/*
  * 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
  */
 
 /**
  * A simple, relatively efficient and extremely slow DCT image denoiser.
  * @see http://www.ipol.im/pub/art/2011/ys-dct/
  */
 
 #include "libavcodec/avfft.h"
 #include "libavutil/eval.h"
 #include "libavutil/opt.h"
 #include "drawutils.h"
 #include "internal.h"
 
 #define NBITS 4
 #define BSIZE (1<<(NBITS))
 
 static const char *const var_names[] = { "c", NULL };
 enum { VAR_C, VAR_VARS_NB };
 
 typedef struct {
     const AVClass *class;
 
     /* coefficient factor expression */
     char *expr_str;
     AVExpr *expr;
     double var_values[VAR_VARS_NB];
 
     int pr_width, pr_height;    // width and height to process
     float sigma;                // used when no expression are st
     float th;                   // threshold (3*sigma)
     float color_dct[3][3];      // 3x3 DCT for color decorrelation
     float *cbuf[2][3];          // two planar rgb color buffers
     float *weights;             // dct coeff are cumulated with overlapping; these values are used for averaging
     int p_linesize;             // line sizes for color and weights
     int overlap;                // number of block overlapping pixels
     int step;                   // block step increment (BSIZE - overlap)
     DCTContext *dct, *idct;     // DCT and inverse DCT contexts
     float *block, *tmp_block;   // two BSIZE x BSIZE block buffers
 } DCTdnoizContext;
 
 #define OFFSET(x) offsetof(DCTdnoizContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 static const AVOption dctdnoiz_options[] = {
     { "sigma",   "set noise sigma constant",               OFFSET(sigma),    AV_OPT_TYPE_FLOAT,  {.dbl=0},            0, 999,          .flags = FLAGS },
     { "s",       "set noise sigma constant",               OFFSET(sigma),    AV_OPT_TYPE_FLOAT,  {.dbl=0},            0, 999,          .flags = FLAGS },
     { "overlap", "set number of block overlapping pixels", OFFSET(overlap),  AV_OPT_TYPE_INT,    {.i64=(1<<NBITS)-1}, 0, (1<<NBITS)-1, .flags = FLAGS },
     { "expr",    "set coefficient factor expression",      OFFSET(expr_str), AV_OPT_TYPE_STRING, {.str=NULL},                          .flags = FLAGS },
     { "e",       "set coefficient factor expression",      OFFSET(expr_str), AV_OPT_TYPE_STRING, {.str=NULL},                          .flags = FLAGS },
     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(dctdnoiz);
 
 static float *dct_block(DCTdnoizContext *ctx, const float *src, int src_linesize)
 {
     int x, y;
     float *column;
 
     for (y = 0; y < BSIZE; y++) {
         float *line = ctx->block;
 
         memcpy(line, src, BSIZE * sizeof(*line));
         src += src_linesize;
         av_dct_calc(ctx->dct, line);
 
         column = ctx->tmp_block + y;

         column[0] = line[0] * (1. / sqrt(BSIZE));
         column += BSIZE;
         for (x = 1; x < BSIZE; x++) {
             *column = line[x] * sqrt(2. / BSIZE);

             column += BSIZE;
         }
     }
 
     column = ctx->tmp_block;
     for (x = 0; x < BSIZE; x++) {
         av_dct_calc(ctx->dct, column);

         column[0] *= 1. / sqrt(BSIZE);
         for (y = 1; y < BSIZE; y++)
             column[y] *= sqrt(2. / BSIZE);

         column += BSIZE;
     }
 
     for (y = 0; y < BSIZE; y++)
         for (x = 0; x < BSIZE; x++)
             ctx->block[y*BSIZE + x] = ctx->tmp_block[x*BSIZE + y];
 
     return ctx->block;
 }
 
 static void idct_block(DCTdnoizContext *ctx, float *dst, int dst_linesize)
 {
     int x, y;
     float *block = ctx->block;
     float *tmp = ctx->tmp_block;
 
     for (y = 0; y < BSIZE; y++) {

         block[0] *= sqrt(BSIZE);
         for (x = 1; x < BSIZE; x++)
             block[x] *= 1./sqrt(2. / BSIZE);

         av_dct_calc(ctx->idct, block);
         block += BSIZE;
     }
 
     block = ctx->block;
     for (y = 0; y < BSIZE; y++) {

         tmp[0] = block[y] * sqrt(BSIZE);
         for (x = 1; x < BSIZE; x++)
             tmp[x] = block[x*BSIZE + y] * (1./sqrt(2. / BSIZE));

         av_dct_calc(ctx->idct, tmp);
         for (x = 0; x < BSIZE; x++)
             dst[x*dst_linesize + y] += tmp[x];
     }
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     DCTdnoizContext *s = ctx->priv;
     int i, x, y, bx, by, linesize, *iweights;
     const float dct_3x3[3][3] = {
         { 1./sqrt(3),  1./sqrt(3),  1./sqrt(3) },
         { 1./sqrt(2),           0, -1./sqrt(2) },
         { 1./sqrt(6), -2./sqrt(6),  1./sqrt(6) },
     };
     uint8_t rgba_map[4];
 
     ff_fill_rgba_map(rgba_map, inlink->format);
     for (y = 0; y < 3; y++)
         for (x = 0; x < 3; x++)
             s->color_dct[y][x] = dct_3x3[rgba_map[y]][rgba_map[x]];
 
     s->pr_width  = inlink->w - (inlink->w - BSIZE) % s->step;

     s->pr_height = inlink->h - (inlink->h - BSIZE) % s->step;

     if (s->pr_width != inlink->w)
         av_log(ctx, AV_LOG_WARNING, "The last %d horizontal pixels won't be denoised\n",
                inlink->w - s->pr_width);
     if (s->pr_height != inlink->h)
         av_log(ctx, AV_LOG_WARNING, "The last %d vertical pixels won't be denoised\n",
                inlink->h - s->pr_height);
 
     s->p_linesize = linesize = FFALIGN(s->pr_width, 32);
     for (i = 0; i < 2; i++) {
         s->cbuf[i][0] = av_malloc(linesize * s->pr_height * sizeof(*s->cbuf[i][0]));
         s->cbuf[i][1] = av_malloc(linesize * s->pr_height * sizeof(*s->cbuf[i][1]));
         s->cbuf[i][2] = av_malloc(linesize * s->pr_height * sizeof(*s->cbuf[i][2]));
         if (!s->cbuf[i][0] || !s->cbuf[i][1] || !s->cbuf[i][2])
             return AVERROR(ENOMEM);
     }
 
     s->weights = av_malloc(s->pr_height * linesize * sizeof(*s->weights));
     if (!s->weights)
         return AVERROR(ENOMEM);
     iweights = av_calloc(s->pr_height, linesize * sizeof(*iweights));
     if (!iweights)
         return AVERROR(ENOMEM);
     for (y = 0; y < s->pr_height - BSIZE + 1; y += s->step)
         for (x = 0; x < s->pr_width - BSIZE + 1; x += s->step)
             for (by = 0; by < BSIZE; by++)
                 for (bx = 0; bx < BSIZE; bx++)
                     iweights[(y + by)*linesize + x + bx]++;
     for (y = 0; y < s->pr_height; y++)
         for (x = 0; x < s->pr_width; x++)
             s->weights[y*linesize + x] = 1. / iweights[y*linesize + x];
     av_free(iweights);
 
     return 0;
 }
 
 static av_cold int init(AVFilterContext *ctx)
 {
     DCTdnoizContext *s = ctx->priv;
 
     if (s->expr_str) {
         int ret = av_expr_parse(&s->expr, s->expr_str, var_names,
                                 NULL, NULL, NULL, NULL, 0, ctx);
         if (ret < 0)
             return ret;
     }
 
     s->th   = s->sigma * 3.;
     s->step = BSIZE - s->overlap;
     s->dct  = av_dct_init(NBITS, DCT_II);
     s->idct = av_dct_init(NBITS, DCT_III);
     s->block     = av_malloc(BSIZE * BSIZE * sizeof(*s->block));
     s->tmp_block = av_malloc(BSIZE * BSIZE * sizeof(*s->tmp_block));
 
     if (!s->dct || !s->idct || !s->tmp_block || !s->block)
         return AVERROR(ENOMEM);
 
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_BGR24, AV_PIX_FMT_RGB24,
         AV_PIX_FMT_NONE
     };
     ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
     return 0;
 }
 
 static void color_decorrelation(float dct3ch[3][3], float **dst, int dst_linesize,
                                 const uint8_t *src, int src_linesize, int w, int h)
 {
     int x, y;
     float *dstp_r = dst[0];
     float *dstp_g = dst[1];
     float *dstp_b = dst[2];
 
     for (y = 0; y < h; y++) {
         const uint8_t *srcp = src;
 
         for (x = 0; x < w; x++) {
             dstp_r[x] = srcp[0] * dct3ch[0][0] + srcp[1] * dct3ch[0][1] + srcp[2] * dct3ch[0][2];
             dstp_g[x] = srcp[0] * dct3ch[1][0] + srcp[1] * dct3ch[1][1] + srcp[2] * dct3ch[1][2];
             dstp_b[x] = srcp[0] * dct3ch[2][0] + srcp[1] * dct3ch[2][1] + srcp[2] * dct3ch[2][2];
             srcp += 3;
         }
         src += src_linesize;
         dstp_r += dst_linesize;
         dstp_g += dst_linesize;
         dstp_b += dst_linesize;
     }
 }
 
 static void color_correlation(float dct3ch[3][3], uint8_t *dst, int dst_linesize,
                               float **src, int src_linesize, int w, int h)
 {
     int x, y;
     const float *src_r = src[0];
     const float *src_g = src[1];
     const float *src_b = src[2];
 
     for (y = 0; y < h; y++) {
         uint8_t *dstp = dst;
 
         for (x = 0; x < w; x++) {
             dstp[0] = av_clip_uint8(src_r[x] * dct3ch[0][0] + src_g[x] * dct3ch[1][0] + src_b[x] * dct3ch[2][0]);
             dstp[1] = av_clip_uint8(src_r[x] * dct3ch[0][1] + src_g[x] * dct3ch[1][1] + src_b[x] * dct3ch[2][1]);
             dstp[2] = av_clip_uint8(src_r[x] * dct3ch[0][2] + src_g[x] * dct3ch[1][2] + src_b[x] * dct3ch[2][2]);
             dstp += 3;
         }
         dst += dst_linesize;
         src_r += src_linesize;
         src_g += src_linesize;
         src_b += src_linesize;
     }
 }
 
 static void filter_plane(AVFilterContext *ctx,
                          float *dst, int dst_linesize,
                          const float *src, int src_linesize,
                          int w, int h)
 {
     int x, y, bx, by;
     DCTdnoizContext *s = ctx->priv;
     float *dst0 = dst;
     const float *weights = s->weights;
 
     // reset block sums
     memset(dst, 0, h * dst_linesize * sizeof(*dst));
 
     // block dct sums
     for (y = 0; y < h - BSIZE + 1; y += s->step) {
         for (x = 0; x < w - BSIZE + 1; x += s->step) {
             float *ftb = dct_block(s, src + x, src_linesize);
 
             if (s->expr) {
                 for (by = 0; by < BSIZE; by++) {
                     for (bx = 0; bx < BSIZE; bx++) {
                         s->var_values[VAR_C] = FFABS(*ftb);
                         *ftb++ *= av_expr_eval(s->expr, s->var_values, s);
                     }
                 }
             } else {
                 for (by = 0; by < BSIZE; by++) {
                     for (bx = 0; bx < BSIZE; bx++) {
                         if (FFABS(*ftb) < s->th)
                             *ftb = 0;
                         ftb++;
                     }
                 }
             }
             idct_block(s, dst + x, dst_linesize);
         }
         src += s->step * src_linesize;
         dst += s->step * dst_linesize;
     }
 
     // average blocks
     dst = dst0;
     for (y = 0; y < h; y++) {
         for (x = 0; x < w; x++)
             dst[x] *= weights[x];
         dst += dst_linesize;
         weights += dst_linesize;
     }
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     AVFilterContext *ctx = inlink->dst;
     DCTdnoizContext *s = ctx->priv;
     AVFilterLink *outlink = inlink->dst->outputs[0];
     int direct, plane;
     AVFrame *out;
 
     if (av_frame_is_writable(in)) {
         direct = 1;
         out = in;
     } else {
         direct = 0;
         out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
         if (!out) {
             av_frame_free(&in);
             return AVERROR(ENOMEM);
         }
         av_frame_copy_props(out, in);
     }
 
     color_decorrelation(s->color_dct, s->cbuf[0], s->p_linesize,
                         in->data[0], in->linesize[0], s->pr_width, s->pr_height);
     for (plane = 0; plane < 3; plane++)
         filter_plane(ctx, s->cbuf[1][plane], s->p_linesize,
                           s->cbuf[0][plane], s->p_linesize,
                           s->pr_width, s->pr_height);
     color_correlation(s->color_dct, out->data[0], out->linesize[0],
                       s->cbuf[1], s->p_linesize, s->pr_width, s->pr_height);
 
     if (!direct) {
         int y;
         uint8_t *dst = out->data[0];
         const uint8_t *src = in->data[0];
         const int dst_linesize = out->linesize[0];
         const int src_linesize = in->linesize[0];
         const int hpad = (inlink->w - s->pr_width) * 3;
         const int vpad = (inlink->h - s->pr_height);
 
         if (hpad) {
             uint8_t       *dstp = dst + s->pr_width * 3;
             const uint8_t *srcp = src + s->pr_width * 3;
 
             for (y = 0; y < s->pr_height; y++) {
                 memcpy(dstp, srcp, hpad);
                 dstp += dst_linesize;
                 srcp += src_linesize;
             }
         }
         if (vpad) {
             uint8_t       *dstp = dst + s->pr_height * dst_linesize;
             const uint8_t *srcp = src + s->pr_height * src_linesize;
 
             for (y = 0; y < vpad; y++) {
                 memcpy(dstp, srcp, inlink->w * 3);
                 dstp += dst_linesize;
                 srcp += src_linesize;
             }
         }
 
         av_frame_free(&in);
     }
 
     return ff_filter_frame(outlink, out);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     int i;
     DCTdnoizContext *s = ctx->priv;
 
     av_dct_end(s->dct);
     av_dct_end(s->idct);
     av_free(s->block);
     av_free(s->tmp_block);
     av_free(s->weights);
     for (i = 0; i < 2; i++) {
         av_free(s->cbuf[i][0]);
         av_free(s->cbuf[i][1]);
         av_free(s->cbuf[i][2]);
     }
     av_expr_free(s->expr);
 }
 
 static const AVFilterPad dctdnoiz_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
         .config_props = config_input,
     },
     { NULL }
 };
 
 static const AVFilterPad dctdnoiz_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 
 AVFilter avfilter_vf_dctdnoiz = {
     .name          = "dctdnoiz",
     .description   = NULL_IF_CONFIG_SMALL("Denoise frames using 2D DCT."),
     .priv_size     = sizeof(DCTdnoizContext),
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,
     .inputs        = dctdnoiz_inputs,
     .outputs       = dctdnoiz_outputs,
     .priv_class    = &dctdnoiz_class,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
 };