Change-Id: I6bbed8bcb2dfa3458ffc59179dfba66c92e18125

Previously, the mode context is always udpated based on stats of current
frame, when there is no count, 50% is used for both left and right branch.
However, it is observed that with such strategy, a small count or no count
at all can skew the probability distribution significantly. This commmit
changed the mode_context update strategy to prevent small counts from
skewing the probability distributions.

Tests on derf set showed a small gain:  .06% in psnr and .09% in ssim

Change-Id: Ic812e64ae5f70251c170b0717f7b7fa587055488

Cleanup and switch to Q extended at low end too.

Change-Id: Ie22676bb9e961097d75dbd1d81745208b63e5f4b

This commit extends the number of Q steps to 256 from 128.
The q_trans[] array has been altered to distribute available Q index values
(using the current 64 steps available as input parameters) evenly across the
available range. This is coupled with the fact that each Q step where possible
now equates to a fixed % change in the quantizer. This may want refinement
later especially in terms of the granularity at the high quality end but is a
reasonable starting point.

Change-Id: I2aaa6874fa10ce05c958dd182947ce39f6f1eecb

High Q end extended a little.
Some clean up.

Slightly better on SSIM, Slightly worse on PSNR over derf set.

Change-Id: I3dceea8a39e11c26e1a389a40e40b86efc76d28c

Added code to support 256 index steps instead of 128 but disabled for now.
Replace hard wired table vp8cx_base_skip_false_prob[128]
Observed Qindex problem with setting minimum loop filter value.
(Experiment code using real Q in place but for now just returning 0. This has a big
beneficial effect on some clips, particularly waterfall which shows 5% ssim gain)

Change-Id: I2f7117de8adc1797164c106aa13effc900a1467e

Whilst the encoder explicitly set the segment_id to 0
when segmentation is diabled, the decoder would allow
the segment_id to persist from the previous frame.

This fix attempts to make the decoder behave the same
as the encoder by explicitly setting the segment_id to
0 in this case.

Change-Id: I65c3a05247550edb10706eb5d54d306dfb792309

mode_info_context is padded with an additional column of data, so
mode_info_stride should be used to move between rows rather than
mb_cols.

Change-Id: I598559a2cd9df1c486d64aaeccf76b76a7ecf21c

Both encoder & decoder were using mb_cols to
offset from one row of MODE_INFO structures to the next
when they should have been using mode_info_stride.

Fixing this in both encoder and decoder gives around
a 3KB size saving and 0.025dB PSNR improvement on the one
720P clip I tried.

(Also removed "index" which was being updated but not used)

Change-Id: I413bea802b142886bfcf8d8aa7f5a2f0c524fd4b

Removed a couple more fixed tables for the extended quantizer experiment
that depend on QINDEX_RANGE.

Change-Id: I2c15ffc7488c2a2b8d6504e2c4b6b2339799d117

Previously, Y-adaptive UV intra coding only enabled on key frames in
UVINTRA experiment. This commit enabled the same coding for inter
frames, so the encoding of UV intra modes are consistent cross all
frame types. Tests on derf set showed a very small overall gain around
.04%:

http://www.corp.google.com/~yaowu/no_crawl/interUVintra.html

The gain looks to be reasonable given inta coded MBs is only a
small portion of MBs in inter frames.

Change-Id: Ic6fc261923f2c253f4a0c9f8bccf4797557b9e16

update_mbgraph_frame_stats used xd->mode_info_context
before it had been setup, resulting in potentially
random accesses of uninitialized memory.

This fix allocates a local MODE_INFO structure to hold
the data generated in the function.

Change-Id: Ic9e75610008ce0e2d690e8e583c21582fee6fc45

A previous commit 76feb965 made the vp8_mode_context adaptive on a frame
frame basis, this commit further made the coding context adaptive to two
frame types separately. Tests on derf set showed a further small gain on
all metrics: avg psnr 0.10%, glb psnr: 0.11%, ssim: 0.08%

http://www.corp.google.com/~yaowu/no_crawl/newNearMode_1209.html

Change-Id: I7b3e32ec8729de1903d14a3f1213f1624b78cdee

Experiment with old Q range but new higher precision quantizer
and transform code.

Change-Id: Id1ff4cb433e5775d709d0133e2aec0322975c292

The commit fixed a problem by capping cpi->active_best_quality to be
smaller than cpi->worst_quality.  Also fixed a few line of code that
was misplaced.

Change-Id: Ie908264b72140c669122a0afde5d886619c33474

This commit removed the macro CONFIG_MULCONTEXT, which was used to
indicate the experiment code for using separate context for altref
and normal frames. This commit made the change fully merged in.

Change-Id: I525f927f68e2365d37b340ef23b836a136a4f70b

This commit removed the macro CONFIG_I8X8, which was used to indicate
the 8x8 intra prediction experiment, made the change fully merged in.

Change-Id: Iafa4443781ce6e83f5591c12ba615a0e92ce0ea0

vp8_mode_contexts[] is an entropy table used to code inter mode
choices. It was a fixed constant table. This commit made the entropy
context adaptive. Tests on derf set showed very good consistent gains
on all metrics: avg psnr .47%, overall psnr .46% and ssim .40%.

http://www.corp.google.com/~yaowu/no_crawl/newModeContext.html

Change-Id: Ia62b14485c948e2b74586118619c5eb2068b43b2

The MODE_STATS macro was used to #ifdef around code for mode entropy
stats collection, this commit fixed a crash when MODE_STATS is on.
The commit also changed a number of array definitions to use defined
macros instead of hard-coded numbers.

Change-Id: I114592f53a1e44e31e455f5725f036ae6168735a

fixed issues caused by conflicts between two experiments.

Change-Id: I56a9bd69493e4850c121ea057a6233c55777c2a5

Because the variable doesn't distinguish between DC and non-DC
prediction, but rather between 16x16 or 4x4 prediction.

Change-ID: Ia4e7dda2bd6230c91515072e3277be2d64e42629

Change-Id: I5f9fc894e6a332d9be6d7336c7c5fe11e65b8498

This patch introduces the concept of dual inter16x16 prediction. A
16x16 inter-predicted macroblock can use 2 references instead of 1,
where both references use the same mvmode (new, near/est, zero). In the
case of newmv, this means that two MVs are coded instead of one. The
frame can be encoded in 3 ways: all MBs single-prediction, all MBs dual
prediction, or per-MB single/dual prediction selection ("hybrid"), in
which case a single bit is coded per-MB to indicate whether the MB uses
single or dual inter prediction.

In the future, we can (maybe?) get further gains by mixing this with
Adrian's 32x32 work, per-segment dual prediction settings, or adding
support for dual splitmv/8x8mv inter prediction.

Gain (on derf-set, CQ mode) is ~2.8% (SSIM) or ~3.6% (glb PSNR). Most
gain is at medium/high bitrates, but there's minor gains at low bitrates
also. Output was confirmed to match between encoder and decoder.

Note for optimization people: this patch introduces a 2nd version of
16x16/8x8 sixtap/bilin functions, which does an avg instead of a
store. They may want to look and make sure this is implemented to
their satisfaction so we can optimize it best in the future.

Change-ID: I59dc84b07cbb3ccf073ac0f756d03d294cb19281

Resolved or factored out some further issues with Q index.
Put in a 3rd order polynomial instead of less accurate power function
as the best fit on gf and kf boost adjustment.
Added avg_q value to use instead of ni_av_qi.
Compute segment delta Q values based on avg_q.
Fixed bug in adjust_maxq_qrange().

The extended range Q on the derf set, using standard data rates
(which do not extend high enough to get big benefits) still show
a shortfall of between 0.5 and 1% though so there would appear to
be further issues that need to be tracked down.

Change-Id: Icfd49b9f401906ba487ef1bef7d397048295d959

CNT_INTRA has been used for counting (0,0) motion vectos, this commit
renames it to CNT_ZEROMV

Change-Id: I8f67c5468370090525faf84ba5b3f780d302443f

Change-Id: I17d9c1246d69e102297ec1c3efb359691b3da313

Added two experimental options to the configure script:
1. newnear:
   new scheme of doing mv encoding that include a motion vector from
   last frame in nearest and near mv search
2. mulcontext:
   tracks entropy context separately for regular frames and alt ref
   frames.

Change-Id: If6e0d5d593351707b497a26eb6a763e080f77e6f

This commit added code to keep track of separate entropy contexts for
normal frames and alt ref frames. The underly assumption was that the
two type of frames have different entropy characteristics given they
typically have quite different quantization levels. By keeping entropy
contexts separate, it helps the entropy context distribution to be more
closely adapted to each frame type.

Tests on derf set showed a good and very consistent gain on all clips
on all metrics, avg psnr: 0.89%, overall psnr: 0.84% and ssim 0.93%.

http://www.corp.google.com/~yaowu/no_crawl/mulcontext.html

Change-Id: I15bc9697f6ff7829042911fe0c62930585d7e65d

This commit enabled the usage of 8x8 intra prediction modes on inter
frames. There are a few TODO items related to this: 1)baseline entropy
need be calibrated; 2)cost of UV need to be done more properly rather
than using decision only relying on Y; 3)Threshold for allowing picking
8x8 intra prediction should be lowered to lower than the B_PRED.

Even with all the TODOs, tests showed consistent gain on derf set ~0.1%
(PSNR:0.08% and SSIM:0.14%). It is assumed that 8x8 intra prediction
will help more on large resolution clips, especially with above TODOs
addressed.

Change-Id: I398ada49dfc32575cfab962a569c2885111ae3ba

Fixed some further QIndex related issues and replaced some tables
(eg zbin and rounding)

Also Added function (currently disabled by default) to populate the
main AC and DC quantizer tables. Using the original AC range the
resulting computed DC values give behavior broadly comparable
on the DERF set. That is not to say that the equations will hold good
over a more extended range. The purpose of this code is to make it
easier to experiment with further alterations to the Q range and distribution
of Q values plus the relative weights given to AC and DC.

The function find_fp_qindex() ensures that changes to the Q tables
are reflected in the value passed in to the first pass code.

Slight experimental adjustment to static segment Q offset.

Change-Id: I36186267d55dfc2a3d565d0cff7218ef300d1cd5

Change-Id: I95fab6f51967008acf1bc9e98fdb7bb56974807f

this commit is to add an variable in the macroblock level mode
info structure to track the transform size used in each MB, so
the information can be used later in the loop filter to change
how loop filter works on MBs with different transform sizes.

Change-Id: Id0eeaba6cc854c6d1be00ed8d237b3d9e250e447