shithub: libvpx

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vp9-svc: Fix to allow for 4x4 variance for low resolutions.

Change-Id: I3ec08e10d9ebf6d8b8a03004a320523f926e5cc4

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

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

@@ -680,9 +680,13 @@

   int64_t thresholds[4] = {cpi->vbp_thresholds[0], cpi->vbp_thresholds[1],

       cpi->vbp_thresholds[2], cpi->vbp_thresholds[3]};

+  // For the variance computation under SVC mode, we treat the frame as key if

+  // the reference (base layer frame) is key frame (i.e., is_key_frame == 1).

+  const int is_key_frame = (cm->frame_type == KEY_FRAME ||

+      (is_one_pass_cbr_svc(cpi) &&

+      cpi->svc.layer_context[cpi->svc.temporal_layer_id].is_key_frame));

   // Always use 4x4 partition for key frame.

-  const int is_key_frame = (cm->frame_type == KEY_FRAME);

-  const int use_4x4_partition = is_key_frame;

+  const int use_4x4_partition = cm->frame_type == KEY_FRAME;

   const int low_res = (cm->width <= 352 && cm->height <= 288);

   int variance4x4downsample[16];

@@ -708,8 +712,7 @@

   s = x->plane[0].src.buf;

   sp = x->plane[0].src.stride;

-  if (!is_key_frame && !(is_one_pass_cbr_svc(cpi) &&

-      cpi->svc.layer_context[cpi->svc.temporal_layer_id].is_key_frame)) {

+  if (!is_key_frame) {

     // In the case of spatial/temporal scalable coding, the assumption here is

     // that the temporal reference frame will always be of type LAST_FRAME.

     // TODO(marpan): If that assumption is broken, we need to revisit this code.

@@ -868,9 +871,7 @@

           }

         }

       }

-      // TODO(marpan): There is an issue with variance based on 4x4 average in

-      // svc mode, don't allow it for now.

-      if (is_key_frame || (low_res && !cpi->use_svc &&

+      if (is_key_frame || (low_res &&

           vt.split[i].split[j].part_variances.none.variance >

           (thresholds[1] << 1))) {

         force_split[split_index] = 0;