The y4m extension used is the same as the one used in ffmpeg/x264.
The patch is adapted from the highbitdepth branch.

Also adds unit tests for y4m header parsing and md5 check
of the raw frame data, as well as y4m writing.

Change-Id: Ie2794daf6dbafd2f128464f9b9da520fc54c0dd6

* changes:
  update vp9_thread.[hc]
  vp9_thread_test: remove unnecessary c_str()'s
  vp9_thread_test: factorize decode loop

This commit re-designs the quantization process for transform
coefficient blocks of size 4x4 to 16x16. It improves compression
performance for speed 7 by 3.85%. The SSSE3 version for the
new quantization process is included.

The average runtime of the 8x8 block quantization is reduced
from 285 cycles -> 255 cycles, i.e., over 10% faster.

Change-Id: I61278aa02efc70599b962d3314671db5b0446a50

Change-Id: I3d95fbe9a8098256582b5386881d5b7bbdb317ed

The current threshold is knid of low, and in many cases NEWMV
mode is checked but not picked as the best mode. This patch
added a speed feature to increase NEWMV threshold, so that
less partition mode checking goes to check NEWMV. This feature
is enabled for speed 6 and 7.

Rtc set borg tests showed:
1. Speed 6, overall psnr: -0.088%, ssim: -1.339%;
   Average speedup on rtc set is 11.1%.
2. Speed 7, overall psnr: -0.505%, ssim: -2.320%
   Average speedup on rtc set is 12.9%.

Change-Id: I953b849eeb6e0d5a1f13eacba30c14204472c5be

Change-Id: Id52a7869fd1f31bb060de170e3295da7435adb9e

Grayscale is conditionally compiled.

Change-Id: I482ab237560d0bae8d397fd9999e78d38104f2a1

This refelects the profile 1 bitstream change in 6c54dbcb.

Change-Id: I39625d88f236a79b7f2955d79c5a451e3753da16

Change-Id: I74fc5f1a7bab3128cdd49441b83ec3a25aee65ca

Fixed the signed/unsigned mismatch.

Change-Id: Id83d603b8f1745b71f4cf695a0751e55518b1316

pull the latest from WebP, which adds a worker interface abstraction
allowing an application to override init/reset/sync/launch/execute/end

this has the side effect of removing a harmless, but annoying, TSan
warning.

Original source:
 http://git.chromium.org/webm/libwebp.git
  100644 blob 08ad4e1fecba302bf1247645e84a7d2779956bc3 src/utils/thread.c
  100644 blob 7bd451b124ae3b81596abfbcc823e3cb129d3a38 src/utils/thread.h

Local modifications:
 - s/WebP/VP9/g
 - camelcase functions -> lower with _'s
 - associate '*' with the variable, not the type

Change-Id: I875ac5a74ed873cbcb19a3a100b5e0ca6fcd9aed

EXPECT_EQ() works with strings

Change-Id: I2b13369d2aa7ff305ee516e6cb73bd099f8dead9

+ add a SCOPED_TRACE with the current filename

Change-Id: I9ceb47a9154bc0d9f9878a83b707e8ed935790f9

s/VP9DecodeMTTest/VP9DecodeMultiThreadedTest/

this enables simpler test filtering

Change-Id: I010a451cf32fa5a95db6734cc22f331f0a0d515a

fixes:
vp8\encoder\bitstream.h: same type qualifier used more than once

Change-Id: I62b99342131fdaedb1f7cc8d2dcd13ab34637cd7

The caller should reset the state instead of letting worker
to reset.

This reverts commit 34b2ce15.

Change-Id: Idb546ea6386cffc44e98dee772900d21ab79710f

Encoder still uses SWITCHABLE as default via DEFAULT_INTERP_FILTER,
but does not override the default if it is not SWITCHABLE.

Change-Id: I3c0f6653bd228381a623a026c66599b0a87d01d5

Moved the encode_breakout_test out of vp9_pick_inter_mode().

Change-Id: I6966d0293ae5210a5a28b0e8debacb24d1c0d2d4

When the frame is intra coded only, the encoder takes the RD
coding flow. Hence the function set_mode_info is not practically
in use. This commit removes it and the associated conditional
branches.

Change-Id: I1e42659ceb55b771ba712d1cdecacb446aa6460d

This fixes the hang in VP9/InvalidFileTest.ReturnCode/3
due to worker->had_error has not been reset after getting
error.

Change-Id: Ia3608225094758a2bd88f6ae4dd9dfd93bbaad27

For real time speed 7, once encode breakout is on(i.e. encoding
setting --static-thresh=1), a proper encode breakout threshold
is set to speed up the encoder.

Set --static-thresh=1, RTC set borg test showed a slight overall
psnr loss of 0.162%, but ssim gain of 0.287%. The average speedup
on RTC set is 6%, and for some clips, the speedup can be 10+%.

Change-Id: Id522d9ce779ff7c699936d13d0c47083de4afb85

Before encoding a frame, calculate and store each 16x16 block's
variance of source difference between last and current frame.
Find partitioning threshold T for the frame from its variance
histogram, and then use T to make partition decisions.

Comparing with fixed 16x16 partitioning, rtc set test showed an
overall psnr gain of 3.242%, and ssim gain of 3.751%. The best
psnr gain is 8.653%.

The overall encoding speed didn't change much. It got faster for
some clips(for example, 12% speedup for vidyo1), and a little
slower for others.

Also, a minor modification was made in datarate unit test.

Change-Id: Ie290743aa3814e83607b93831b667a2a49d0932c