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);
 
     compute_images_mse((const uint8_t **)main->data, main->linesize,
                        (const uint8_t **)ref->data, ref->linesize,
                        main->width, main->height, s->desc, comp_mse);
 
     for (j = 0; j < s->desc->nb_components; j++)
         mse += comp_mse[j];
     mse /= s->desc->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->desc->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->desc->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->desc->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_GBRP, AV_PIX_FMT_GBRAP,
         AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV422P,
         AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,
         AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ422P,
         AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ411P,
         AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
         AV_PIX_FMT_NONE
     };
 
     ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
     return 0;
 }
 
 static int config_input_ref(AVFilterLink *inlink)
 {
     AVFilterContext *ctx  = inlink->dst;
     PSNRContext *s = ctx->priv;
     int j;
 
     s->desc = av_pix_fmt_desc_get(inlink->format);
     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 heigth 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_YUV410P:
     case AV_PIX_FMT_YUV411P:
     case AV_PIX_FMT_YUV420P:
     case AV_PIX_FMT_YUV422P:
     case AV_PIX_FMT_YUV440P:
     case AV_PIX_FMT_YUV444P:
     case AV_PIX_FMT_YUVA420P:
     case AV_PIX_FMT_YUVA422P:
     case AV_PIX_FMT_YUVA444P:
         s->max[0] = 235;
         s->max[3] = 255;
         s->max[1] = s->max[2] = 240;
         break;
     default:
         s->max[0] = s->max[1] = s->max[2] = s->max[3] = 255;
     }
 
     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->desc->nb_components; j++)
         s->average_max += s->max[j];
     s->average_max /= s->desc->nb_components;
 
     return 0;
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     AVFilterLink *mainlink = ctx->inputs[0];
 
     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;
 
     return 0;
 }
 
 static int filter_frame_main(AVFilterLink *inlink, AVFrame *inpicref)
 {
     PSNRContext *s = inlink->dst->priv;
     return ff_dualinput_filter_frame_main(&s->dinput, inlink, inpicref);
 }
 
 static int filter_frame_ref(AVFilterLink *inlink, AVFrame *inpicref)
 {
     PSNRContext *s = inlink->dst->priv;
     return ff_dualinput_filter_frame_second(&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_main,
     },{
         .name             = "reference",
         .type             = AVMEDIA_TYPE_VIDEO,
         .filter_frame     = filter_frame_ref,
         .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 avfilter_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,
 };