shithub: libvpx

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vp9: Non-rd variance partition: add condition for 64x64 split.

Add stronger condition for splitting 64x64, for low noise content.
This reduces dragging artifact near moving head.

Little/no change in metrics on RTC set.

Change-Id: I39b38cfd20f2ece53ff49c2aaf76ba9f82761be1

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

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

@@ -795,7 +795,11 @@

   v16x16 vt2[16];

   int force_split[21];

   int avg_32x32;

+  int max_var_32x32 = 0;

+  int min_var_32x32 = INT_MAX;

+  int var_32x32;

   int avg_16x16[4];

+  NOISE_LEVEL noise_level = kLow;

   uint8_t *s;

   const uint8_t *d;

   int sp;

@@ -1038,6 +1042,9 @@

     // (64x64) level.

     if (!force_split[i + 1]) {

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

+      var_32x32 = vt.split[i].part_variances.none.variance;

+      max_var_32x32 = VPXMAX(var_32x32, max_var_32x32);

+      min_var_32x32 = VPXMIN(var_32x32, min_var_32x32);

       if (vt.split[i].part_variances.none.variance > thresholds[1] ||

           (!is_key_frame &&

            vt.split[i].part_variances.none.variance > (thresholds[1] >> 1) &&

@@ -1045,15 +1052,27 @@

         force_split[i + 1] = 1;

         force_split[0] = 1;

       }

-      avg_32x32 += vt.split[i].part_variances.none.variance;

+      avg_32x32 += var_32x32;

     }

   }

   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.

-    if (!is_key_frame && vt.part_variances.none.variance > (5 * avg_32x32) >> 4)

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

+    if (!is_key_frame && noise_level >= kMedium &&

+        vt.part_variances.none.variance > (5 * avg_32x32) >> 4)

+      force_split[0] = 1;

+    // Else if the maximum 32x32 variance minus the miniumum 32x32 variance in

+    // a 64x64 block is greater than threshold and the maximum 32x32 variance is

+    // above a miniumum threshold, then force the split of a 64x64 block

+    // Only check this for low noise.

+    else if (!is_key_frame && noise_level < kMedium &&

+             (max_var_32x32 - min_var_32x32) > 3 * (thresholds[0] >> 3) &&

+             max_var_32x32 > thresholds[0] >> 1)

       force_split[0] = 1;

   }