ref: 84c3cd79d1f551f18fb74db7405f5df1f3260129
parent: 7f0b11c0ae8d90144bb44118350dd1cd0498c0ee
parent: ede0b15c9d0d05f0d53a13e5962192f9d29edc13
author: Fritz Koenig <frkoenig@google.com>
date: Wed Jul 13 06:07:30 EDT 2011
Merge "Reduce motion vector search on alt-ref frame."
--- a/vp8/encoder/temporal_filter.c
+++ b/vp8/encoder/temporal_filter.c
@@ -262,10 +262,19 @@
for (mb_row = 0; mb_row < mb_rows; mb_row++)
{#if ALT_REF_MC_ENABLED
- // Reduced search extent by 3 for 6-tap filter & smaller UMV border
- cpi->mb.mv_row_min = -((mb_row * 16) + (VP8BORDERINPIXELS - 19));
+ // Source frames are extended to 16 pixels. This is different than
+ // L/A/G reference frames that have a border of 32 (VP8BORDERINPIXELS)
+ // A 6 tap filter is used for motion search. This requires 2 pixels
+ // before and 3 pixels after. So the largest Y mv on a border would
+ // then be 16 - 3. The UV blocks are half the size of the Y and
+ // therefore only extended by 8. The largest mv that a UV block
+ // can support is 8 - 3. A UV mv is half of a Y mv.
+ // (16 - 3) >> 1 == 6 which is greater than 8 - 3.
+ // To keep the mv in play for both Y and UV planes the max that it
+ // can be on a border is therefore 16 - 5.
+ cpi->mb.mv_row_min = -((mb_row * 16) + (16 - 5));
cpi->mb.mv_row_max = ((cpi->common.mb_rows - 1 - mb_row) * 16)
- + (VP8BORDERINPIXELS - 19);
+ + (16 - 5);
#endif
for (mb_col = 0; mb_col < mb_cols; mb_col++)
@@ -277,10 +286,9 @@
vpx_memset(count, 0, 384*sizeof(unsigned short));
#if ALT_REF_MC_ENABLED
- // Reduced search extent by 3 for 6-tap filter & smaller UMV border
- cpi->mb.mv_col_min = -((mb_col * 16) + (VP8BORDERINPIXELS - 19));
+ cpi->mb.mv_col_min = -((mb_col * 16) + (16 - 5));
cpi->mb.mv_col_max = ((cpi->common.mb_cols - 1 - mb_col) * 16)
- + (VP8BORDERINPIXELS - 19);
+ + (16 - 5);
#endif
for (frame = 0; frame < frame_count; frame++)