tree 7a9c54ccb7fc422e1a802a8bdc01031e67e133e0
parent fc6bcc754acf5be4c1615d4b90ad4a577897c8e2
author Urvang Joshi <urvang@google.com> 1548719130 -0800
committer Urvang Joshi <urvang@google.com> 1549319256 +0000

max_ref_frames enforcement at beginning of frame.

Earlier, this was done by setting 'mask->ref_frame1' and
'mask->ref_frame2' for disabling a given reference frame, at each block.

But this wasn't enough, as compound references could still use that
frame as one of the two references (if the other reference was enabled),
because of the 'AND' logic in mask_says_skip() function.

The correct way to enforce max frames is to instead disable these
reference frames through cpi->ref_frame_flags directly at the beginning
of a frame.

With this correction, all values of 'max_reference_frames' from 3 to 7
are now supported.

Change-Id: Ie15c2d1ab702d82de4cc10642596c20d9cd13f65