Changes to allow high bit depth and palette to be enabled at the
same time by using a 16 bit (instead of 8bit) palette when high
bit depth is enabled and modifying related functions accordingly.
Change-Id: I97d30b4d9338d3a51db02c94bc568eba60a8905d
The basic idea is to use a pixel’s neighboring colors as
context to predict its own color. Up to 4 neighbors are
considered here: left, left-above, above, right-above.
To reduce the number of contexts, the combination of any
4 (or less) colors are mapped to a reduced number of
patterns. For example, 1111, 2222, 3333, … , can be mapped
to the same pattern: AAAA. SImilarly, 1122, 1133, 2233, …,
can be mapped to the pattern AABB. In this way, the total
number of color contexts is reduced to 16.
This almost doubles the gain of palette coding on screen
content videos.
on screen_content
--enable-palette +14.2%
--enable-palette --enable-tx-skip +21.2%
on derflr
--enable-palette +0.12%
with all other experiments +6.16%
Change-Id: I560306dae216f2ac11a9214968c2ad2319fa1718
Also make changes to transmit palette-enabled flag using
neighbor blocks as context.
on screen_content
--enable-palette +7.35%
on derflr
with all other experiments +6.05%
Change-Id: Id6c2f726d21913d54a3f86ecfea474a4044c27f6
on screen_content
--enable-palette +6.74%
on derflr
with all other experiments +6.02%
(--enable-supertx --enable-copy-mode
--enable-ext-tx --enable-filterintra
--enable-tx64x64 --enable-tx-skip
--enable-interintra --enable-wedge-partition
--enable-compound-modes --enable-new-quant
--enable-palette)
Change-Id: Ib85049b4c3fcf52bf95efbc9d6aecf53d53ca1a3
Added palette coding option for Y channel only, key frame only.
Palette colors are obtained with k-means clustering algorithm.
Run-length coding is used to compress the color indices.
On screen_content:
--enable-palette + 5.75%
--enable-palette --enable-tx_skip +15.04% (was 13.3%)
On derflr:
--enable-palette - 0.03%
with all the other expriments + 5.95% (was 5.98%)
Change-Id: I6d1cf45c889be764d14083170fdf14a424bd31b5
