Add functions to build SSIM scaling factors
In tune=ssim mode, we need to scale rdmult based on the variance
of the current block. This CL adds the data structure and functions
to build the SSIM scaling factor array.
Change-Id: I28b3d27115ff9608b444b4045ee4fc481fc09632
diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index 2b4245b..035bc4f 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -537,6 +537,9 @@
aom_free(cpi->active_map.map);
cpi->active_map.map = NULL;
+ aom_free(cpi->ssim_rdmult_scaling_factors);
+ cpi->ssim_rdmult_scaling_factors = NULL;
+
aom_free(cpi->td.mb.above_pred_buf);
cpi->td.mb.above_pred_buf = NULL;
@@ -2764,6 +2767,17 @@
av1_set_speed_features_framesize_independent(cpi, oxcf->speed);
av1_set_speed_features_framesize_dependent(cpi, oxcf->speed);
+ {
+ const int bsize = BLOCK_16X16;
+ const int w = mi_size_wide[bsize];
+ const int h = mi_size_high[bsize];
+ const int num_cols = (cm->mi_cols + w - 1) / w;
+ const int num_rows = (cm->mi_rows + h - 1) / h;
+ CHECK_MEM_ERROR(cm, cpi->ssim_rdmult_scaling_factors,
+ aom_calloc(num_rows * num_cols,
+ sizeof(*cpi->ssim_rdmult_scaling_factors)));
+ }
+
for (int frame = 0; frame < MAX_LENGTH_TPL_FRAME_STATS; ++frame) {
int mi_cols = ALIGN_POWER_OF_TWO(cm->mi_cols, MAX_MIB_SIZE_LOG2);
int mi_rows = ALIGN_POWER_OF_TWO(cm->mi_rows, MAX_MIB_SIZE_LOG2);
@@ -4957,6 +4971,85 @@
}
}
+// 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.
+#define SSIM_VAR_SCALE 16.0
+static void set_mb_ssim_rdmult_scaling(AV1_COMP *cpi) {
+ AV1_COMMON *cm = &cpi->common;
+ ThreadData *td = &cpi->td;
+ MACROBLOCK *x = &td->mb;
+ MACROBLOCKD *xd = &x->e_mbd;
+ uint8_t *y_buffer = cpi->source->y_buffer;
+ const int y_stride = cpi->source->y_stride;
+ const int block_size = BLOCK_16X16;
+
+ const int num_mi_w = mi_size_wide[block_size];
+ const int num_mi_h = mi_size_high[block_size];
+ const int num_cols = (cm->mi_cols + num_mi_w - 1) / num_mi_w;
+ const int num_rows = (cm->mi_rows + num_mi_h - 1) / num_mi_h;
+ double log_sum = 0.0;
+ int row, col;
+ const int use_hbd = cpi->source->flags & YV12_FLAG_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
+ }
+
+ // Loop through each 16x16 block.
+ for (row = 0; row < num_rows; ++row) {
+ for (col = 0; col < num_cols; ++col) {
+ int mi_row, mi_col;
+ double var = 0.0, num_of_var = 0.0;
+ const int index = row * num_cols + col;
+
+ // Loop through each 8x8 block.
+ for (mi_row = row * num_mi_h;
+ mi_row < cm->mi_rows && mi_row < (row + 1) * num_mi_h; mi_row += 2) {
+ for (mi_col = col * num_mi_w;
+ mi_col < cm->mi_cols && mi_col < (col + 1) * num_mi_w;
+ mi_col += 2) {
+ struct buf_2d buf;
+ const int row_offset_y = mi_row << 2;
+ const int col_offset_y = mi_col << 2;
+
+ buf.buf = y_buffer + row_offset_y * y_stride + col_offset_y;
+ buf.stride = y_stride;
+
+ if (use_hbd) {
+ var += av1_high_get_sby_perpixel_variance(cpi, &buf, BLOCK_8X8,
+ xd->bd);
+ } else {
+ var += av1_get_sby_perpixel_variance(cpi, &buf, BLOCK_8X8);
+ }
+
+ num_of_var += 1.0;
+ }
+ }
+ var = var / num_of_var / SSIM_VAR_SCALE;
+ var = 2.0 * var + c2;
+ cpi->ssim_rdmult_scaling_factors[index] = var;
+ log_sum += log(var);
+ }
+ }
+ log_sum = exp(log_sum / (double)(num_rows * num_cols));
+
+ for (row = 0; row < num_rows; ++row) {
+ for (col = 0; col < num_cols; ++col) {
+ const int index = row * num_cols + col;
+ cpi->ssim_rdmult_scaling_factors[index] /= log_sum;
+ }
+ }
+
+ (void)xd;
+}
+
static int encode_frame_to_data_rate(AV1_COMP *cpi, size_t *size,
uint8_t *dest) {
AV1_COMMON *const cm = &cpi->common;
@@ -5086,6 +5179,8 @@
}
}
+ if (oxcf->tuning == AOM_TUNE_SSIM) set_mb_ssim_rdmult_scaling(cpi);
+
aom_clear_system_state();
#if CONFIG_INTERNAL_STATS
diff --git a/av1/encoder/encoder.h b/av1/encoder/encoder.h
index 0d7ff00..7336e87 100644
--- a/av1/encoder/encoder.h
+++ b/av1/encoder/encoder.h
@@ -1020,6 +1020,8 @@
// whether any no-zero delta_q was actually used
int deltaq_used;
+
+ double *ssim_rdmult_scaling_factors;
} AV1_COMP;
typedef struct {
