/*
  * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
  *

  * 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
  * Motion Compensation Deinterlacer
  * Ported from MPlayer libmpcodecs/vf_mcdeint.c.
  *
  * Known Issues:
  *
  * The motion estimation is somewhat at the mercy of the input, if the
  * input frames are created purely based on spatial interpolation then
  * for example a thin black line or another random and not
  * interpolateable pattern will cause problems.
  * Note: completely ignoring the "unavailable" lines during motion
  * estimation did not look any better, so the most obvious solution
  * would be to improve tfields or penalize problematic motion vectors.
  *
  * If non iterative ME is used then snow currently ignores the OBMC
  * window and as a result sometimes creates artifacts.
  *
  * Only past frames are used, we should ideally use future frames too,
  * something like filtering the whole movie in forward and then

  * backward direction seems like an interesting idea but the current

  * filter framework is FAR from supporting such things.
  *
  * Combining the motion compensated image with the input image also is
  * not as trivial as it seems, simple blindly taking even lines from
  * one and odd ones from the other does not work at all as ME/MC
  * sometimes has nothing in the previous frames which matches the
  * current. The current algorithm has been found by trial and error
  * and almost certainly can be improved...
  */
 
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "libavcodec/avcodec.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 
 enum MCDeintMode {
     MODE_FAST = 0,
     MODE_MEDIUM,
     MODE_SLOW,
     MODE_EXTRA_SLOW,
     MODE_NB,
 };
 
 enum MCDeintParity {
     PARITY_TFF  =  0, ///< top field first
     PARITY_BFF  =  1, ///< bottom field first
 };
 

 typedef struct MCDeintContext {

     const AVClass *class;

     int mode;           ///< MCDeintMode
     int parity;         ///< MCDeintParity

     int qp;
     AVCodecContext *enc_ctx;
 } MCDeintContext;
 
 #define OFFSET(x) offsetof(MCDeintContext, x)
 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 #define CONST(name, help, val, unit) { name, help, 0, AV_OPT_TYPE_CONST, {.i64=val}, INT_MIN, INT_MAX, FLAGS, unit }
 
 static const AVOption mcdeint_options[] = {
     { "mode", "set mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_FAST}, 0, MODE_NB-1, FLAGS, .unit="mode" },
     CONST("fast",       NULL, MODE_FAST,       "mode"),
     CONST("medium",     NULL, MODE_MEDIUM,     "mode"),
     CONST("slow",       NULL, MODE_SLOW,       "mode"),
     CONST("extra_slow", NULL, MODE_EXTRA_SLOW, "mode"),
 
     { "parity", "set the assumed picture field parity", OFFSET(parity), AV_OPT_TYPE_INT, {.i64=PARITY_BFF}, -1, 1, FLAGS, "parity" },
     CONST("tff", "assume top field first",    PARITY_TFF, "parity"),
     CONST("bff", "assume bottom field first", PARITY_BFF, "parity"),
 
     { "qp", "set qp", OFFSET(qp), AV_OPT_TYPE_INT, {.i64=1}, INT_MIN, INT_MAX, FLAGS },
     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(mcdeint);
 
 static int config_props(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     MCDeintContext *mcdeint = ctx->priv;
     AVCodec *enc;
     AVCodecContext *enc_ctx;
     AVDictionary *opts = NULL;
     int ret;
 
     if (!(enc = avcodec_find_encoder(AV_CODEC_ID_SNOW))) {
         av_log(ctx, AV_LOG_ERROR, "Snow encoder is not enabled in libavcodec\n");
         return AVERROR(EINVAL);
     }
 
     mcdeint->enc_ctx = avcodec_alloc_context3(enc);
     if (!mcdeint->enc_ctx)
         return AVERROR(ENOMEM);
     enc_ctx = mcdeint->enc_ctx;
     enc_ctx->width  = inlink->w;
     enc_ctx->height = inlink->h;
     enc_ctx->time_base = (AVRational){1,25};  // meaningless

     enc_ctx->gop_size = INT_MAX;

     enc_ctx->max_b_frames = 0;
     enc_ctx->pix_fmt = AV_PIX_FMT_YUV420P;

     enc_ctx->flags = AV_CODEC_FLAG_QSCALE | AV_CODEC_FLAG_LOW_DELAY;

     enc_ctx->strict_std_compliance = FF_COMPLIANCE_EXPERIMENTAL;
     enc_ctx->global_quality = 1;
     enc_ctx->me_cmp = enc_ctx->me_sub_cmp = FF_CMP_SAD;
     enc_ctx->mb_cmp = FF_CMP_SSE;
     av_dict_set(&opts, "memc_only", "1", 0);

     av_dict_set(&opts, "no_bitstream", "1", 0);

 
     switch (mcdeint->mode) {
     case MODE_EXTRA_SLOW:
         enc_ctx->refs = 3;
     case MODE_SLOW:

         av_dict_set(&opts, "motion_est", "iter", 0);

     case MODE_MEDIUM:

         enc_ctx->flags |= AV_CODEC_FLAG_4MV;

         enc_ctx->dia_size = 2;
     case MODE_FAST:

         enc_ctx->flags |= AV_CODEC_FLAG_QPEL;

     }
 
     ret = avcodec_open2(enc_ctx, enc, &opts);
     av_dict_free(&opts);
     if (ret < 0)
         return ret;
 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     MCDeintContext *mcdeint = ctx->priv;
 

     avcodec_free_context(&mcdeint->enc_ctx);

 }
 
 static int query_formats(AVFilterContext *ctx)
 {

     static const enum AVPixelFormat pix_fmts[] = {

         AV_PIX_FMT_YUV420P, 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 filter_frame(AVFilterLink *inlink, AVFrame *inpic)
 {
     MCDeintContext *mcdeint = inlink->dst->priv;
     AVFilterLink *outlink = inlink->dst->outputs[0];
     AVFrame *outpic, *frame_dec;

     AVPacket pkt = {0};

     int x, y, i, ret, got_frame = 0;
 
     outpic = ff_get_video_buffer(outlink, outlink->w, outlink->h);
     if (!outpic) {
         av_frame_free(&inpic);
         return AVERROR(ENOMEM);
     }
     av_frame_copy_props(outpic, inpic);
     inpic->quality = mcdeint->qp * FF_QP2LAMBDA;
 
     av_init_packet(&pkt);
 
     ret = avcodec_encode_video2(mcdeint->enc_ctx, &pkt, inpic, &got_frame);
     if (ret < 0)
         goto end;
 
     frame_dec = mcdeint->enc_ctx->coded_frame;
 
     for (i = 0; i < 3; i++) {
         int is_chroma = !!i;

         int w = AV_CEIL_RSHIFT(inlink->w, is_chroma);
         int h = AV_CEIL_RSHIFT(inlink->h, is_chroma);

         int fils = frame_dec->linesize[i];
         int srcs = inpic    ->linesize[i];
         int dsts = outpic   ->linesize[i];
 
         for (y = 0; y < h; y++) {
             if ((y ^ mcdeint->parity) & 1) {
                 for (x = 0; x < w; x++) {
                     uint8_t *filp = &frame_dec->data[i][x + y*fils];
                     uint8_t *srcp = &inpic    ->data[i][x + y*srcs];
                     uint8_t *dstp = &outpic   ->data[i][x + y*dsts];
 
                     if (y > 0 && y < h-1){
                         int is_edge = x < 3 || x > w-4;
                         int diff0 = filp[-fils] - srcp[-srcs];
                         int diff1 = filp[+fils] - srcp[+srcs];
                         int temp = filp[0];
 
 #define DELTA(j) av_clip(j, -x, w-1-x)
 
 #define GET_SCORE_EDGE(j)\
    FFABS(srcp[-srcs+DELTA(-1+(j))] - srcp[+srcs+DELTA(-1-(j))])+\
    FFABS(srcp[-srcs+DELTA(j)     ] - srcp[+srcs+DELTA(  -(j))])+\
    FFABS(srcp[-srcs+DELTA(1+(j)) ] - srcp[+srcs+DELTA( 1-(j))])
 
 #define GET_SCORE(j)\
    FFABS(srcp[-srcs-1+(j)] - srcp[+srcs-1-(j)])+\
    FFABS(srcp[-srcs  +(j)] - srcp[+srcs  -(j)])+\
    FFABS(srcp[-srcs+1+(j)] - srcp[+srcs+1-(j)])
 
 #define CHECK_EDGE(j)\
     {   int score = GET_SCORE_EDGE(j);\
         if (score < spatial_score){\
             spatial_score = score;\
             diff0 = filp[-fils+DELTA(j)]    - srcp[-srcs+DELTA(j)];\
             diff1 = filp[+fils+DELTA(-(j))] - srcp[+srcs+DELTA(-(j))];\
 
 #define CHECK(j)\
     {   int score = GET_SCORE(j);\
         if (score < spatial_score){\
             spatial_score= score;\
             diff0 = filp[-fils+(j)] - srcp[-srcs+(j)];\
             diff1 = filp[+fils-(j)] - srcp[+srcs-(j)];\
 
                         if (is_edge) {
                             int spatial_score = GET_SCORE_EDGE(0) - 1;
                             CHECK_EDGE(-1) CHECK_EDGE(-2) }} }}
                             CHECK_EDGE( 1) CHECK_EDGE( 2) }} }}
                         } else {
                             int spatial_score = GET_SCORE(0) - 1;
                             CHECK(-1) CHECK(-2) }} }}
                             CHECK( 1) CHECK( 2) }} }}
                         }
 
 
                         if (diff0 + diff1 > 0)
                             temp -= (diff0 + diff1 - FFABS(FFABS(diff0) - FFABS(diff1)) / 2) / 2;
                         else
                             temp -= (diff0 + diff1 + FFABS(FFABS(diff0) - FFABS(diff1)) / 2) / 2;
                         *filp = *dstp = temp > 255U ? ~(temp>>31) : temp;
                     } else {
                         *dstp = *filp;
                     }
                 }
             }
         }
 
         for (y = 0; y < h; y++) {
             if (!((y ^ mcdeint->parity) & 1)) {
                 for (x = 0; x < w; x++) {
                     frame_dec->data[i][x + y*fils] =
                     outpic   ->data[i][x + y*dsts] = inpic->data[i][x + y*srcs];
                 }
             }
         }
     }
     mcdeint->parity ^= 1;
 
 end:

     av_packet_unref(&pkt);

     av_frame_free(&inpic);

     if (ret < 0) {
         av_frame_free(&outpic);

         return ret;

     }

     return ff_filter_frame(outlink, outpic);
 }
 
 static const AVFilterPad mcdeint_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
         .config_props = config_props,
     },
     { NULL }
 };
 
 static const AVFilterPad mcdeint_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 

 AVFilter ff_vf_mcdeint = {

     .name          = "mcdeint",
     .description   = NULL_IF_CONFIG_SMALL("Apply motion compensating deinterlacing."),
     .priv_size     = sizeof(MCDeintContext),
     .uninit        = uninit,
     .query_formats = query_formats,
     .inputs        = mcdeint_inputs,
     .outputs       = mcdeint_outputs,
     .priv_class    = &mcdeint_class,
 };