shithub: libvpx

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Fixes for key frame coding at speed 5.

Keep the same transform cutoff and partition selection
for speed 5 as in speeds >=6 (non-rd speed settings).

Existing setting for key frame at speed 5 allowed transform size
up to 32x32 on key frames, and did not allow for 4x4 block partition size.
This created more visual artifacts on first few frames.

avgPSNR/overallPSNR/SSIM gains of 0.2/0.7/0.8 for rtc_derf(low-res) set,
and 0/0.7/1.1 gains for rtc set.

Change-Id: I8c139ec6c9bb74e14b4ffbad5f12e94f18a59c0b

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

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

@@ -2885,8 +2885,7 @@

   if (xd->lossless)

     return ONLY_4X4;

   if (cpi->common.frame_type == KEY_FRAME &&

-      cpi->sf.use_nonrd_pick_mode &&

-      cpi->sf.partition_search_type == VAR_BASED_PARTITION)

+      cpi->sf.use_nonrd_pick_mode)

     return ALLOW_16X16;

   if (cpi->sf.tx_size_search_method == USE_LARGESTALL)

     return ALLOW_32X32;

@@ -3583,8 +3582,15 @@

                                INT64_MAX, td->pc_root);

         } else {

           choose_partitioning(cpi, tile_info, x, mi_row, mi_col);

-          nonrd_select_partition(cpi, td, tile_data, mi, tp, mi_row, mi_col,

-                                 BLOCK_64X64, 1, &dummy_rdc, td->pc_root);

+          // TODO(marpan): Seems like nonrd_select_partition does not support

+          // 4x4 partition. Since 4x4 is used on key frame, use this switch

+          // for now.

+          if (cm->frame_type == KEY_FRAME)

+            nonrd_use_partition(cpi, td, tile_data, mi, tp, mi_row, mi_col,

+                                BLOCK_64X64, 1, &dummy_rdc, td->pc_root);

+          else

+            nonrd_select_partition(cpi, td, tile_data, mi, tp, mi_row, mi_col,

+                                   BLOCK_64X64, 1, &dummy_rdc, td->pc_root);

         }

         break;