This commit compares the current original frame to the previous
original frame at 64x64 block level and decides if the entire
block belongs to background area. If it is in the background area,
skip non-RD partition search and copy the partition types of the
collocated block in the previous frame.

For vidyo1 in the rtc set, this makes the speed -5 coding speed
about 8% faster. The overall compression performance is down by
1.37% for rtc set.

Change-Id: Iccf920562fcc88f21d377fb6a44c547c8689b7ea

This commit changed the initialization of best_mode_index to -1 to make
sure it is not mistakenly used for mode masking.

Change-Id: I75b05db51466070dd23c4ee57a4d4b40764dc019

Change-Id: I08aa0c213df34c084eb7a3c51b6b3306e49c7757

This reverts commit 22a3e307

Change-Id: I460d905edf5fb2006da58c18fbe02c04d0c631bb

Change-Id: I0462bf1ca1b4e5a1c06259979b4daff949b8a2c6

Change-Id: I1324c339815a47004ddccdaf651d24c60382b92f

Change-Id: Ie26b6ca8de733a527f820b16148e7a2231073f0f

Cleanup.

Change-Id: I54d989e24b35323cda7290654e425565d5c9ea2d

Change-Id: I721ff26e3d5dbef80b8cd2dd562adae3748f6687

Change-Id: I9be2e4e9aeda0fae6dc946deae2999be51daebe0

In mode selection loop, once mode_index pass mode_skip_start, all
modes with a different reference frame from current best mode are
masked out using mode_skip_mask.

However, the setting of mode_skip_mask may use an invalid mode if
there is no mode tested yet. This commit fixes the issue by making
sure a mode has been tested and selected. Otherwise, no mode will be
masked out because of their reference frame.

Change-Id: Ib0009e8a96836a65cf5347440fff8a2e1a67f29f

Change-Id: I9b8f9a3f4fa9d48695149dd68ecb5e8d84accafe

Change-Id: Idf612c772440158cd1645623241c51ab0d57405c

This patch fixed the uninitialized read errors in Issue 748:
"dr memory VP9 encode errors". In vp9_convolve_avg_sse2,
when width is 4, pavgb reads 8 bytes from dst buffer that is
out of range. An error is reported although the data is not
actually used later. This issue was resolved by preventing
uninitialized reads.

Change-Id: I109a54910aa47139cb13119de86f2062cff207df

Change-Id: I7a5230852cb24ce22bfe85ea2608cdb4619b5200

Change-Id: I08fe184a04e5435aeac92f1d7cc9733ca52c2783

Change-Id: Ib64edeb58b3e25488fb85bbe85c9decb15b4d0a1