Substantial reworking of the speed vs quality trade offs for
speed 1 and 2.

In this patch I am attempting to freeze the "quality" meaning of
speeds 1 and 2 relative to speed 0 so that in future we can
better evaluate progress.

I am targeting :
Speed 1 quality ~-5% vs speed 0.
Speed 2 quality ~-10% vs speed 0

It is inevitable that quality will still fluctuate a little as we adjust
settings and add new features, but we will attempt to keep as
close as possible to these values. Above speed 2 things will remain
a bit more fluid for now.

In this patch speed 1 is approximately 4-5x as fast as speed 0. This
is similar to before but the quality hit is a lot less. Likewise speed 2
is approximately 2x as fast as speed 1 but is similar in quality to the
previous speed 1 configuration.

Also slight change to behavior of FLAG_EARLY_TERMINATE to insure
all reference frames get at least one rd test. Important for very low
variance regions.

WIP :- Added a new speed level with old speed 4 becoming speed 5.
Speed 3 and 4 tradeoffs still WIP

Change-Id: Ic7a38dd7b5b63ab1501f9352411972f480ac6264

This commit causes use last partition to consider whether a 64x64 has
motion that might make a new partitioning worth while.

Change-Id: I3a57bedef4f3cd961fadbfa96651c206fa36da4a

Also renaming mb_row -> mi_row, mb_col -> mi_col arguments and calculate
mb_rows/mb_cols values from mi_rows/mi_cols.

Change-Id: I6919a279f560648e23bc9a12f507d17c21ffd5d7

Make encoder skip rectangular partition check in speed 1 and above,
when early termination was triggered in partition split.
Thanks Guillaume (gmartres@) for catching this issue.

This change makes bus_cif at 2000kbps speed 1 runtime goes down from
25612ms to 23438ms (about 9% speed-up), at the expense of -0.235%
performance down.

Change-Id: I98613fad081a261d30d5fa206f934ca70601c180

The code now takes into account temporal and spatial
information to determine the partition size range, but the
frequency counts have been removed.

The net effect is similar in quality but about 10% faster.

Change-Id: I39a513fb79cec9177b73b2a7218f0da70963ae95

This patch deletes the variance based speed three partitioning.
Speed 3 now uses the same partitioning method as speed 2
but with some stricter conditions.

The speed and quality are now somewhere between speeds 2 and 4
whereas before it was worse in both than speed 4.

Change-Id: Ia142e7007299d79db3ceee6ca8670540db6f7a41

Change-Id: I60dee58a4fd24d3c4f3c101a49d30e217309f43a

Renaming txfm_stepdown_count to tx_stepdown_count and max_txfm_size to
max_tx_size.

Change-Id: Ifc173e22c78240e561a57c4c741b64b1b8fc6fef

Using best_mv[2] array instead of two separate variables.

Change-Id: Iefa0a41f5c42c42f2c66cef26750da68405f0f25

After change of MI context storage , mi_8x8[]  pointer may be null for
a block outside of image border. The commit changes to access the data
only after validation of mi_row and mi_col.

Change-Id: I039c4eb486a228ea9d8e5f35ab9ae6717d718bf3

This commit enables forcing all coefficients zero per transformed
block, when its rate-distortion cost is lower than regular coeff
quantization.

The overall performance improvement (including its parent patch on
calculating rd cost per transformed block) at speed 1:
derf:  0.298%
yt:    0.452%
hd:    0.741%
stdhd: 0.006%

Change-Id: I66005fe0fd7af192c3eba32e02fd6d77952accb5

Change-Id: I584fe50f73879f6a72fada45714ef80893b6d549

Change-Id: I76f440a917832c02d7a727697b225bac66b99f56

Change-Id: I16633269582a640809dca27572bbe99efa6369fc

The commit added reset of pred_mv at the beginning of each SB64x64
partition mv search, also limited the usage of pred_mv only when
search on the largest partition is already done. This is to fix
a crash at speed 1/2 encoder where an invalid mv is used in mv
search.

Change-Id: I39010177da76d054e3c90b7899a44feb2e3a5b1b

This commit enables adaptive constraint on motion search range for
smaller partitions, given the motion vectors of collocated larger
partition as a candidate initial search point.

It makes speed 0 runtime of bus at CIF and 2000 kbps goes from
167s down to 162s (3% speed-up), at 0.01dB performance gains. In
the settings of speed 1, this makes the runtime goes from 33687 ms
to 32142 ms (4.5% speed-up), at 0.03dB performance gains.

Compression performance wise, it gains at speed 1:
derf  0.118%
yt    0.237%
hd    0.203%
stdhd 0.438%

Change-Id: Ic8b34c67810d9504a9579bef2825d3fa54b69454

mode_info_context was stored as a grid of MODE_INFO structs.
The grid now constists of pointers to MODE_INFO structs.  The
MODE_INFO structs are now stored as a stream (decoder only),
eliminating unnecessary copies and is a little more cache
friendly.

Change-Id: I031d376284c6eb98a38ad5595b797f048a6cfc0d

If the current obtained distortion is very small, which happens
for static image case, we pick the current partition type without
further split checking.

This won't affect regular videos. For static videos, we got 10%~12%
encoding speed gain. PSNR was better for some clips, and worse for
others. Overall it was even.

Change-Id: If787a57bedf46fc595ca4f5ded2b0c0a69e9fdef

A previous speed feature skipped modes not used in earlier
partitions but this not longer worked as intended following
changes to the partition coding order and in conjunction
with some other speed features (Especially speed 2 and above).

This modified mode skip feature sets a mask after the first X
modes have been tested in each partition depending on the
reference frame of the current best case.

This patch also makes some changes to the order modes are
tested to fit better with this skip functionality.

Initial testing suggests speed and rd hit count improvements
of up to 20% at speed 1. Quality results. (derf -1.9%, std hd  +0.23%).

Change-Id: Idd8efa656cbc0c28f06d09690984c1f18b1115e1

Added check that the returned max and minimum are
valid in bottom and right border cases.

Change-Id: I2d6cdc9b5f04c7d0ff512ddcf3228331e028bf9b

Initialize the probability model context with default value in
encode_sb.

Change-Id: Id826114024dfc21c7ef41aea9f4a0316d4a5cb95

This reverts commit dae17734

Encode crashes, leaks and increases integer overflow errors.

Change-Id: I595aa2649bb8d0b6552ff91652837a74c103fda2

Change-Id: Ifc9da470358f58e800e3d0d70a565b61e5f7834a

mode_info_context was stored as a grid of MODE_INFO structs.
The grid now constists of a pointer to a MODE_INFO struct and
a "in the image" flag.  The MODE_INFO structs are now stored
as a stream, eliminating unnecessary copies and is a little
more cache friendly.

For the test clips used, the decoder performance improved
by ~4.3% (1080p) and ~9.7% (720p).

Patch Set 2: Re-encoded clips with latest. Now ~1.7% (1080p)
and 5.9% (720p).

Change-Id: I846f29e88610fce2523ca697a9a9ef2a182e9256

Speed 4 fixed partition size. Use fixed size unless it does not
fit inside image, in which case use the largest size that does.

Change-Id: I250f7a80506750dd82ab355721624a1344247223

Switching from mi_{width, height}_log2 and b_{width, height}_log2 to
num_8x8_blocks_{wide, high} and num_4x4_blocks_{wide, high}. Removing
redundant code, adding const.

Change-Id: Iaab2207590fd24d0b76999071778d1395dc5cd5d

Change-Id: I752e374867d459960995b24d197301d65ad535e3

Change-Id: I62bb07c377f947cb72fac68add7a6b199e42c6b9

Change-Id: I8a246b3d056c98be614d05a90bc261e2441ffc10

Change-Id: I481d9bb2fa3ec72b6a83d5f04d545ad8013f295c

I've already renamed d27_predictor to d207_predictor but forgot about the
corresponding constant.

Change-Id: Id312aa80fc5b5a1ab8a709a33418a029552a6857

Previous change c4048dbd limits the mv search range assuming max block
size of 64x64, this commit change the search range using actual block
size instead.

Change-Id: Ibe07ab02b62bf64bd9f8675d2b997af20a2c7e11

Put rectangular partition check flag change according to the rd
costs of NONE and SPLIT partition types under the speed feature.

Change-Id: If681e1e078a8d43d86961ea4b748da5cd1b6c331

Removing unused get_sbuv_perpixel_variance function, using has_second_ref/
is_inter_block functions, organizing includes.

Change-Id: I016de4af12fbbb8b4ece26a70759b2392651b095

gets rid of a mix of styles

Change-Id: I3591d312157bc6f53a25438bf047765c671fd8a8

This commit changes the partition search order of superblocks from
{SPLIT, NONE, HORZ, VERT} to {NONE, SPLIT, HORZ, VERT} for
consistency with that of sub8x8 partition search. It enable the use
of early termination in partition search for all block sizes.

For ped_area_1080p 50 frames coded at 4000 kbps, it makes the runtime
goes down from 844305ms -> 818003ms (3% speed-up) at speed 0.

This will further move towards making the in-search partition types
configurable, hence unifying various speed-up approaches.

Some speed 1 and 2 features are turned off during the refactoring
process, including:
disable_split_var_thresh
using_small_partition_info

Stricter constraints are applied to use_square_partition_only for
right/bottom boundary blocks. Will bring back/refine these features
subsequently. At this point, it makes derf set at speed 1 about
0.45% higher in compression performance, and 9% down in run-time.

Change-Id: I3db9f9d1d1a0d6cbe2e50e49bd9eda1cf705f37c

Adds a couple of minor fixes, which may be absorbed in Jingning's
patch. Thanks to Guillaume for pointing these out.
Also adjusts the thresholds for speed 1 and 2 to 16 and 32
respectively, to keep quality drops small.

Results:
--------
derfraw300:  threshold = 16, psnr -0.082%, speedup 2-3%
             threshold = 32, psnr -0.218%, speedup 5-6%
stdhdraw250: threshold = 16, psnr -0.031%, speedup 2-3%
             threshold = 32, psnr -0.273%, speedup 5-6%

Change-Id: I4b11ae8296cca6c2a9f644be7e40de7c423b8330

It appears that the above/left mb_skip_coeff used during
the pick modes, is left over from the previously
encode frame.  This patch initializes the flag to the default
value of zero.


Change-Id: Ida4684cc99611d6e3e82628db35ed717e28ce550

Using size_group_lookup table and better variable names.

Change-Id: I6e67f2ce091845db43ace7d21b7ae31c6f165aec

Change-Id: I32e43474e8651ef2eb181d24860a8f118cfea7bf