tree adede74db223308a99f611258bf01a18443f3e32
parent 4c09b4542f0e23bcac76cfb8200132783195911e
author Elliott Karpilovsky <elliottk@google.com> 1572566810 -0700
committer Elliott Karpilovsky <elliottk@google.com> 1572628823 +0000

Only write mode-ref-delta if meaningful

Instead of writing 0 values when all mode-ref-deltas are zero,
signal at a higher level that no deltas will be present.

STATS_CHANGED

Improves PSNR BDrate by ~0.01% (midres) to ~0.02% (lowres). No speed change.

Change-Id: Ib1b8fc011873504ba6982af9a37f4df00f0114e9