Replaces the default tables for single coefficient magnitudes with
those obtained from an appropriate distribution. The EOB node
is left unchanged. The model is represeted as a 256-size codebook
where the index corresponds to the probability of the Zero or the
One node. Two variations are implemented corresponding to whether
the Zero node or the One-node is used as the peg. The main advantage
is that the default prob tables will become considerably smaller and
manageable. Besides there is substantially less risk of over-fitting
for a training set.

Various distributions are tried and the one that gives the best
results is the family of Generalized Gaussian distributions with
shape parameter 0.75. The results are within about 0.2% of fully
trained tables for the Zero peg variant, and within 0.1% of the
One peg variant.

The forward updates are optionally (controlled by a macro)
model-based, i.e. restricted to only convey probabilities from the
codebook. Backward updates can also be optionally (controlled by
another macro) model-based, but is turned off by default. Currently
model-based forward updates work about the same as unconstrained
updates, but there is a drop in performance with backward-updates
being model based.

The model based approach also allows the probabilities for the key
frames to be adjusted from the defaults based on the base_qindex of
the frame. Currently the adjustment function is a placeholder that
adjusts the prob of EOB and Zero node from the nominal one at higher
quality (lower qindex) or lower quality (higher qindex) ends of the
range. The rest of the probabilities are then derived based on the
model from the adjusted prob of zero.

Change-Id: Iae050f3cbcc6d8b3f204e8dc395ae47b3b2192c9

As things stand the zero bin mode boost is hurting somewhat.
In part this seems to be because the boost applied as is
interferes with the rd mode selection loop.

Average gains (derf 0.072, yt 0.243, ythd 0.179 std-hd 0.212%)

Change-Id: Icaecea3908d9a7352370e49b8fa822f2c2c49dc1

Change-Id: Ifa864e0acb253b238b03cdeed0fe5d6ee30a45d8

Wrote sse2 version of vp9_short_idct10_16x16 function. Compared
to c version, the sse2 version is 2.3X faster.

Change-Id: I314c4f09369648721798321eeed6f58e38857f26

Wrote sse2 version of vp9_short_idct16x16 function. Compared to c
version, the sse2 version is over 2.5X faster.

Change-Id: I38536e2b846427a2cc5c5423aaf305fd0e605d61

Renaming Width to width, Height to height and Version to version in
several structs and function signatures.

Change-Id: I084c3f7e747cb2ce3345aff27a3dff9b13a87543

Change-Id: I0d226e4cb240caced37230f46905bf69b46e0cce

Specifically changes to retain more precision
especially at low Q through to the point of use.

Change-Id: Ief5f010f2ca4daaabef49520e7edb46c35daf397

Change-Id: I9b4cb1e2ce6c6a99cffd473ff2fa7579bd318fcd

Wrote sse2 functions of vp9_short_idct8x8 and vp9_short_idct10_8x8.
Compared to c version, the sse2 version is 2X faster. The decoder
test didn't show noticeable gain since 8x8 idct doesn't take much
of decoding time (less than 1% in my test).

Change-Id: I56313e18cd481700b3b52c4eda5ca204ca6365f3

Update to +/- 1dB.

Change-Id: Idada001f261b36945c9334e288a415ee2c79c415

If the intended display size is different than the size the frame is
coded at, then send that size explicitly in the bitstream. Adds a new
bit to the frame header to indicate whether the extra size fields
are present.

Change-Id: I525c66f22d207efaf1e5f903c6a2a91b80245854

Adjust the filter length and strength for each
ARF group based on a measure of difficulty (the boost)
and the active q range.

Remove lower limit on RDMULT value.

Average gains on the different sets in range 0.4%-0.9%.
However the ARNR changes give a very big boost on a
few clips.

Eg. Soccer ~5%, in derf set and Cyclist ~ 10% in the std-hd set

Change-Id: I2078d78798e27ad2bcc2b32d703ea37b67412ec4

This fix resolves some of the mismatch issues being seen
recently. While this is the right thing to do when tiling
is used for this experiment, it is not the underlying cause
of the the mismatches.
Something else is causing writing outside of the allowable
frame area in the encoder leading to this mismatch.

Change-Id: If52c6f67555aa18ab8762865384e323b47237277

These variables are unused, and are subject to overflowing, causing
assertions when built with -ftrapv.

Change-Id: Ia00a3201af309906c05bcd4b23a643925ed6ea86

If the second reference is better than the first in the long term,
it was possible to try to take the fractional exponent of a
negative number, giving an undefined result.

Change-Id: I1dd08286747ceae960eb03bb5d98a383cc9d253b

Scalar path is about 1.5x faster (3.1% overall encoder speedup).
SSE2 path is about 7.2x faster (7.8% overall encoder speedup).

Change-Id: I06da5ad0cdae2488431eabf002b0d898d66d8289

Moving identical code to separate functions, variable declaration and
initialization on the same line.

Change-Id: Ifa6474a64189f9d8051e88e19850453b0227752c

Change-Id: I25424904fb8541fc19d00d9fbc592379374b98c0

Change-Id: I75fc4eee10bee9efd419d248827290cce8e6d637