Do one level less of transform search for large blocks

If block size is larger than 32x32, search transform size for one level
less than the other blocks.

This mainly affects speed 0 and 1, as speed >= 2 uses largest transform
size(except for keyframes and alt-ref frames).

Compression(negative means gain):
        speed 0     speed 1
lowres  -0.007%       0.00%
midres   0.023%     -0.011%
hdres    0.002%     -0.016%

Encoder speed:
Tested on crowd_run_1080p 30 frames
Fixed QP = 30, speed 0: 582.5s -> 564.6s
               speed 1:  75.0s ->  73.3s

Change-Id: I46622efafe0e88d502efa1480a5324ead1d1e8d0

diff --git a/vp9/encoder/vp9_rdopt.c b/vp9/encoder/vp9_rdopt.c
index f753cf6ab7ec2adfdfa324067c4915dd2fba6fd1..0d93d2bd66b7cfd508055e5ba15ddf25c475f341 100644 (file)
--- a/vp9/encoder/vp9_rdopt.c
+++ b/vp9/encoder/vp9_rdopt.c
@@ -859,6 +859,7 @@ static void choose_tx_size_from_rd(VP9_COMP *cpi, MACROBLOCK *x, int *rate,
   if (cm->tx_mode == TX_MODE_SELECT) {
     start_tx = max_tx_size;
     end_tx = VPXMAX(start_tx - cpi->sf.tx_size_search_depth, 0);
+    if (bs > BLOCK_32X32) end_tx = VPXMIN(end_tx + 1, start_tx);
   } else {
     TX_SIZE chosen_tx_size =
         VPXMIN(max_tx_size, tx_mode_to_biggest_tx_size[cm->tx_mode]);