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/*

 * Copyright (c) 2003 Rich Felker

 * Copyright (c) 2012 Stefano Sabatini

 *

 * 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 mpdecimate filter, ported from libmpcodecs/vf_decimate.c by

 * Rich Felker.

 */

#include "libavutil/opt.h"

#include "libavutil/pixdesc.h"

#include "libavutil/pixelutils.h"

#include "libavutil/timestamp.h"

#include "avfilter.h"

#include "internal.h"

#include "formats.h"

#include "video.h"

typedef struct {

    const AVClass *class;

    int lo, hi;                    ///< lower and higher threshold number of differences

                                   ///< values for 8x8 blocks

    float frac;                    ///< threshold of changed pixels over the total fraction

    int max_drop_count;            ///< if positive: maximum number of sequential frames to drop

                                   ///< if negative: minimum number of frames between two drops

    int drop_count;                ///< if positive: number of frames sequentially dropped

                                   ///< if negative: number of sequential frames which were not dropped

    int hsub, vsub;                ///< chroma subsampling values

    AVFrame *ref;                  ///< reference picture

    av_pixelutils_sad_fn sad;      ///< sum of absolute difference function

} DecimateContext;

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

#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

static const AVOption mpdecimate_options[] = {

    { "max",  "set the maximum number of consecutive dropped frames (positive), or the minimum interval between dropped frames (negative)",

      OFFSET(max_drop_count), AV_OPT_TYPE_INT, {.i64=0}, INT_MIN, INT_MAX, FLAGS },

    { "hi",   "set high dropping threshold", OFFSET(hi), AV_OPT_TYPE_INT, {.i64=64*12}, INT_MIN, INT_MAX, FLAGS },

    { "lo",   "set low dropping threshold", OFFSET(lo), AV_OPT_TYPE_INT, {.i64=64*5}, INT_MIN, INT_MAX, FLAGS },

    { "frac", "set fraction dropping threshold",  OFFSET(frac), AV_OPT_TYPE_FLOAT, {.dbl=0.33}, 0, 1, FLAGS },

    { NULL }

};

AVFILTER_DEFINE_CLASS(mpdecimate);

/**

 * Return 1 if the two planes are different, 0 otherwise.

 */

static int diff_planes(AVFilterContext *ctx,

                       uint8_t *cur, int cur_linesize,

                       uint8_t *ref, int ref_linesize,

                       int w, int h)

{

    DecimateContext *decimate = ctx->priv;

    int x, y;

    int d, c = 0;

    int t = (w/16)*(h/16)*decimate->frac;

    /* compute difference for blocks of 8x8 bytes */

    for (y = 0; y < h-7; y += 4) {

        for (x = 8; x < w-7; x += 4) {

            d = decimate->sad(cur + y*cur_linesize + x, cur_linesize,

                              ref + y*ref_linesize + x, ref_linesize);

            if (d > decimate->hi) {

                av_log(ctx, AV_LOG_DEBUG, "%d>=hi ", d);

                return 1;

            }

            if (d > decimate->lo) {

                c++;

                if (c > t) {

                    av_log(ctx, AV_LOG_DEBUG, "lo:%d>=%d ", c, t);

                    return 1;

                }

            }

        }

    }

    av_log(ctx, AV_LOG_DEBUG, "lo:%d<%d ", c, t);

    return 0;

}

/**

 * Tell if the frame should be decimated, for example if it is no much

 * different with respect to the reference frame ref.

 */

static int decimate_frame(AVFilterContext *ctx,

                          AVFrame *cur, AVFrame *ref)

{

    DecimateContext *decimate = ctx->priv;

    int plane;

    if (decimate->max_drop_count > 0 &&

        decimate->drop_count >= decimate->max_drop_count)

        return 0;

    if (decimate->max_drop_count < 0 &&

        (decimate->drop_count-1) > decimate->max_drop_count)

        return 0;

    for (plane = 0; ref->data[plane] && ref->linesize[plane]; plane++) {

        /* use 8x8 SAD even on subsampled planes.  The blocks won't match up with

         * luma blocks, but hopefully nobody is depending on this to catch

         * localized chroma changes that wouldn't exceed the thresholds when

         * diluted by using what's effectively a larger block size.

         */

        int vsub = plane == 1 || plane == 2 ? decimate->vsub : 0;

        int hsub = plane == 1 || plane == 2 ? decimate->hsub : 0;

        if (diff_planes(ctx,

                        cur->data[plane], cur->linesize[plane],

                        ref->data[plane], ref->linesize[plane],

                        FF_CEIL_RSHIFT(ref->width,  hsub),

                        FF_CEIL_RSHIFT(ref->height, vsub))) {

            emms_c();

            return 0;

        }

    }

    emms_c();

    return 1;

}

static av_cold int init(AVFilterContext *ctx)

{

    DecimateContext *decimate = ctx->priv;

    decimate->sad = av_pixelutils_get_sad_fn(3, 3, 0, ctx); // 8x8, not aligned on blocksize

    if (!decimate->sad)

        return AVERROR(EINVAL);

    av_log(ctx, AV_LOG_VERBOSE, "max_drop_count:%d hi:%d lo:%d frac:%f\n",

           decimate->max_drop_count, decimate->hi, decimate->lo, decimate->frac);

    return 0;

}

static av_cold void uninit(AVFilterContext *ctx)

{

    DecimateContext *decimate = ctx->priv;

    av_frame_free(&decimate->ref);

}

static int query_formats(AVFilterContext *ctx)

{

    static const enum AVPixelFormat pix_fmts[] = {

        AV_PIX_FMT_YUV444P,      AV_PIX_FMT_YUV422P,

        AV_PIX_FMT_YUV420P,      AV_PIX_FMT_YUV411P,

        AV_PIX_FMT_YUV410P,      AV_PIX_FMT_YUV440P,

        AV_PIX_FMT_YUVJ444P,     AV_PIX_FMT_YUVJ422P,

        AV_PIX_FMT_YUVJ420P,     AV_PIX_FMT_YUVJ440P,

        AV_PIX_FMT_YUVA420P,

        AV_PIX_FMT_GBRP,

        AV_PIX_FMT_YUVA444P,

        AV_PIX_FMT_YUVA422P,

        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;

    DecimateContext *decimate = ctx->priv;

    const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);

    decimate->hsub = pix_desc->log2_chroma_w;

    decimate->vsub = pix_desc->log2_chroma_h;

    return 0;

}

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

{

    DecimateContext *decimate = inlink->dst->priv;

    AVFilterLink *outlink = inlink->dst->outputs[0];

    int ret;

    if (decimate->ref && decimate_frame(inlink->dst, cur, decimate->ref)) {

        decimate->drop_count = FFMAX(1, decimate->drop_count+1);

    } else {

        av_frame_free(&decimate->ref);

        decimate->ref = cur;

        decimate->drop_count = FFMIN(-1, decimate->drop_count-1);

        if ((ret = ff_filter_frame(outlink, av_frame_clone(cur))) < 0)

            return ret;

    }

    av_log(inlink->dst, AV_LOG_DEBUG,

           "%s pts:%s pts_time:%s drop_count:%d\n",

           decimate->drop_count > 0 ? "drop" : "keep",

           av_ts2str(cur->pts), av_ts2timestr(cur->pts, &inlink->time_base),

           decimate->drop_count);

    if (decimate->drop_count > 0)

        av_frame_free(&cur);

    return 0;

}

static int request_frame(AVFilterLink *outlink)

{

    DecimateContext *decimate = outlink->src->priv;

    AVFilterLink *inlink = outlink->src->inputs[0];

    int ret;

    do {

        ret = ff_request_frame(inlink);

    } while (decimate->drop_count > 0 && ret >= 0);

    return ret;

}

static const AVFilterPad mpdecimate_inputs[] = {

    {

        .name         = "default",

        .type         = AVMEDIA_TYPE_VIDEO,

        .config_props = config_input,

        .filter_frame = filter_frame,

    },

    { NULL }

};

static const AVFilterPad mpdecimate_outputs[] = {

    {

        .name          = "default",

        .type          = AVMEDIA_TYPE_VIDEO,

        .request_frame = request_frame,

    },

    { NULL }

};

AVFilter ff_vf_mpdecimate = {

    .name          = "mpdecimate",

    .description   = NULL_IF_CONFIG_SMALL("Remove near-duplicate frames."),

    .init          = init,

    .uninit        = uninit,

    .priv_size     = sizeof(DecimateContext),

    .priv_class    = &mpdecimate_class,

    .query_formats = query_formats,

    .inputs        = mpdecimate_inputs,

    .outputs       = mpdecimate_outputs,

};