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Refactor the 8x8 inverse hybrid transform. It is now consistent
with the new inverse DCT. Overall performance loss (due to the
use of this variant ADST, and the rounding errors in the butterfly
implementation) for std-hd is -0.02.

Fixed BUILD warning.

Devise a variant of the original ADST, which allows butterfly
computation structure. This new transform has kernel of the
form: sin((2k+1)*(2n+1) / (4N)). One of its butterfly structures
using floating-point multiplications was reported in Z. Wang,
"Fast algorithms for the discrete W transform and for the discrete
Fourier transform", IEEE Trans. on ASSP, 1984.

This patch includes the butterfly implementation of the inverse
ADST/DCT hybrid transform of dimension 8x8.

Change-Id: I3533cb715f749343a80b9087ce34b3e776d1581d

Change-Id: I8508f1a3d3430f998bb9295f849e88e626a52a24

This experiment gives little gains and adds relatively much code
complexity (and it hinders other experiments), so let's get rid of
it.

Change-Id: Id25e79a137a1b8a01138aa27a1fa0ba4a2df274a

Change-Id: Iac7f3d108863552b850c92c727e00c95571c9e96

Change-Id: I0c94475075e66e13cfe4c20fab7db6474441ae86

Change-Id: Ibcc342efac0a9be7a21d9b2c09984d9e16bbb225

Removed the experimental flag from around the prediction filter.

Change-Id: Ic1dd2db8fe8ac17ed5129f83094d4c5cdd5527d2

Change-Id: I615651e4c7b09e576a341ad425cf80c393637833

Change-Id: If6c88752dffdb566f8d4322f135145270716fb8e

when larger transforms are used

Change-Id: I25251442b44bf251df4c25a1c1fcf71fb2ad913b

This patch removes the old pred-filter experiment and replaces it
with one that is implemented using the switchable filter framework.

If the pred-filter experiment is enabled, three interopolation
filters are tested during mode selection; the standard 8-tap
interpolation filter, a sharp 8-tap filter and a (new) 8-tap
smoothing filter.

The 6-tap filter code has been preserved for now and if the
enable-6tap experiment is enabled (in addition to the pred-filter
experiment) the original 6-tap filter replaces the new 8-tap smooth
filter in the switchable mode.

The new experiment applies the prediction filter in cases of a
fractional-pel motion vector. Future patches will apply the filter
where the mv is pel-aligned and also to intra predicted blocks.

Change-Id: I08e8cba978f2bbf3019f8413f376b8e2cd85eba4

This is to add to the 64x64 transform experiment as an alternative to
a 64x64 DCT.
Two levels of wavelet decomposition is used on a 64x64 block, followed
by 16x16 DCT on the four lowest subbands. The highest three subbands
are left untransformed after the first level DWT.

Change-Id: I3d48d5800468d655191933894df6b46e15adca56

3.2% gains on std/hd, 1.0% gains on hd.

Change-Id: I481d5df23d8a4fc650a5bcba956554490b2bd200

Adds an experiment to derive the previous context of a coefficient
not just from the previous coefficient in the scan order but from a
combination of several neighboring coefficients previously encountered
in scan order.  A precomputed table of neighbors for each location
for each scan type and block size is used. Currently 5 neighbors are
used.

Results are about 0.2% positive using a strategy where the max coef
magnitude from the 5 neigbors is used to derive the context.

Change-Id: Ie708b54d8e1898af742846ce2d1e2b0d89fd4ad5

Change-Id: I63423f8f2ec152cb490ddd9e6a94e431a11858f6

First attempt at avoiding all the compile-time environment detection for
cases where you can generate the environments statically, as when the
real build is being performed by another build system.

Change-Id: Ie3cf95d71d6c5169900f31e263b84bc123cdf73f

This commit changed the ENTROPY_CONTEXT conversion between MBs that
have different transform sizes.

In additioin, this commit also did a number of cleanup/bug fix:
1. removed duplicate function vp9_fix_contexts() and changed to use
vp8_reset_mb_token_contexts() for both encoder and decoder
2. fixed a bug in stuff_mb_16x16 where wrong context was used for
the UV.
3. changed reset all context to 0 if a MB is skipped to simplify the
logic.

Change-Id: I7bc57a5fb6dbf1f85eac1543daaeb3a61633275c

This adds Debargha's DCT/DWT hybrid and a regular 32x32 DCT, and adds
code all over the place to wrap that in the bitstream/encoder/decoder/RD.

Some implementation notes (these probably need careful review):
- token range is extended by 1 bit, since the value range out of this
  transform is [-16384,16383].
- the coefficients coming out of the FDCT are manually scaled back by
  1 bit, or else they won't fit in int16_t (they are 17 bits). Because
  of this, the RD error scoring does not right-shift the MSE score by
  two (unlike for 4x4/8x8/16x16).
- to compensate for this loss in precision, the quantizer is halved
  also. This is currently a little hacky.
- FDCT and IDCT is double-only right now. Needs a fixed-point impl.
- There are no default probabilities for the 32x32 transform yet; I'm
  simply using the 16x16 luma ones. A future commit will add newly
  generated probabilities for all transforms.
- No ADST version. I don't think we'll add one for this level; if an
  ADST is desired, transform-size selection can scale back to 16x16
  or lower, and use an ADST at that level.

Additional notes specific to Debargha's DWT/DCT hybrid:
- coefficient scale is different for the top/left 16x16 (DCT-over-DWT)
  block than for the rest (DWT pixel differences) of the block. Therefore,
  RD error scoring isn't easily scalable between coefficient and pixel
  domain. Thus, unfortunately, we need to compute the RD distortion in
  the pixel domain until we figure out how to scale these appropriately.

Change-Id: I00386f20f35d7fabb19aba94c8162f8aee64ef2b

A patch on compound inter-intra prediction.

In compound inter-intra prediction, a new predictor for
16x16 inter coded MBs are obtained by combining a single
inter predictor with a 16x16 intra predictor, in a manner
that the weight varies with distance from the top/left
boundary. The current search strategy is to combine the best
inter mode with the best intra mode obtained independently.

Results so far:

derf +0.31%
yt +0.32%
std-hd +0.35%
hd +0.42%

It is conceivable that the results would improve somewhat
with a more thorough search strategy where all intra modes
are searched given the best mv, or even a joint search for
the best mv and the best intra mode.

Change-Id: I7951f1ed0d6eb31ca32ac24d120f1585bcd8d79b

Preliminary patch on a new 4x4 intra mode B_CONTEXT_PRED where the
dominant direction from the context is used to encode. Various decoder
changes are needed to support decoding of B_CONTEXT_PRED in conjunction
with hybrid transforms since the scan order and tokenization depends on
the actual direction of prediction obtained from the context. Currently
the traditional directional modes are used in conjunction with the
B_CONTEXT_PRED, which also seems to provide the best results.

The gains are small - in the 0.1% range.

Change-Id: I5a7ea80b5218f42a9c0dfb42d3f79a68c7f0cdc2

Change-Id: Ib39ad47a7d188f3b45416937b7eeb28c3e79b74c

Documentation is typically auto-detected by checking for php and
doxygen. Add an option to explicitly disable it.

Remove toggle keywords from libraries, examples, documentation and
unit tests. They were not consistent with the default status.

Change-Id: I21049675ccfd8e58ac612cd058641b197db5c0eb

Change-Id: Ic084c475844b24092a433ab88138cf58af3abbe4

Delete code relating to featureupdates experiment.

Change-Id: If218762c658bb8cbb3007cf2069123b3e05adcbc

As suggested by Paul, this commit separate the subpel refmv selection
into a separate experiment. It also changed a couple variable names
to better reflect the nature of the variables.

Change-Id: Id951c3cadc61a982dd15afe641000f60213b8995

Now this experiment has been merged.

Change-Id: I6c93784df89434c52a4eb8f977cd3745e269abf9

This way, the code is not compiled in by default, thus decreasing
overall binary size.

Change-Id: I85cac8f5a22a51a7d99c820ef6d6ed179d4106a0

Change-Id: I0d306b0062be59bc785b65882691c956c8b5e7c8

Removes the old mv encoding code.

Change-Id: I1026d48cc5ac15ccb776f98463e929254c3dc7da

Change-Id: I99f1982b30a630a9a070a8326d83b34a33cba14c

Change-Id: I22aa803ffff330622cdb77277e7b196a9766f882

Documentation is typically auto-detected by checking for php and
doxygen. Add an option to explicitly disable it.

Remove toggle keywords from libraries, examples, documentation and
unit tests. They were not consistent with the default status.

Change-Id: I21049675ccfd8e58ac612cd058641b197db5c0eb

Results: derf (vanilla or +hybridtx) +0.2% and (+hybrid16x16
or +tx16x16) +0.7%-0.8%; HD (vanilla or +hybridtx) +0.1-0.2%
and (+hybrid16x16 or +tx16x16) +1.4%, STD/HD (vanilla or +hybridtx)
about even, and (+hybrid16x16 or +tx16x16) +0.8-1.0%.

Change-Id: I03899e2f7a64e725a863f32e55366035ba77aa62

Adds a new experiment with redesigned/refactored motion vector entropy
coding. The patch also takes a first step towards separating the
integer and fractional pel components of a MV. However the fractional
pel encoding still depends on the integer pel part and so they are
not fully independent. Further experiments are in progress to see
how much they can be decoupled without affecting performance.
All components including entropy coding/decoding, costing for MV
search, forward updates and backward updates to probability tables,
have been implemented.

Results so far:
derf: +0.19%
std-hd: +0.28%
yt: +0.80%
hd: +1.15%

Patch: Simplifies the fractional pel models:
derf: +0.284%
std-hd: +0.289%
yt: +0.849%
hd: +1.254%

Patch: Some changes in the models, rebased.
derf: +0.330%
std-hd: +0.306%
yt: +0.816%
hd: +1.225%

Change-Id: I646b3c48f3587f4cc909639b78c3798da6402678

Enable ADST/DCT of dimension 16x16 for I16X16 modes. This change provides
benefits mostly for hd sequences.

Set up the framework for selectable transform dimension.

Also allowing quantization parameter threshold to control the use
of hybrid transform (This is currently disabled by setting threshold
always above the quantization parameter. Adaptive thresholding can
be built upon this, which will further improve the coding performance.)

The coding performance gains (with respect to the codec that has all
other configuration settings turned on) are

derf:   0.013
yt:     0.086
hd:     0.198
std-hd: 0.501

Change-Id: Ibb4263a61fc74e0b3c345f54d73e8c73552bf926

Alternative strategy for finding a list of candidate motion
vectors to use as reference values in mv coding and as
nearest and near.

Sort by sad in vp8_find_best_ref_mvs() rather than just
pick the best. Allow 0,0 as a best ref option but not a
nearest or near unless there are no alternatives.

Encode/Decode verified on at least some clips.

Some commented out experimental and stats code still in place.

Gain over existing code averages about 1% on derf (alll metrics)
with improvement on all clips. Other test results pending.

The entropy coding of the mode (nearest/near etc) still
depends upon and requires the old "findnear" code so
this needs looking at and may provide room for further gains.

Change-Id: I871d7cba1d1c379c4bad9bcccce1fb19c46b8247

This is being reimplemented more generically in terms of affine
transforms.

Change-Id: I9300bfde5f8b93c708c64f59427087720f8ed782

Change-Id: I4b911e4173da30c164bde7ea50bc80a70fbbb745

If you build with --enabled-shared on a Linux arch not explicitly
listed, the configure script will abort because it didn't detect
"linux" in the fallback generic-gnu tuple.

Since this is the fallback tuple and people are passing
--enable-shared, assume the user knows what they're in for.

Change-Id: Ia35b657e7247c8855e3a94fca424c9884d4241e3

Also add warnings for undefined macros in the C pre-processor

Change-Id: I1ec30e57c5a49fb72151a4cf140d7eeb0fb1d779