Commit ede0b15c authored by Fritz Koenig's avatar Fritz Koenig
Browse files

Reduce motion vector search on alt-ref frame.

Clamp mv search to accomodate subpixel filtering
of UV mv.

Change-Id: Iab3ed405993ef6bf779ad7cf60863153068fb7d1
parent 973a9c07
......@@ -259,10 +259,19 @@ static void vp8_temporal_filter_iterate_c
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++)
......@@ -274,10 +283,9 @@ static void vp8_temporal_filter_iterate_c
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++)
......
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