shithub: libvpx

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vp9: Nonrd variance partition: improve split to 16x16.

Add additional condition to split to 16x16, for resolutions <= 360p,
reduces dragging artifact near moving boundary.

Small/no change on RTC metrics.

Change-Id: I314694f2166435d918f74e7ab42f002b07f40dae

--- a/vp9/encoder/vp9_encodeframe.c

+++ b/vp9/encoder/vp9_encodeframe.c

@@ -978,6 +978,8 @@

   int min_var_32x32 = INT_MAX;

   int var_32x32;

   int avg_16x16[4];

+  int maxvar_16x16[4];

+  int minvar_16x16[4];

   int64_t threshold_4x4avg;

   NOISE_LEVEL noise_level = kLow;

   int content_state = 0;

@@ -1170,6 +1172,8 @@

     const int i2 = i << 2;

     force_split[i + 1] = 0;

     avg_16x16[i] = 0;

+    maxvar_16x16[i] = 0;

+    minvar_16x16[i] = INT_MAX;

     for (j = 0; j < 4; j++) {

       const int x16_idx = x32_idx + ((j & 1) << 4);

       const int y16_idx = y32_idx + ((j >> 1) << 4);

@@ -1186,6 +1190,10 @@

         fill_variance_tree(&vt.split[i].split[j], BLOCK_16X16);

         get_variance(&vt.split[i].split[j].part_variances.none);

         avg_16x16[i] += vt.split[i].split[j].part_variances.none.variance;

+        if (vt.split[i].split[j].part_variances.none.variance < minvar_16x16[i])

+          minvar_16x16[i] = vt.split[i].split[j].part_variances.none.variance;

+        if (vt.split[i].split[j].part_variances.none.variance > maxvar_16x16[i])

+          maxvar_16x16[i] = vt.split[i].split[j].part_variances.none.variance;

         if (vt.split[i].split[j].part_variances.none.variance > thresholds[2]) {

           // 16X16 variance is above threshold for split, so force split to 8x8

           // for this 16x16 block (this also forces splits for upper levels).

@@ -1230,6 +1238,8 @@

       }

     }

   }

+  if (cpi->noise_estimate.enabled)

+    noise_level = vp9_noise_estimate_extract_level(&cpi->noise_estimate);

   // Fill the rest of the variance tree by summing split partition values.

   avg_32x32 = 0;

   for (i = 0; i < 4; i++) {

@@ -1265,6 +1275,11 @@

            vt.split[i].part_variances.none.variance > (avg_16x16[i] >> 1))) {

         force_split[i + 1] = 1;

         force_split[0] = 1;

+      } else if (!is_key_frame && noise_level < kLow && cm->height <= 360 &&

+                 (maxvar_16x16[i] - minvar_16x16[i]) > (thresholds[1] >> 1) &&

+                 maxvar_16x16[i] > thresholds[1]) {

+        force_split[i + 1] = 1;

+        force_split[0] = 1;

       }

       avg_32x32 += var_32x32;

     }

@@ -1272,8 +1287,6 @@

   if (!force_split[0]) {

     fill_variance_tree(&vt, BLOCK_64X64);

     get_variance(&vt.part_variances.none);

-    if (cpi->noise_estimate.enabled)

-      noise_level = vp9_noise_estimate_extract_level(&cpi->noise_estimate);

     // If variance of this 64x64 block is above (some threshold of) the average

     // variance over the sub-32x32 blocks, then force this block to split.

     // Only checking this for noise level >= medium for now.