/*
  * Copyright (c) 2003-2013 Loren Merritt
  * Copyright (c) 2015 Paul B Mahol
  *
  * 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
  */
 
 /* Computes the Structural Similarity Metric between two video streams.
  * original algorithm:
  * Z. Wang, A. C. Bovik, H. R. Sheikh and E. P. Simoncelli,
  *   "Image quality assessment: From error visibility to structural similarity,"
  *   IEEE Transactions on Image Processing, vol. 13, no. 4, pp. 600-612, Apr. 2004.
  *
  * To improve speed, this implementation uses the standard approximation of
  * overlapped 8x8 block sums, rather than the original gaussian weights.
  */
 
 /*
  * @file
  * Caculate the SSIM between two input videos.
  */
 

 #include "libavutil/avstring.h"

 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
 #include "dualinput.h"
 #include "drawutils.h"
 #include "formats.h"
 #include "internal.h"

 #include "ssim.h"

 #include "video.h"
 
 typedef struct SSIMContext {
     const AVClass *class;
     FFDualInputContext dinput;
     FILE *stats_file;
     char *stats_file_str;
     int nb_components;
     uint64_t nb_frames;

     double ssim[4], ssim_total;

     char comps[4];

     float coefs[4];

     uint8_t rgba_map[4];
     int planewidth[4];
     int planeheight[4];
     int *temp;

     int is_rgb;

     SSIMDSPContext dsp;

 } SSIMContext;
 
 #define OFFSET(x) offsetof(SSIMContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
 static const AVOption ssim_options[] = {
     {"stats_file", "Set file where to store per-frame difference information", OFFSET(stats_file_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
     {"f",          "Set file where to store per-frame difference information", OFFSET(stats_file_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(ssim);
 
 static void set_meta(AVDictionary **metadata, const char *key, char comp, float d)
 {
     char value[128];
     snprintf(value, sizeof(value), "%0.2f", d);
     if (comp) {
         char key2[128];
         snprintf(key2, sizeof(key2), "%s%c", key, comp);
         av_dict_set(metadata, key2, value, 0);
     } else {
         av_dict_set(metadata, key, value, 0);
     }
 }
 

 static void ssim_4x4xn(const uint8_t *main, ptrdiff_t main_stride,
                        const uint8_t *ref, ptrdiff_t ref_stride,

                        int (*sums)[4], int width)

 {
     int x, y, z;
 

     for (z = 0; z < width; z++) {

         uint32_t s1 = 0, s2 = 0, ss = 0, s12 = 0;
 
         for (y = 0; y < 4; y++) {
             for (x = 0; x < 4; x++) {
                 int a = main[x + y * main_stride];
                 int b = ref[x + y * ref_stride];
 
                 s1  += a;
                 s2  += b;
                 ss  += a*a;
                 ss  += b*b;
                 s12 += a*b;
             }
         }
 
         sums[z][0] = s1;
         sums[z][1] = s2;
         sums[z][2] = ss;
         sums[z][3] = s12;
         main += 4;
         ref += 4;
     }
 }
 
 static float ssim_end1(int s1, int s2, int ss, int s12)
 {
     static const int ssim_c1 = (int)(.01*.01*255*255*64 + .5);
     static const int ssim_c2 = (int)(.03*.03*255*255*64*63 + .5);
 
     int fs1 = s1;
     int fs2 = s2;
     int fss = ss;
     int fs12 = s12;
     int vars = fss * 64 - fs1 * fs1 - fs2 * fs2;
     int covar = fs12 * 64 - fs1 * fs2;
 
     return (float)(2 * fs1 * fs2 + ssim_c1) * (float)(2 * covar + ssim_c2)
          / ((float)(fs1 * fs1 + fs2 * fs2 + ssim_c1) * (float)(vars + ssim_c2));
 }
 

 static float ssim_endn(const int (*sum0)[4], const int (*sum1)[4], int width)

 {
     float ssim = 0.0;
     int i;
 

     for (i = 0; i < width; i++)

         ssim += ssim_end1(sum0[i][0] + sum0[i + 1][0] + sum1[i][0] + sum1[i + 1][0],
                           sum0[i][1] + sum0[i + 1][1] + sum1[i][1] + sum1[i + 1][1],
                           sum0[i][2] + sum0[i + 1][2] + sum1[i][2] + sum1[i + 1][2],
                           sum0[i][3] + sum0[i + 1][3] + sum1[i][3] + sum1[i + 1][3]);
     return ssim;
 }
 

 static float ssim_plane(SSIMDSPContext *dsp,
                         uint8_t *main, int main_stride,

                         uint8_t *ref, int ref_stride,
                         int width, int height, void *temp)
 {

     int z = 0, y;

     float ssim = 0.0;
     int (*sum0)[4] = temp;
     int (*sum1)[4] = sum0 + (width >> 2) + 3;
 
     width >>= 2;
     height >>= 2;
 
     for (y = 1; y < height; y++) {
         for (; z <= y; z++) {
             FFSWAP(void*, sum0, sum1);

             dsp->ssim_4x4_line(&main[4 * z * main_stride], main_stride,
                                &ref[4 * z * ref_stride], ref_stride,
                                sum0, width);

         }
 

         ssim += dsp->ssim_end_line((const int (*)[4])sum0, (const int (*)[4])sum1, width - 1);

     }
 
     return ssim / ((height - 1) * (width - 1));
 }
 
 static double ssim_db(double ssim, double weight)
 {

     return 10 * log10(weight / (weight - ssim));

 }
 
 static AVFrame *do_ssim(AVFilterContext *ctx, AVFrame *main,
                         const AVFrame *ref)
 {
     AVDictionary **metadata = avpriv_frame_get_metadatap(main);
     SSIMContext *s = ctx->priv;

     float c[4], ssimv = 0.0;

     int i;
 
     s->nb_frames++;
 

     for (i = 0; i < s->nb_components; i++) {

         c[i] = ssim_plane(&s->dsp, main->data[i], main->linesize[i],

                           ref->data[i], ref->linesize[i],
                           s->planewidth[i], s->planeheight[i], s->temp);

         ssimv += s->coefs[i] * c[i];
         s->ssim[i] += c[i];
     }
     for (i = 0; i < s->nb_components; i++) {
         int cidx = s->is_rgb ? s->rgba_map[i] : i;
         set_meta(metadata, "lavfi.ssim.", s->comps[i], c[cidx]);
     }
     s->ssim_total += ssimv;

 
     set_meta(metadata, "lavfi.ssim.All", 0, ssimv);

     set_meta(metadata, "lavfi.ssim.dB", 0, ssim_db(ssimv, 1.0));

 
     if (s->stats_file) {
         fprintf(s->stats_file, "n:%"PRId64" ", s->nb_frames);
 

         for (i = 0; i < s->nb_components; i++) {
             int cidx = s->is_rgb ? s->rgba_map[i] : i;
             fprintf(s->stats_file, "%c:%f ", s->comps[i], c[cidx]);
         }

         fprintf(s->stats_file, "All:%f (%f)\n", ssimv, ssim_db(ssimv, 1.0));

     }
 
     return main;
 }
 
 static av_cold int init(AVFilterContext *ctx)
 {
     SSIMContext *s = ctx->priv;
 

     if (s->stats_file_str) {
         if (!strcmp(s->stats_file_str, "-")) {
             s->stats_file = stdout;
         } else {
             s->stats_file = fopen(s->stats_file_str, "w");
             if (!s->stats_file) {
                 int err = AVERROR(errno);
                 char buf[128];
                 av_strerror(err, buf, sizeof(buf));
                 av_log(ctx, AV_LOG_ERROR, "Could not open stats file %s: %s\n",
                        s->stats_file_str, buf);
                 return err;
             }

         }
     }
 
     s->dinput.process = do_ssim;
     s->dinput.shortest = 1;
     s->dinput.repeatlast = 0;
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_GRAY8,
         AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV444P,
         AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
         AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
         AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ444P,
         AV_PIX_FMT_GBRP,
         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_ref(AVFilterLink *inlink)
 {
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     AVFilterContext *ctx  = inlink->dst;
     SSIMContext *s = ctx->priv;

     int sum = 0, i;

 
     s->nb_components = desc->nb_components;
 
     if (ctx->inputs[0]->w != ctx->inputs[1]->w ||
         ctx->inputs[0]->h != ctx->inputs[1]->h) {
         av_log(ctx, AV_LOG_ERROR, "Width and height of input videos must be same.\n");
         return AVERROR(EINVAL);
     }
     if (ctx->inputs[0]->format != ctx->inputs[1]->format) {
         av_log(ctx, AV_LOG_ERROR, "Inputs must be of same pixel format.\n");
         return AVERROR(EINVAL);
     }
 

     s->is_rgb = ff_fill_rgba_map(s->rgba_map, inlink->format) >= 0;
     s->comps[0] = s->is_rgb ? 'R' : 'Y';
     s->comps[1] = s->is_rgb ? 'G' : 'U';
     s->comps[2] = s->is_rgb ? 'B' : 'V';

     s->comps[3] = 'A';
 

     s->planeheight[1] = s->planeheight[2] = AV_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);

     s->planeheight[0] = s->planeheight[3] = inlink->h;

     s->planewidth[1]  = s->planewidth[2]  = AV_CEIL_RSHIFT(inlink->w, desc->log2_chroma_w);

     s->planewidth[0]  = s->planewidth[3]  = inlink->w;

     for (i = 0; i < s->nb_components; i++)
         sum += s->planeheight[i] * s->planewidth[i];
     for (i = 0; i < s->nb_components; i++)
         s->coefs[i] = (double) s->planeheight[i] * s->planewidth[i] / sum;

 
     s->temp = av_malloc((2 * inlink->w + 12) * sizeof(*s->temp));
     if (!s->temp)
         return AVERROR(ENOMEM);
 

     s->dsp.ssim_4x4_line = ssim_4x4xn;
     s->dsp.ssim_end_line = ssim_endn;
     if (ARCH_X86)
         ff_ssim_init_x86(&s->dsp);
 

     return 0;
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     SSIMContext *s = ctx->priv;
     AVFilterLink *mainlink = ctx->inputs[0];
     int ret;
 
     outlink->w = mainlink->w;
     outlink->h = mainlink->h;
     outlink->time_base = mainlink->time_base;
     outlink->sample_aspect_ratio = mainlink->sample_aspect_ratio;
     outlink->frame_rate = mainlink->frame_rate;
 
     if ((ret = ff_dualinput_init(ctx, &s->dinput)) < 0)
         return ret;
 
     return 0;
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
 {
     SSIMContext *s = inlink->dst->priv;
     return ff_dualinput_filter_frame(&s->dinput, inlink, buf);
 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     SSIMContext *s = outlink->src->priv;
     return ff_dualinput_request_frame(&s->dinput, outlink);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     SSIMContext *s = ctx->priv;
 
     if (s->nb_frames > 0) {

         char buf[256];
         int i;
         buf[0] = 0;
         for (i = 0; i < s->nb_components; i++) {
             int c = s->is_rgb ? s->rgba_map[i] : i;

             av_strlcatf(buf, sizeof(buf), " %c:%f (%f)", s->comps[i], s->ssim[c] / s->nb_frames,
                         ssim_db(s->ssim[c], s->nb_frames));

         }

         av_log(ctx, AV_LOG_INFO, "SSIM%s All:%f (%f)\n", buf,
                s->ssim_total / s->nb_frames, ssim_db(s->ssim_total, s->nb_frames));

     }
 
     ff_dualinput_uninit(&s->dinput);
 

     if (s->stats_file && s->stats_file != stdout)

         fclose(s->stats_file);
 
     av_freep(&s->temp);
 }
 
 static const AVFilterPad ssim_inputs[] = {
     {
         .name         = "main",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
     },{
         .name         = "reference",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
         .config_props = config_input_ref,
     },
     { NULL }
 };
 
 static const AVFilterPad ssim_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output,
         .request_frame = request_frame,
     },
     { NULL }
 };
 
 AVFilter ff_vf_ssim = {
     .name          = "ssim",
     .description   = NULL_IF_CONFIG_SMALL("Calculate the SSIM between two video streams."),
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,
     .priv_size     = sizeof(SSIMContext),
     .priv_class    = &ssim_class,
     .inputs        = ssim_inputs,
     .outputs       = ssim_outputs,
 };