Added a new expt rect-tx to be used in conjunction with ext-tx.
[rect-tx is a temporary config flag and will eventually be
merged into ext-tx once it works correctly with all other
experiments].
Added 4x8 and 8x4 tranforms for use initially with rectangular
sub8x8 y blocks as part of this experiment.
There is about a -0.2% BDRATE improvement on lowres, others pending.
When var-tx is on rectangular transforms are currently not used.
That will be enabled in a subsequent patch.
Change-Id: Iaf3f88ede2740ffe6a0ffb1ef5fc01a16cd0283a
Removes integer divides from backward updates for VP10.
Currently this is put in as part of the entropy experiment.
Coding efficiency change is in the noise level.
Change-Id: I5b3c0ab6169ee6d82d0ca1778e264fd4577cdd32
This will facilitate bringing the zero node into the token set while
allowing its probability to vary independently.
Change-Id: I57b44c0fce44debb8e612021e44713b229d1b3cf
This patch added two features to improve entropy coding efficiency
for coefficient tokens.
1. Choose 1 of 4 default probability tables based on q-index for
key-frames.
It is ported from nextgen branch:
https://chromium-review.googlesource.com/#/c/280586/
2. Do backward update after each superblock (64X64) row using
subframe token counts.
Coding gain: 0.1% on lowres; 0.42% on midres; 0.36% on hdres.
Much larger gain for key-frames: 2.6%, 2.3%, 1.7%.
Design doc: go/huisu-entropy
Change-Id: Ia3b6a615636be09247d70e4c520405637561532b
Make the RANS implementation operate on cumulative distribution
functions rather than individual probability distribution functions.
CDFs have shown themselves more flexible to work with.
Reduces decoding memory usage from scaling O(num_distributions *
symbol_resolution) to O(num_distributions).
No bitstream change. This is an purely implementation change.
Change-Id: I4e18d3a0a3d37a36a61487c3d778f9d088b0b374
Don't initialize first pass costs for a number of symbols where first
pass probabilities aren't initialized.
As a side effect, an illegal read in the ANS experiment is fixed.
https://bugs.chromium.org/p/webm/issues/detail?id=1089
Change-Id: I97438c357bd88f52f5a15c697031cf0c3cc8f510
The old workaround "p = 0 ? 0 : p -1" is misleading.
?: happens before =
assigning back to p truncates to one byte.
Therefore it is equivalent to (p - 1) & 0xFF, but the check just exists
to work around a first pass bug, so let's make the work around more
clear.
https://bugs.chromium.org/p/webm/issues/detail?id=1089
Change-Id: I587c44dd61c1f3767543c0126376f881889935af
This reverts commit 7f56cb29787b187c8cb1b778918ca3b80184c804.
It causes uninitialized reads in the first pass setting up later cost tables.
Change-Id: I2df498df3f5c03eff359f79edf045aed0c618dc9
The old workaround "p = 0 ? 0 : p -1" is misleading.
?: happens before =
assigning back to p truncates to one byte.
Therefore it is equivalent to (p - 1) & 0xFF, but the check just exists
to work around a first pass bug, so let's make the work around more
clear.
https://code.google.com/p/webm/issues/detail?id=1089
Change-Id: Ia6dcc8922e1acbac0eeca23a4d564a355c489572
