Extend experiment to use both vectors from MBs
coded using compound prediction as candidates.
In final sort only consider best 4 candidates
for now but make sure 0,0 is always one of them.
Other minor changes to new MV reference code.
Pass in Mv list to vp8_find_best_ref_mvs().
Change-Id: Ib96220c33c6b80bd1d5e0fbe8b68121be7997095
Alternative strategy for finding a list of candidate motion
vectors to use as reference values in mv coding and as
nearest and near.
Sort by sad in vp8_find_best_ref_mvs() rather than just
pick the best. Allow 0,0 as a best ref option but not a
nearest or near unless there are no alternatives.
Encode/Decode verified on at least some clips.
Some commented out experimental and stats code still in place.
Gain over existing code averages about 1% on derf (alll metrics)
with improvement on all clips. Other test results pending.
The entropy coding of the mode (nearest/near etc) still
depends upon and requires the old "findnear" code so
this needs looking at and may provide room for further gains.
Change-Id: I871d7cba1d1c379c4bad9bcccce1fb19c46b8247
