case 3:

    case 4:

        while (--len >= 0) {

            total += src[0] + src[1] + src[2];

            src += stride;

        }

        div *= 3;

        break;

    }

    total /= div;

    av_log(ctx, AV_LOG_DEBUG, "total:%d\n", total);

    return total;

}

static av_cold int init(AVFilterContext *ctx)

{

    CropDetectContext *s = ctx->priv;

    s->frame_nb = -2;

    av_log(ctx, AV_LOG_VERBOSE, "limit:%d round:%d reset_count:%d\n",

           s->limit, s->round, s->reset_count);

    return 0;

}

static int config_input(AVFilterLink *inlink)

{

    AVFilterContext *ctx = inlink->dst;

    CropDetectContext *s = ctx->priv;

    av_image_fill_max_pixsteps(s->max_pixsteps, NULL,

                               av_pix_fmt_desc_get(inlink->format));

    s->x1 = inlink->w - 1;

    s->y1 = inlink->h - 1;

    s->x2 = 0;

    s->y2 = 0;

    return 0;

}

#define SET_META(key, value) \

    snprintf(buf, sizeof(buf), "%d", value);  \

    av_dict_set(metadata, key, buf, 0)

static int filter_frame(AVFilterLink *inlink, AVFrame *frame)

{

    AVFilterContext *ctx = inlink->dst;

    CropDetectContext *s = ctx->priv;

    int bpp = s->max_pixsteps[0];

    int w, h, x, y, shrink_by;

    AVDictionary **metadata;

    char buf[32];

    // ignore first 2 frames - they may be empty

    if (++s->frame_nb > 0) {

        metadata = avpriv_frame_get_metadatap(frame);

        // Reset the crop area every reset_count frames, if reset_count is > 0

        if (s->reset_count > 0 && s->frame_nb > s->reset_count) {

            s->x1 = frame->width  - 1;

            s->y1 = frame->height - 1;

            s->x2 = 0;

            s->y2 = 0;

            s->frame_nb = 1;

        }

        for (y = 0; y < s->y1; y++) {

            if (checkline(ctx, frame->data[0] + frame->linesize[0] * y, bpp, frame->width, bpp) > s->limit) {

                s->y1 = y;

                break;

            }

        }

        for (y = frame->height - 1; y > s->y2; y--) {

            if (checkline(ctx, frame->data[0] + frame->linesize[0] * y, bpp, frame->width, bpp) > s->limit) {

                s->y2 = y;

                break;

            }

        }

        for (y = 0; y < s->x1; y++) {

            if (checkline(ctx, frame->data[0] + bpp*y, frame->linesize[0], frame->height, bpp) > s->limit) {

                s->x1 = y;

                break;

            }

        }

        for (y = frame->width - 1; y > s->x2; y--) {

            if (checkline(ctx, frame->data[0] + bpp*y, frame->linesize[0], frame->height, bpp) > s->limit) {

                s->x2 = y;

                break;

            }

        }

        // round x and y (up), important for yuv colorspaces

        // make sure they stay rounded!

        x = (s->x1+1) & ~1;

        y = (s->y1+1) & ~1;

        w = s->x2 - x + 1;

        h = s->y2 - y + 1;

        // w and h must be divisible by 2 as well because of yuv

        // colorspace problems.

        if (s->round <= 1)

            s->round = 16;

        if (s->round % 2)

            s->round *= 2;

        shrink_by = w % s->round;

        w -= shrink_by;

        x += (shrink_by/2 + 1) & ~1;

        shrink_by = h % s->round;

        h -= shrink_by;

        y += (shrink_by/2 + 1) & ~1;

        SET_META("lavfi.cropdetect.x1", s->x1);

        SET_META("lavfi.cropdetect.x2", s->x2);

        SET_META("lavfi.cropdetect.y1", s->y1);

        SET_META("lavfi.cropdetect.y2", s->y2);

        SET_META("lavfi.cropdetect.w",  w);

        SET_META("lavfi.cropdetect.h",  h);

        SET_META("lavfi.cropdetect.x",  x);

        SET_META("lavfi.cropdetect.y",  y);

        av_log(ctx, AV_LOG_INFO,

               "x1:%d x2:%d y1:%d y2:%d w:%d h:%d x:%d y:%d pts:%"PRId64" t:%f crop=%d:%d:%d:%d\n",

               s->x1, s->x2, s->y1, s->y2, w, h, x, y, frame->pts,

               frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),

               w, h, x, y);

    }

    return ff_filter_frame(inlink->dst->outputs[0], frame);

}

#define OFFSET(x) offsetof(CropDetectContext, x)

#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

static const AVOption cropdetect_options[] = {

    { "limit", "Threshold below which the pixel is considered black", OFFSET(limit),       AV_OPT_TYPE_INT, { .i64 = 24 }, 0, 255, FLAGS },

    { "round", "Value by which the width/height should be divisible", OFFSET(round),       AV_OPT_TYPE_INT, { .i64 = 16 }, 0, INT_MAX, FLAGS },

    { "reset", "Recalculate the crop area after this many frames",    OFFSET(reset_count), AV_OPT_TYPE_INT, { .i64 = 0 },  0, INT_MAX, FLAGS },

    { "reset_count", "Recalculate the crop area after this many frames",OFFSET(reset_count),AV_OPT_TYPE_INT,{ .i64 = 0 },  0, INT_MAX, FLAGS },

    { NULL }

};

AVFILTER_DEFINE_CLASS(cropdetect);

static const AVFilterPad avfilter_vf_cropdetect_inputs[] = {

    {

        .name         = "default",

        .type         = AVMEDIA_TYPE_VIDEO,

        .config_props = config_input,

        .filter_frame = filter_frame,

    },

    { NULL }

};

static const AVFilterPad avfilter_vf_cropdetect_outputs[] = {

    {

        .name = "default",

        .type = AVMEDIA_TYPE_VIDEO

    },

    { NULL }

};

AVFilter avfilter_vf_cropdetect = {

    .name          = "cropdetect",

    .description   = NULL_IF_CONFIG_SMALL("Auto-detect crop size."),

    .priv_size     = sizeof(CropDetectContext),

    .priv_class    = &cropdetect_class,

    .init          = init,

    .query_formats = query_formats,

    .inputs        = avfilter_vf_cropdetect_inputs,

    .outputs       = avfilter_vf_cropdetect_outputs,

    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,

};