This patch revamps the entropy coding of coefficients to code first
a non-zero count per coded block and correspondingly remove the EOB
token from the token set.

STATUS:
Main encode/decode code achieving encode/decode sync - done.
Forward and backward probability updates to the nzcs - done.
Rd costing updates for nzcs - done.
Note: The dynamic progrmaming apporach used in trellis quantization
is not exactly compatible with nzcs. A suboptimal approach has been
used instead where branch costs are updated to account for changes
in the nzcs.

TODO:
Training the default probs/counts for nzcs

Change-Id: I951bc1e22f47885077a7453a09b0493daa77883d

Split macroblock and superblock tokenization and detokenization
functions and coefficient-related data structs so that the bitstream
layout and related code of superblock coefficients looks less like it's
a hack to fit macroblocks in superblocks.

In addition, unify chroma transform size selection from luma transform
size (i.e. always use the same size, as long as it fits the predictor);
in practice, this means 32x32 and 64x64 superblocks using the 16x16 luma
transform will now use the 16x16 (instead of the 8x8) chroma transform,
and 64x64 superblocks using the 32x32 luma transform will now use the
32x32 (instead of the 16x16) chroma transform.

Lastly, add a trellis optimize function for 32x32 transform blocks.

HD gains about 0.3%, STDHD about 0.15% and derf about 0.1%. There's
a few negative points here and there that I might want to analyze
a little closer.

Change-Id: Ibad7c3ddfe1acfc52771dfc27c03e9783e054430

Change-Id: I5416455f8f129ca0f450d00e48358d2012605072

This patch alters the balance of context between the
coefficient bands (reflecting the position of coefficients
within a transform blocks) and the energy of the previous
token (or tokens) within a block.

In this case the number of coefficient bands is reduced
but more previous token energy bands are supported.

Some initial rebalancing of the default tables has been
by running multiple derf clips at multiple data rates using
the ENTOPY_STATS macro. Further balancing needs to be
done using larger image formatsd especially in regard to
the bigger transform sizes which are not as well represented
in encodings of smaller image formats.

Change-Id: If9736e95c391e711b04aef6393d26f60f36e1f8a

Change-Id: I7a5314daca993d46b8666ba1ec2ff3766c1e5042

allowing the compiler to inline.

Change-Id: I66e5caf5e7fefa68a223ff0603aa3f9e11e35dbb

This patch abstracts the selection of the coefficient band
context into a function as a precursor to further experiments
with the coefficient context.

It also removes the large per TX size coefficient band structures
and uses a single matrix for all block sizes within the test function.

This may have an impact on quality (results to follow) but is only an
intermediate step in the process of redefining the context. Also the
quality impact will be larger initially because the default tables will
be out of step with the new banding.

In particular the 4x4 will in this case only use 7 bands. If needed we
can add back block size dependency localized within the function, but
this can follow on after the other changes to the definition of the
context.

Change-Id: Id7009c2f4f9bb1d02b861af85fd8223d4285bde5

This is an initial step to facilitate experimentation
with changes to the prior token context used to code
coefficients to take better account of the energy of
preceding tokens.

This patch merely abstracts the selection of context into
two functions and does not alter the output.

Change-Id: I117fff0b49c61da83aed641e36620442f86def86

Removal of the  NEWCOEFCONTEXT experiment to
reduce code clutter and make it easier to experiment with
some other changes to the coefficient coding context.

Change-Id: Icd17b421384c354df6117cc714747647c5eb7e98

Change-Id: I615651e4c7b09e576a341ad425cf80c393637833

Change-Id: I0df99742029834a85c4933652b0587cf5b6b2587

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

For coefficients, use int16_t (instead of short); for pixel values in
16-bit intermediates, use uint16_t (instead of unsigned short); for all
others, use uint8_t (instead of unsigned char).

Change-Id: I3619cd9abf106c3742eccc2e2f5e89a62774f7da

This matches the names of tables for all other transform sizes.

Change-Id: Ia7681b7f8d34c97c27b0eb0e34d490cd0f8d02c6

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

Use these, instead of the 4/5-dimensional arrays, to hold statistics,
counts, accumulations and probabilities for coefficient tokens. This
commit also re-allows ENTROPY_STATS to compile.

Change-Id: If441ffac936f52a3af91d8f2922ea8a0ceabdaa5

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

Change-Id: I2c252f3ddcc99e96c1f5d3dab8bcb25a2a3637ea

Change-Id: Ia1cce221f8511561b9cbd8edb7726fbc286ff243

Support for gyp which doesn't support multiple objects in the same
static library having the same basename.

Change-Id: Ib947eefbaf68f8b177a796d23f875ccdfa6bc9dc

Experiments with a larger set of contexts and some
clean up to replace magic numbers regarding the
number of contexts.

The starting values and rate of backwards adaption
are still suspect and based on a small set of tests.
Added forwards adjustment of probabilities.

The net result of adding the new context and forward
update is small compared to the old context from the
legacy find_near function.  (down a little on derf but
up by a similar amount for HD)

HOWEVER.... with the new context and forward update
the impact of disabling the reverse update (which may be
necessary in some use cases to facilitate parallel decoding)
is hugely reduced.

For the old context without forward update, the impact of
turning off reverse update (Experiment was with SB off) was
Derf - 0.9, Yt -1.89, ythd -2.75 and sthd -8.35. The impact was
mainly at low data rates.

With the new context and forward update enabled the impact
for all the test sets was no more than 0.5-1% (again most at
the low end).

Change-Id: Ic751b414c8ce7f7f3ebc6f19a741d774d2b4b556

Change-Id: Ic084c475844b24092a433ab88138cf58af3abbe4

For non-static functions, change the prefix to vp9_. For static functions,
remove the prefix. Also fix some comments, remove unused code or unused
function prototypes.

Change-Id: I1f8be05362f66060fe421c3d4c9a906fdf835de5

This change encompasses VP8_PTR, VP8_COMP, VP8D_COMP, VP8_COMMON,
VP8Decompressor and VP8Common.

Change-Id: I514ef4ad4e682370f36d656af1c09ee20da216ad

For local symbols, make them static instead.

Change-Id: I13d60947a46f711bc8991e16100cea2a13e3a22e

Change-Id: Ic5a5f60e1ff9d9ccae4174160d36529466eeb509

Change-Id: I99f1982b30a630a9a070a8326d83b34a33cba14c

Packs the bitstream with each mb's residual following its mode/mv
information.

TODO: There are still a few fields that should be packed into partition
0 but are included in partition 1, due to them being serialized from
write_kfmodes/pack_inter_mode_mvs, which execute after the first
partition is finalized. These need to be separated out into a separate
function, similar to mb_mode_mv_init() in decodemv.c.

Change-Id: I43a46c363601ab36954d07ebe498760e1e2e3af4

Change-Id: I22aa803ffff330622cdb77277e7b196a9766f882

Separates the entropy coding context models for 4x4, 8x8 and 16x16
ADST variants.

There is a small improvement for HD (hd/std-hd) by about 0.1-0.2%.
Results on derf/yt are about the same, probably because there is not
enough statistics.

Results may improve somewhat once the initial probability tables are
updated for the hybrid transforms which is coming soon.

Change-Id: Ic7c0c62dacc68ef551054fdb575be8b8507d32a8

With this change, even if hybridtransform8x8 experiment is off,
8x8 dct is used for the I8x8 mode. However note that the gains
observed with the hybridtransform8x8 experiment will now be less,
since part of the gain is now merged in.

Change-Id: I9afb3880906fd0a1368a374041fc08efcf060c54

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

Merged in the high_precision_mv experiment to make it easier
to work on new mv encoding strategies. Also removed
coef_update_probs3().

Change-Id: I82d3b0bb642419fe05dba82528bc9ba010e90924

Fixed the code review comments.

Under the htrans8x8 experiment the 8X8 DCT in the
I8X8 mode is replaced with a combination of 8X8 ADST and
DCT.

Overall coding gains with the htrans8x8 experiment are:
derf:   0.486
std-hd: 1.040
hd:     1.063
yt:     0.506

Note that part of the gain comes from bigger transforms
(8x8 instead of 4x4) and part comes from replacing the DCT
wth the ADST.

Change-Id: I92ca6bbfce11b4165d612b81d9adfad4d010c775

Set on all 16x16 intra/inter modes

Features:
- Butterfly fDCT/iDCT
- Loop filter does not filter internal edges with 16x16
- Optimize coefficient function
- Update coefficient probability function
- RD
- Entropy stats
- 16x16 is a config option

Have not tested with experiments.

hd:     2.60%
std-hd: 2.43%
yt:     1.32%
derf:   0.60%

Change-Id: I96fb090517c30c5da84bad4fae602c3ec0c58b1c

Apply 2D-DCT transform of dimension 8x8 to encode prediction
residuals of I8X8 mode.
Brought back block type 3 probability context model for 8x8 tokens,
which is used for the coefficients of Y blocks in I8x8 modes. The
coefficient costs estimate of I8X8 mode in rate-distortion is also
changed appropriately.
Performance results:
derf:   0.246
yt:     0.114
std-hd: 0.730
hd:     0.670

Change-Id: If1d970eeb4e1827c9f0d2c5b27d33089b347ea27

Allows for swtiching/setting interpolation filters at the MB
level. A frame level flag indicates whether to use a specifc
filter for the entire frame or to signal the interpolation
filter for each MB. When switchable filters are used, the
encoder chooses between 8-tap and 8-tap sharp filters. The
code currently has options to explore other variations as well,
which will be cleaned up subsequently.

One issue with the framework is that encoding is slow. I
tried to do some tricks to speed things up but it is still slow.
Decoding speed should not be affected since the number of
filter taps remain unchanged.

With the current version, we are up 0.5% on derf on average but
some videos city/mobile improve by close to 4 and 2% respectively.
If we did a full-search by turning the SEARCH_BEST_FILTER flag
on, the results are somewhat better.

The framework can be combined with filtered prediction, and I
seek feedback regarding that.

Rebased.

Change-Id: I8f632cb2c111e76284140a2bd480945d6d42b77a

The following five experiments are merged:

newentropy
newupdate
adaptive_entropy (also includes a couple of parameter changes
                  that improves results a little
                  in common/entropymode.c and encoder/modecosts.c
                  that were not merged from the internal branch)
newintramodes
expanded_coef_context

Change-Id: I8a142a831786ee9dc936f22be1d42a8bced7d270

Adds ADST/DCT hybrid transform coding for Intra4x4 mode.
The ADST is applied to directions in which the boundary
pixels are used for prediction, while DCT applied to
directions without corresponding boundary prediction.

Adds enum TX_TYPE in b_mode_infor to indicate the transform
type used.

Make coding style consistent with google style.
Fixed the commented issues.

Experimental results in terms of bit-rate reduction:
derf:   0.731%
yt:     0.982%
std-hd: 0.459%
hd:     0.725%

Will be looking at 8x8 transforms next.

Change-Id: I46dbd7b80dbb3e8856e9c34fbc58cb3764a12fcf

Approximate the Google style guide[1] so that that there's a written
document to follow and tools to check compliance[2].

[1]: http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml
[2]: http://google-styleguide.googlecode.com/svn/trunk/cpplint/cpplint.py

Change-Id: Idf40e3d8dddcc72150f6af127b13e5dab838685f