shithub: libvpx

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vp8e - static key boost

This seeks to boost the size of the keyframe if the entire section
is a single frame clip

Change-Id: I3c00268dc155b047dc4b90e514cf403d55a4f8ef

--- a/vp8/encoder/firstpass.c

+++ b/vp8/encoder/firstpass.c

@@ -2953,10 +2953,26 @@

         // We do three calculations for kf size.

         // The first is based on the error score for the whole kf group.

-        // The second (optionaly) on the key frames own error if this is smaller than the average for the group.

-        // The final one insures that the frame receives at least the allocation it would have received based on its own error score vs the error score remaining

-

-        allocation_chunks = ((cpi->twopass.frames_to_key - 1) * 100) + kf_boost;           // cpi->twopass.frames_to_key-1 because key frame itself is taken care of by kf_boost

+        // The second (optionaly) on the key frames own error if this is

+        // smaller than the average for the group.

+        // The final one insures that the frame receives at least the

+        // allocation it would have received based on its own error score vs

+        // the error score remaining

+        // Special case if the sequence appears almost totaly static

+        // as measured by the decay accumulator. In this case we want to

+        // spend almost all of the bits on the key frame.

+        // cpi->twopass.frames_to_key-1 because key frame itself is taken

+        // care of by kf_boost.

+        if ( decay_accumulator >= 0.99 )

+        {

+            allocation_chunks =

+                ((cpi->twopass.frames_to_key - 1) * 10) + kf_boost;

+        }

+        else

+        {

+            allocation_chunks =

+                ((cpi->twopass.frames_to_key - 1) * 100) + kf_boost;

+        }

         // Normalize Altboost and allocations chunck down to prevent overflow

         while (kf_boost > 1000)

-- 

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