This causes the output of find_ref_mvs() to always be unique or zero.
A nice side-effect of this is that it also causes the output of
find_ref_mvs_sub8x8() to be unique-or-zero, and it will not ignore
available candidate MVs under certain conditions.
See issue 1012.
Change-Id: If4792789cb7885dbc9db420001d95f9b91b63bfa
In VP9, the ref MV had to point to a block that itself fully resided
within the visible image, i.e. all borders of the image had to be
within the visible borders of the coded frame. This is somewhat
illogical, and had obscure side effects, e.g. clamping of fairly
reasonable motion vectors such as 0,0 were clipped to negative values
if the block was overhanging on frame edges (such as the last rows
on 1080p content), which makes no sense whatsoever.
Instead, relax clamping constraints such that the ref MVs are allowed
to point to blocks exactly outside the visible edges in both Y as well
as UV planes, including the 8tap filter edges (that's why the offset is
8 pixels + block size).
See issue 1037.
Change-Id: I2683eb2a18b24955e4dcce36c2940aa2ba3a1061
This actually has no effect whatsoever, since the input MVs themselves
are clamped by clamp_mv_ref() already, which is significantly more
restrictive in its bounds.
Change-Id: I4a3a7b2b121ee422c56428c2a12d930c3813c06e
This has virtually no effect on coding efficiency, but it is more
logical from a theoretical perspective (since it makes no sense to
me that you would exclude a MV from a list just because it's sign-
inversed value is identical to a value already in a list), and it
also makes the code simpler (it removes a duplicate value check in
cases where signbias is equal between the two MVs being compared).
See issue 662.
Change-Id: I23e607c6de150b9f11d1372fb2868b813c322d37
