shithub: libvpx

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Change parameters for highbd tune=ssim

With this CL:
             PSNR   SSIM    MS-SSIM
lowres_10bd  2.8    -5.6    -6.5
midres_10bd  2.6    -5.6    -6.3

Before this CL:
             PSNR   SSIM    MS-SSIM
lowres_10bd  6.1    -6.5    -7.7
midres_10bd  6.2    -6.0    -7.2

Change-Id: Iad0ad96d55ad140db00ce86c34ab85461cd963eb

--- a/vp9/encoder/vp9_encoder.c

+++ b/vp9/encoder/vp9_encoder.c

@@ -4783,18 +4783,7 @@

   double log_sum = 0.0;

   int row, col;

-#if CONFIG_VP9_HIGHBITDEPTH

-  double c2;

-  if (xd->bd == 10) {

-    c2 = 941.8761;  // (.03*1023)^2

-  } else if (xd->bd == 12) {

-    c2 = 15092.1225;  // (.03*4095)^2

-  } else {

-    c2 = 58.5225;  // (.03*255)^2

-  }

-#else

-  const double c2 = 58.5225;  // (.03*255)^2

-#endif

+  const double c2 = 58.5225 * SSIM_VAR_SCALE;  // 58.5225 = (.03*255)^2

   // Loop through each 64x64 block.

   for (row = 0; row < num_rows; ++row) {

@@ -4817,18 +4806,18 @@

           // In order to make SSIM_VAR_SCALE in a same scale for both 8 bit

           // and high bit videos, the variance needs to be divided by 2.0 or

           // 64.0 separately.

+          // TODO(sdeng): need to tune for 12bit videos.

 #if CONFIG_VP9_HIGHBITDEPTH

           if (cpi->Source->flags & YV12_FLAG_HIGHBITDEPTH)

-            var +=

-                vp9_high_get_sby_variance(cpi, &buf, BLOCK_8X8, xd->bd) / 2.0;

+            var += vp9_high_get_sby_variance(cpi, &buf, BLOCK_8X8, xd->bd);

           else

 #endif

-            var += vp9_get_sby_variance(cpi, &buf, BLOCK_8X8) / 64.0;

+            var += vp9_get_sby_variance(cpi, &buf, BLOCK_8X8);

           num_of_var += 1.0;

         }

       }

-      var = var / num_of_var / SSIM_VAR_SCALE;

+      var = var / num_of_var / 64.0;

       var = 2.0 * var + c2;

       cpi->mi_ssim_rdmult_scaling_factors[index] = var;

       log_sum += log(var);