int nb_components;
     int planewidth[4];
     int planeheight[4];

 
     void (*compute_mse)(struct PSNRContext *s,
                         const uint8_t *m[4], const int ml[4],
                         const uint8_t *r[4], const int rl[4],
                         int w, int h, double mse[4]);

 } PSNRContext;
 
 #define OFFSET(x) offsetof(PSNRContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
 static const AVOption psnr_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(psnr);
 

 static inline unsigned pow2(unsigned base)

 {
     return base*base;
 }
 
 static inline double get_psnr(double mse, uint64_t nb_frames, int max)
 {
     return 10.0 * log(pow2(max) / (mse / nb_frames)) / log(10.0);
 }
 
 static inline

 void compute_images_mse(PSNRContext *s,
                         const uint8_t *main_data[4], const int main_linesizes[4],

                         const uint8_t *ref_data[4], const int ref_linesizes[4],

                         int w, int h, double mse[4])

 {
     int i, c, j;
 

     for (c = 0; c < s->nb_components; c++) {
         const int outw = s->planewidth[c];
         const int outh = s->planeheight[c];

         const uint8_t *main_line = main_data[c];
         const uint8_t *ref_line = ref_data[c];
         const int ref_linesize = ref_linesizes[c];
         const int main_linesize = main_linesizes[c];

         uint64_t m = 0;

 
         for (i = 0; i < outh; i++) {

             int m2 = 0;

             for (j = 0; j < outw; j++)

                 m2 += pow2(main_line[j] - ref_line[j]);
             m += m2;

             ref_line += ref_linesize;
             main_line += main_linesize;
         }

         mse[c] = m / (double)(outw * outh);
     }
 }
 
 static inline
 void compute_images_mse_16bit(PSNRContext *s,
                         const uint8_t *main_data[4], const int main_linesizes[4],
                         const uint8_t *ref_data[4], const int ref_linesizes[4],
                         int w, int h, double mse[4])
 {
     int i, c, j;
 
     for (c = 0; c < s->nb_components; c++) {
         const int outw = s->planewidth[c];
         const int outh = s->planeheight[c];
         const uint16_t *main_line = (uint16_t *)main_data[c];
         const uint16_t *ref_line = (uint16_t *)ref_data[c];
         const int ref_linesize = ref_linesizes[c] / 2;
         const int main_linesize = main_linesizes[c] / 2;
         uint64_t m = 0;
 
         for (i = 0; i < outh; i++) {
             for (j = 0; j < outw; j++)
                 m += pow2(main_line[j] - ref_line[j]);
             ref_line += ref_linesize;
             main_line += main_linesize;
         }
         mse[c] = m / (double)(outw * outh);

     }
 }
 

 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 AVFrame *do_psnr(AVFilterContext *ctx, AVFrame *main,
                         const AVFrame *ref)
 {
     PSNRContext *s = ctx->priv;
     double comp_mse[4], mse = 0;
     int j, c;
     AVDictionary **metadata = avpriv_frame_get_metadatap(main);
 

     s->compute_mse(s, (const uint8_t **)main->data, main->linesize,
                       (const uint8_t **)ref->data, ref->linesize,

                        main->width, main->height, comp_mse);

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

         mse += comp_mse[j];

     mse /= s->nb_components;

 
     s->min_mse = FFMIN(s->min_mse, mse);
     s->max_mse = FFMAX(s->max_mse, mse);
 
     s->mse += mse;
     s->nb_frames++;
 

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

         c = s->is_rgb ? s->rgba_map[j] : j;

         set_meta(metadata, "lavfi.psnr.mse.", s->comps[j], comp_mse[c]);
         set_meta(metadata, "lavfi.psnr.mse_avg", 0, mse);

         set_meta(metadata, "lavfi.psnr.psnr.", s->comps[j], get_psnr(comp_mse[c], 1, s->max[c]));
         set_meta(metadata, "lavfi.psnr.psnr_avg", 0, get_psnr(mse, 1, s->average_max));

     }
 
     if (s->stats_file) {
         fprintf(s->stats_file, "n:%"PRId64" mse_avg:%0.2f ", s->nb_frames, mse);

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

             c = s->is_rgb ? s->rgba_map[j] : j;
             fprintf(s->stats_file, "mse_%c:%0.2f ", s->comps[j], comp_mse[c]);
         }

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

             c = s->is_rgb ? s->rgba_map[j] : j;

             fprintf(s->stats_file, "psnr_%c:%0.2f ", s->comps[j],

                     get_psnr(comp_mse[c], 1, s->max[c]));
         }
         fprintf(s->stats_file, "\n");
     }
 
     return main;
 }
 
 static av_cold int init(AVFilterContext *ctx)
 {
     PSNRContext *s = ctx->priv;
 
     s->min_mse = +INFINITY;
     s->max_mse = -INFINITY;
 
     if (s->stats_file_str) {
         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_psnr;
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum PixelFormat pix_fmts[] = {

         AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY16,
 #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_YUVJ411P, AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
         AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ444P,
         AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRP9, AV_PIX_FMT_GBRP10,
         AV_PIX_FMT_GBRP12, AV_PIX_FMT_GBRP14, AV_PIX_FMT_GBRP16,
         AV_PIX_FMT_GBRAP, AV_PIX_FMT_GBRAP16,

         AV_PIX_FMT_NONE
     };
 
     ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
     return 0;
 }
 
 static int config_input_ref(AVFilterLink *inlink)
 {

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

     AVFilterContext *ctx  = inlink->dst;
     PSNRContext *s = ctx->priv;
     int j;
 

     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);
     }
 
     switch (inlink->format) {

     case AV_PIX_FMT_GRAY8:
     case AV_PIX_FMT_GRAY16:
     case AV_PIX_FMT_GBRP:
     case AV_PIX_FMT_GBRP9:
     case AV_PIX_FMT_GBRP10:
     case AV_PIX_FMT_GBRP12:
     case AV_PIX_FMT_GBRP14:
     case AV_PIX_FMT_GBRP16:
     case AV_PIX_FMT_GBRAP:
     case AV_PIX_FMT_GBRAP16:
     case AV_PIX_FMT_YUVJ411P:
     case AV_PIX_FMT_YUVJ420P:
     case AV_PIX_FMT_YUVJ422P:
     case AV_PIX_FMT_YUVJ440P:
     case AV_PIX_FMT_YUVJ444P:
         s->max[0] = (1 << (desc->comp[0].depth_minus1 + 1)) - 1;
         s->max[1] = (1 << (desc->comp[1].depth_minus1 + 1)) - 1;
         s->max[2] = (1 << (desc->comp[2].depth_minus1 + 1)) - 1;
         s->max[3] = (1 << (desc->comp[3].depth_minus1 + 1)) - 1;

         break;
     default:

         s->max[0] = 235 * (1 << (desc->comp[0].depth_minus1 - 7));
         s->max[1] = 240 * (1 << (desc->comp[1].depth_minus1 - 7));
         s->max[2] = 240 * (1 << (desc->comp[2].depth_minus1 - 7));
         s->max[3] = (1 << (desc->comp[3].depth_minus1 + 1)) - 1;

     }
 
     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';
 

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

         s->average_max += s->max[j];

     s->average_max /= s->nb_components;
 
     s->planeheight[1] = s->planeheight[2] = FF_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
     s->planeheight[0] = s->planeheight[3] = inlink->h;
     s->planewidth[1]  = s->planewidth[2]  = FF_CEIL_RSHIFT(inlink->w, desc->log2_chroma_w);
     s->planewidth[0]  = s->planewidth[3]  = inlink->w;

     s->compute_mse = desc->comp[0].depth_minus1 > 7 ? compute_images_mse_16bit : compute_images_mse;
 

     return 0;
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;

     PSNRContext *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 *inpicref)

 {
     PSNRContext *s = inlink->dst->priv;

     return ff_dualinput_filter_frame(&s->dinput, inlink, inpicref);

 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     PSNRContext *s = outlink->src->priv;
     return ff_dualinput_request_frame(&s->dinput, outlink);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     PSNRContext *s = ctx->priv;
 
     if (s->nb_frames > 0) {
         av_log(ctx, AV_LOG_INFO, "PSNR average:%0.2f min:%0.2f max:%0.2f\n",
                get_psnr(s->mse, s->nb_frames, s->average_max),
                get_psnr(s->max_mse, 1, s->average_max),
                get_psnr(s->min_mse, 1, s->average_max));
     }
 
     ff_dualinput_uninit(&s->dinput);
 
     if (s->stats_file)
         fclose(s->stats_file);
 }
 
 static const AVFilterPad psnr_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 psnr_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output,
         .request_frame = request_frame,
     },
     { NULL }
 };
 

 AVFilter ff_vf_psnr = {

     .name          = "psnr",
     .description   = NULL_IF_CONFIG_SMALL("Calculate the PSNR between two video streams."),
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,
     .priv_size     = sizeof(PSNRContext),
     .priv_class    = &psnr_class,
     .inputs        = psnr_inputs,
     .outputs       = psnr_outputs,

 };