/*
  * Copyright (c) 2012 Fredrik Mellbin
  * Copyright (c) 2013 Clément Bœsch
  *
  * 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
  */
 
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "libavutil/timestamp.h"
 #include "avfilter.h"
 #include "internal.h"
 
 #define INPUT_MAIN     0
 #define INPUT_CLEANSRC 1
 
 struct qitem {
     AVFrame *frame;
     int64_t maxbdiff;
     int64_t totdiff;
 };
 

 typedef struct DecimateContext {

     const AVClass *class;
     struct qitem *queue;    ///< window of cycle frames and the associated data diff
     int fid;                ///< current frame id in the queue
     int filled;             ///< 1 if the queue is filled, 0 otherwise
     AVFrame *last;          ///< last frame from the previous queue
     AVFrame **clean_src;    ///< frame queue for the clean source
     int got_frame[2];       ///< frame request flag for each input stream

     AVRational ts_unit;     ///< timestamp units for the output frames

     int64_t start_pts;      ///< base for output timestamps

     uint32_t eof;           ///< bitmask for end of stream
     int hsub, vsub;         ///< chroma subsampling values
     int depth;
     int nxblocks, nyblocks;
     int bdiffsize;
     int64_t *bdiffs;
 
     /* options */
     int cycle;
     double dupthresh_flt;
     double scthresh_flt;
     int64_t dupthresh;
     int64_t scthresh;
     int blockx, blocky;
     int ppsrc;
     int chroma;
 } DecimateContext;
 
 #define OFFSET(x) offsetof(DecimateContext, x)
 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption decimate_options[] = {
     { "cycle",     "set the number of frame from which one will be dropped", OFFSET(cycle), AV_OPT_TYPE_INT, {.i64 = 5}, 2, 25, FLAGS },
     { "dupthresh", "set duplicate threshold",    OFFSET(dupthresh_flt), AV_OPT_TYPE_DOUBLE, {.dbl =  1.1}, 0, 100, FLAGS },
     { "scthresh",  "set scene change threshold", OFFSET(scthresh_flt),  AV_OPT_TYPE_DOUBLE, {.dbl = 15.0}, 0, 100, FLAGS },
     { "blockx",    "set the size of the x-axis blocks used during metric calculations", OFFSET(blockx), AV_OPT_TYPE_INT, {.i64 = 32}, 4, 1<<9, FLAGS },
     { "blocky",    "set the size of the y-axis blocks used during metric calculations", OFFSET(blocky), AV_OPT_TYPE_INT, {.i64 = 32}, 4, 1<<9, FLAGS },

     { "ppsrc",     "mark main input as a pre-processed input and activate clean source input stream", OFFSET(ppsrc), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
     { "chroma",    "set whether or not chroma is considered in the metric calculations", OFFSET(chroma), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, FLAGS },

     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(decimate);
 
 static void calc_diffs(const DecimateContext *dm, struct qitem *q,
                        const AVFrame *f1, const AVFrame *f2)
 {
     int64_t maxdiff = -1;
     int64_t *bdiffs = dm->bdiffs;
     int plane, i, j;
 
     memset(bdiffs, 0, dm->bdiffsize * sizeof(*bdiffs));
 

     for (plane = 0; plane < (dm->chroma && f1->data[2] ? 3 : 1); plane++) {

         int x, y, xl;
         const int linesize1 = f1->linesize[plane];
         const int linesize2 = f2->linesize[plane];
         const uint8_t *f1p = f1->data[plane];
         const uint8_t *f2p = f2->data[plane];

         int width    = plane ? AV_CEIL_RSHIFT(f1->width,  dm->hsub) : f1->width;
         int height   = plane ? AV_CEIL_RSHIFT(f1->height, dm->vsub) : f1->height;

         int hblockx  = dm->blockx / 2;
         int hblocky  = dm->blocky / 2;
 
         if (plane) {
             hblockx >>= dm->hsub;
             hblocky >>= dm->vsub;
         }
 
         for (y = 0; y < height; y++) {
             int ydest = y / hblocky;
             int xdest = 0;
 
 #define CALC_DIFF(nbits) do {                               \
     for (x = 0; x < width; x += hblockx) {                  \
         int64_t acc = 0;                                    \
         int m = FFMIN(width, x + hblockx);                  \
         for (xl = x; xl < m; xl++)                          \
             acc += abs(((const uint##nbits##_t *)f1p)[xl] - \
                        ((const uint##nbits##_t *)f2p)[xl]); \
         bdiffs[ydest * dm->nxblocks + xdest] += acc;        \
         xdest++;                                            \
     }                                                       \
 } while (0)
             if (dm->depth == 8) CALC_DIFF(8);
             else                CALC_DIFF(16);
 
             f1p += linesize1;
             f2p += linesize2;
         }
     }
 
     for (i = 0; i < dm->nyblocks - 1; i++) {
         for (j = 0; j < dm->nxblocks - 1; j++) {
             int64_t tmp = bdiffs[      i * dm->nxblocks + j    ]
                         + bdiffs[      i * dm->nxblocks + j + 1]
                         + bdiffs[(i + 1) * dm->nxblocks + j    ]
                         + bdiffs[(i + 1) * dm->nxblocks + j + 1];
             if (tmp > maxdiff)
                 maxdiff = tmp;
         }
     }
 
     q->totdiff = 0;
     for (i = 0; i < dm->bdiffsize; i++)
         q->totdiff += bdiffs[i];
     q->maxbdiff = maxdiff;
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     int scpos = -1, duppos = -1;
     int drop = INT_MIN, i, lowest = 0, ret;
     AVFilterContext *ctx  = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     DecimateContext *dm   = ctx->priv;
     AVFrame *prv;
 
     /* update frames queue(s) */
     if (FF_INLINK_IDX(inlink) == INPUT_MAIN) {
         dm->queue[dm->fid].frame = in;
         dm->got_frame[INPUT_MAIN] = 1;
     } else {
         dm->clean_src[dm->fid] = in;
         dm->got_frame[INPUT_CLEANSRC] = 1;
     }
     if (!dm->got_frame[INPUT_MAIN] || (dm->ppsrc && !dm->got_frame[INPUT_CLEANSRC]))
         return 0;
     dm->got_frame[INPUT_MAIN] = dm->got_frame[INPUT_CLEANSRC] = 0;
 

     if (dm->ppsrc)
         in = dm->clean_src[dm->fid];
 

     if (in) {
         /* update frame metrics */

         prv = dm->fid ? (dm->ppsrc ? dm->clean_src[dm->fid - 1] : dm->queue[dm->fid - 1].frame) : dm->last;

         if (!prv) {
             dm->queue[dm->fid].maxbdiff = INT64_MAX;
             dm->queue[dm->fid].totdiff  = INT64_MAX;
         } else {
             calc_diffs(dm, &dm->queue[dm->fid], prv, in);
         }

         if (++dm->fid != dm->cycle)
             return 0;
         av_frame_free(&dm->last);
         dm->last = av_frame_clone(in);
         dm->fid = 0;
 
         /* we have a complete cycle, select the frame to drop */
         lowest = 0;
         for (i = 0; i < dm->cycle; i++) {
             if (dm->queue[i].totdiff > dm->scthresh)
                 scpos = i;
             if (dm->queue[i].maxbdiff < dm->queue[lowest].maxbdiff)
                 lowest = i;
         }
         if (dm->queue[lowest].maxbdiff < dm->dupthresh)
             duppos = lowest;
         drop = scpos >= 0 && duppos < 0 ? scpos : lowest;
     }
 
     /* metrics debug */
     if (av_log_get_level() >= AV_LOG_DEBUG) {
         av_log(ctx, AV_LOG_DEBUG, "1/%d frame drop:\n", dm->cycle);
         for (i = 0; i < dm->cycle && dm->queue[i].frame; i++) {
             av_log(ctx, AV_LOG_DEBUG,"  #%d: totdiff=%08"PRIx64" maxbdiff=%08"PRIx64"%s%s%s%s\n",
                    i + 1, dm->queue[i].totdiff, dm->queue[i].maxbdiff,
                    i == scpos  ? " sc"     : "",
                    i == duppos ? " dup"    : "",
                    i == lowest ? " lowest" : "",
                    i == drop   ? " [DROP]" : "");
         }
     }
 
     /* push all frames except the drop */
     ret = 0;
     for (i = 0; i < dm->cycle && dm->queue[i].frame; i++) {
         if (i == drop) {
             if (dm->ppsrc)
                 av_frame_free(&dm->clean_src[i]);
             av_frame_free(&dm->queue[i].frame);
         } else {
             AVFrame *frame = dm->queue[i].frame;

             if (frame->pts != AV_NOPTS_VALUE && dm->start_pts == AV_NOPTS_VALUE)
                 dm->start_pts = frame->pts;

             if (dm->ppsrc) {
                 av_frame_free(&frame);
                 frame = dm->clean_src[i];
             }

             frame->pts = av_rescale_q(outlink->frame_count_in, dm->ts_unit, (AVRational){1,1}) +

                          (dm->start_pts == AV_NOPTS_VALUE ? 0 : dm->start_pts);

             ret = ff_filter_frame(outlink, frame);
             if (ret < 0)
                 break;
         }
     }
 
     return ret;
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     int max_value;
     AVFilterContext *ctx = inlink->dst;
     DecimateContext *dm = ctx->priv;
     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
     const int w = inlink->w;
     const int h = inlink->h;
 
     dm->hsub      = pix_desc->log2_chroma_w;
     dm->vsub      = pix_desc->log2_chroma_h;

     dm->depth     = pix_desc->comp[0].depth;

     max_value     = (1 << dm->depth) - 1;
     dm->scthresh  = (int64_t)(((int64_t)max_value *          w * h          * dm->scthresh_flt)  / 100);
     dm->dupthresh = (int64_t)(((int64_t)max_value * dm->blockx * dm->blocky * dm->dupthresh_flt) / 100);
     dm->nxblocks  = (w + dm->blockx/2 - 1) / (dm->blockx/2);
     dm->nyblocks  = (h + dm->blocky/2 - 1) / (dm->blocky/2);
     dm->bdiffsize = dm->nxblocks * dm->nyblocks;

     dm->bdiffs    = av_malloc_array(dm->bdiffsize, sizeof(*dm->bdiffs));

     dm->queue     = av_calloc(dm->cycle, sizeof(*dm->queue));
 
     if (!dm->bdiffs || !dm->queue)
         return AVERROR(ENOMEM);
 
     if (dm->ppsrc) {
         dm->clean_src = av_calloc(dm->cycle, sizeof(*dm->clean_src));
         if (!dm->clean_src)
             return AVERROR(ENOMEM);
     }
 
     return 0;
 }
 
 static av_cold int decimate_init(AVFilterContext *ctx)
 {

     DecimateContext *dm = ctx->priv;

     AVFilterPad pad = {
         .name         = av_strdup("main"),
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
         .config_props = config_input,
     };

     int ret;

 
     if (!pad.name)
         return AVERROR(ENOMEM);

     if ((ret = ff_insert_inpad(ctx, INPUT_MAIN, &pad)) < 0) {
         av_freep(&pad.name);
         return ret;
     }

 
     if (dm->ppsrc) {
         pad.name = av_strdup("clean_src");
         pad.config_props = NULL;
         if (!pad.name)
             return AVERROR(ENOMEM);

         if ((ret = ff_insert_inpad(ctx, INPUT_CLEANSRC, &pad)) < 0) {
             av_freep(&pad.name);
             return ret;
         }

     }
 
     if ((dm->blockx & (dm->blockx - 1)) ||
         (dm->blocky & (dm->blocky - 1))) {
         av_log(ctx, AV_LOG_ERROR, "blockx and blocky settings must be power of two\n");
         return AVERROR(EINVAL);
     }
 

     dm->start_pts = AV_NOPTS_VALUE;
 

     return 0;
 }
 
 static av_cold void decimate_uninit(AVFilterContext *ctx)
 {
     int i;
     DecimateContext *dm = ctx->priv;
 
     av_frame_free(&dm->last);
     av_freep(&dm->bdiffs);
     av_freep(&dm->queue);
     av_freep(&dm->clean_src);
     for (i = 0; i < ctx->nb_inputs; i++)
         av_freep(&ctx->input_pads[i].name);
 }
 
 static int request_inlink(AVFilterContext *ctx, int lid)
 {
     int ret = 0;
     DecimateContext *dm = ctx->priv;
 
     if (!dm->got_frame[lid]) {
         AVFilterLink *inlink = ctx->inputs[lid];
         ret = ff_request_frame(inlink);
         if (ret == AVERROR_EOF) { // flushing
             dm->eof |= 1 << lid;
             ret = filter_frame(inlink, NULL);
         }
     }
     return ret;
 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     int ret;
     AVFilterContext *ctx = outlink->src;
     DecimateContext *dm = ctx->priv;
     const uint32_t eof_mask = 1<<INPUT_MAIN | dm->ppsrc<<INPUT_CLEANSRC;
 
     if ((dm->eof & eof_mask) == eof_mask) // flush done?
         return AVERROR_EOF;
     if ((ret = request_inlink(ctx, INPUT_MAIN)) < 0)
         return ret;
     if (dm->ppsrc && (ret = request_inlink(ctx, INPUT_CLEANSRC)) < 0)
         return ret;
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum AVPixelFormat pix_fmts[] = {
 #define PF_NOALPHA(suf) AV_PIX_FMT_YUV420##suf,  AV_PIX_FMT_YUV422##suf,  AV_PIX_FMT_YUV444##suf
 #define PF_ALPHA(suf)   AV_PIX_FMT_YUVA420##suf, AV_PIX_FMT_YUVA422##suf, AV_PIX_FMT_YUVA444##suf
 #define PF(suf)         PF_NOALPHA(suf), PF_ALPHA(suf)
         PF(P), PF(P9), PF(P10), PF_NOALPHA(P12), PF_NOALPHA(P14), PF(P16),

         AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
         AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY16,

         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_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     DecimateContext *dm = ctx->priv;
     const AVFilterLink *inlink =
         ctx->inputs[dm->ppsrc ? INPUT_CLEANSRC : INPUT_MAIN];
     AVRational fps = inlink->frame_rate;
 
     if (!fps.num || !fps.den) {
         av_log(ctx, AV_LOG_ERROR, "The input needs a constant frame rate; "
                "current rate of %d/%d is invalid\n", fps.num, fps.den);
         return AVERROR(EINVAL);
     }
     fps = av_mul_q(fps, (AVRational){dm->cycle - 1, dm->cycle});
     av_log(ctx, AV_LOG_VERBOSE, "FPS: %d/%d -> %d/%d\n",
            inlink->frame_rate.num, inlink->frame_rate.den, fps.num, fps.den);
     outlink->time_base  = inlink->time_base;
     outlink->frame_rate = fps;
     outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;
     outlink->w = inlink->w;
     outlink->h = inlink->h;

     dm->ts_unit = av_inv_q(av_mul_q(fps, outlink->time_base));

     return 0;
 }
 
 static const AVFilterPad decimate_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .request_frame = request_frame,
         .config_props  = config_output,
     },
     { NULL }
 };
 

 AVFilter ff_vf_decimate = {

     .name          = "decimate",
     .description   = NULL_IF_CONFIG_SMALL("Decimate frames (post field matching filter)."),
     .init          = decimate_init,
     .uninit        = decimate_uninit,
     .priv_size     = sizeof(DecimateContext),
     .query_formats = query_formats,
     .outputs       = decimate_outputs,
     .priv_class    = &decimate_class,
     .flags         = AVFILTER_FLAG_DYNAMIC_INPUTS,
 };