shithub: libvpx

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vp9-rtc: Adjustments for base layer in screen.

On scene/content changes for base layer of screen:
reduce 32x32 split threshold, bias rdcost for flat
blocks if sse_y is non-zero, and avoid early exit on
intra-check.

Reduce artifacts in scroll content.

Change-Id: I144357a61462351173af900e0b8a47dac4aad6ca

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

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

@@ -1352,6 +1352,11 @@

   } else {

     set_vbp_thresholds(cpi, thresholds, cm->base_qindex, content_state);

   }

+  // Decrease 32x32 split threshold for screen on base layer, for scene

+  // change/high motion frames.

+  if (cpi->oxcf.content == VP9E_CONTENT_SCREEN &&

+      cpi->svc.spatial_layer_id == 0 && force_64_split)

+    thresholds[1] = 3 * thresholds[1] >> 2;

   // For non keyframes, disable 4x4 average for low resolution when speed = 8

   threshold_4x4avg = (cpi->oxcf.speed < 8) ? thresholds[1] << 1 : INT64_MAX;

--- a/vp9/encoder/vp9_pickmode.c

+++ b/vp9/encoder/vp9_pickmode.c

@@ -2337,7 +2337,8 @@

     // Skipping checking: test to see if this block can be reconstructed by

     // prediction only.

-    if (cpi->allow_encode_breakout && !xd->lossless && !scene_change_detected) {

+    if (cpi->allow_encode_breakout && !xd->lossless && !scene_change_detected &&

+        !svc->high_num_blocks_with_motion) {

       encode_breakout_test(cpi, x, bsize, mi_row, mi_col, ref_frame, this_mode,

                            var_y, sse_y, yv12_mb, &this_rdc.rate,

                            &this_rdc.dist, flag_preduv_computed);

@@ -2348,6 +2349,15 @@

       }

     }

+    // On spatially flat blocks for screne content: bias against zero-last

+    // if the sse_y is non-zero. Only on scene change or high motion frames.

+    if (cpi->oxcf.content == VP9E_CONTENT_SCREEN &&

+        (scene_change_detected || svc->high_num_blocks_with_motion) &&

+        ref_frame == LAST_FRAME && frame_mv[this_mode][ref_frame].as_int == 0 &&

+        svc->spatial_layer_id == 0 && x->source_variance == 0 && sse_y > 0) {

+      this_rdc.rdcost = this_rdc.rdcost << 2;

+    }

+

 #if CONFIG_VP9_TEMPORAL_DENOISING

     if (cpi->oxcf.noise_sensitivity > 0 && denoise_svc_pickmode &&

         cpi->denoiser.denoising_level > kDenLowLow) {

@@ -2489,8 +2499,14 @@

                                       &rd_thresh_freq_fact[mode_index])) ||

           (!cpi->sf.adaptive_rd_thresh_row_mt &&

            rd_less_than_thresh(best_rdc.rdcost, mode_rd_thresh,

-                               &rd_thresh_freq_fact[mode_index])))

-        continue;

+                               &rd_thresh_freq_fact[mode_index]))) {

+        // Avoid this early exit for screen on base layer, for scene

+        // changes or high motion frames.

+        if (cpi->oxcf.content != VP9E_CONTENT_SCREEN ||

+            svc->spatial_layer_id > 0 ||

+            (!scene_change_detected && !svc->high_num_blocks_with_motion))

+          continue;

+      }

       mi->mode = this_mode;

       mi->ref_frame[0] = INTRA_FRAME;