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

vp9/encoder/vp9_encodeframe.c

diff --git a/vp9/encoder/vp9_encodeframe.c b/vp9/encoder/vp9_encodeframe.c
index 7bccc82..b405975 100644
--- 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;