ref: e6bfdce30df73cd2f86c16d010b5430ed14ed090
parent: 76d9afc349fec0d1edc4d674daaca89b6c8c9c90
author: sdeng <sdeng@google.com>
date: Mon Nov 18 06:33:22 EST 2019
Use a better model for tune=ssim
Comparing to the baseline tune=ssim, the average gains are
PSNR -0.55, SSIM -0.30, MS-SSIM -0.98, VMAF -1.26
Details: (150f VBR)
PSNR SSIM MS-SSIM VMAF
Lowres -1.347 0.291 -0.307 -1.291
Midres -0.628 -0.329 -1.011 -2.173
Hdres 0.781 -0.656 -1.319 0.210
Ugc360p -2.695 -0.972 -1.503 -4.055
Lowres_bd10 0.074 0.196 -0.623 -0.835
Midres_bd10 0.517 -0.327 -1.124 0.566
Change-Id: Ie034eaedf20e1fe843921cafbb3b7ad9a2bc89d1
--- a/vp9/encoder/vp9_encoder.c
+++ b/vp9/encoder/vp9_encoder.c
@@ -4863,17 +4863,6 @@
}
}
-// Implementation and modifications of C. Yeo, H. L. Tan, and Y. H. Tan, "On
-// rate distortion optimization using SSIM," Circuits and Systems for Video
-// Technology, IEEE Transactions on, vol. 23, no. 7, pp. 1170-1181, 2013.
-// SSIM_VAR_SCALE defines the strength of the bias towards SSIM in RDO.
-// Some sample values are:
-// (for midres test set)
-// SSIM_VAR_SCALE avg_psnr ssim ms_ssim
-// 8.0 9.421 -5.537 -6.898
-// 16.0 4.703 -5.378 -6.238
-// 32.0 1.929 -4.308 -4.807
-#define SSIM_VAR_SCALE 16.0
static void set_mb_ssim_rdmult_scaling(VP9_COMP *cpi) {VP9_COMMON *cm = &cpi->common;
ThreadData *td = &cpi->td;
@@ -4890,8 +4879,6 @@
double log_sum = 0.0;
int row, col;
- 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) { for (col = 0; col < num_cols; ++col) {@@ -4925,7 +4912,10 @@
}
}
var = var / num_of_var / 64.0;
- var = 2.0 * var + c2;
+
+ // Curve fitting with an exponential model on all 16x16 blocks from the
+ // Midres dataset.
+ var = 67.035434 * (1 - exp(-0.0021489 * var)) + 17.492222;
cpi->mi_ssim_rdmult_scaling_factors[index] = var;
log_sum += log(var);
}