Change-Id: I7549e424ca6846b07a796f2b9cd4e9d4e550ca9b

In summary, this commit encompasses a series of changes in attempt to
improve the 8x8 transform based coding to help overall compression
quality, please refer to the detailed commit history below for what
are the rationale underly the series of changes:

a. A frame level flag to indicate if 8x8 transform is used at all.
b. 8x8 transform is not used for key frames and small image size.
c. On inter coded frame, macroblocks using modes B_PRED, SPLIT_MV
and I8X8_PRED are forced to using 4x4 transform based coding, the
rest uses 8x8 transform based coding.
d. Encoder and decoder has the same assumption on the relationship
between prediction modes and transform size, therefore no signaling
is encoded in bitstream.
e. Mode decision process now calculate the rate and distortion scores
using their respective transforms.

Overall test results:
1. HD set
http://www.corp.google.com/~yaowu/no_crawl/t8x8/HD_t8x8_20120206.html
(avg psnr: 3.09% glb psnr: 3.22%, ssim: 3.90%)
2. Cif set:
http://www.corp.google.com/~yaowu/no_crawl/t8x8/cif_t8x8_20120206.html
(avg psnr: -0.03%, glb psnr: -0.02%, ssim: -0.04%)
It should be noted here, as 8x8 transform coding itself is disabled
for cif size clips, the 0.03% loss is purely from the 1 bit/frame
flag overhead on if 8x8 transform is used or not for the frame.

---patch history for future reference---
Patch 1:
this commit tries to select transform size based on macroblock
prediction mode. If the size of a prediction mode is 16x16, then
the macroblock is forced to use 8x8 transform. If the prediction
mode is B_PRED, SPLITMV or I8X8_PRED, then the macroblock is forced
to use 4x4 transform. Tests on the following HD clips showed mixed
results: (all hd clips only used first 100 frames in the test)

http://www.corp.google.com/~yaowu/no_crawl/t8x8/hdmodebased8x8.html
http://www.corp.google.com/~yaowu/no_crawl/t8x8/hdmodebased8x8_log.html

while the results are mixed and overall negative, it is interesting to
see 8x8 helped a few of the clips.

Patch 2:
this patch tries to hard-wire selection of transform size based on
prediction modes without using segmentation to signal the transform size.
encoder and decoder both takes the same assumption that all macroblocks
use 8x8 transform except when prediciton mode is B_PRED, I8X8_PRED or
SPLITMV. Test results are as follows:

http://www.corp.google.com/~yaowu/no_crawl/t8x8/cifmodebase8x8_0125.html
http://www.corp.google.com/~yaowu/no_crawl/t8x8/hdmodebased8x8_0125log.html

Interestingly, by removing the overhead or coding the segmentation, the
results on this limited HD set have turn positive on average.

Patch 3:
this patch disabled the usage of 8x8 transform on key frames, and kept the
logic from patch 2 for inter frames only. test results on HD set turned
decidedly positive with 8x8 transform enabled on inter frame with 16x16
prediction modes: (avg psnr: .81% glb psnr: .82 ssim: .55%)

http://www.corp.google.com/~yaowu/no_crawl/t8x8/hdintermode8x8_0125.html
results on cif set still negative overall

Patch 4:
continued from last patch, but now in mode decision process, the rate and
distortion estimates are computed based on 8x8 transform results for MBs
with modes associated with 8x8 transform. This patch also fixed a problem
related to segment based eob coding when 8x8 transform is used. The patch
significantly improved the results on HD clips:

http://www.corp.google.com/~yaowu/no_crawl/t8x8/hd8x8RDintermode.html
(avg psnr: 2.70% glb psnr: 2.76% ssim: 3.34%)
results on cif also improved, though they are still negative compared to
baseline that uses 4x4 transform only:
http://www.corp.google.com/~yaowu/no_crawl/t8x8/cif8x8RDintermode.html
(avg psnr: -.78% glb psnr: -.86% ssim: -.19%)

Patch 5:
This patch does 3 things:
a. a bunch of decoder bug fixes, encodings and decodings were verified
to have matched recon buffer on a number of encodes on cif size mobile and
hd version of _pedestrian.
b. the patch further improved the rate distortion calculation of MBS that
use 8x8 transform. This provided some further gain on compression.
c. the patch also got the experimental work SEG_LVL_EOB to work with 8x8
transformed macroblock, test results indicates it improves the cif set
but hurt the HD set slightly.

Tests results on HD clips:
http://www.corp.google.com/~yaowu/no_crawl/t8x8/HD_t8x8_20120201.html
(avg psnr: 3.19% glb psnr: 3.30% ssim: 3.93%)

Test results on cif clips:
http://www.corp.google.com/~yaowu/no_crawl/t8x8/cif_t8x8_20120201.html
(avg psnr: -.47% glb psnr: -.51% ssim: +.28%)

Patch 6:
Added a frame level flag to indicate if 8x8 transform is allowed at all.
temporarily the decision is based on frame size, can be optimized later
one. This get the cif results to basically unchanged, with one bit per
frame overhead on both cif and hd clips.

Patch 8:
Rebase and Merge to head by PGW.
Fixed some suspect 4s that look like hey should be 64s in regard
to segmented EOB. Perhaps #defines would be bette.
Bulit and tested without T8x8 enabled and produces unchanged
output.

Patch 9:
Corrected misalligned code/decode of "txfm_mode" bit.
Limited testing for correct encode and decode with
T8x8 configured on derf clips.

Change-Id: I156e1405d25f81579d579dff8ab9af53944ec49c

Change-Id: Ieaaa07c50eae41118596197f6a4d848135946e41

Please see the following public commit for details:
https://gerrit.chromium.org/gerrit/#change,7608

Change-Id: I589eed0b6078e2c5c9c74e942886e503bd02b273

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

for SPLITMV and B_PRED modes.  Modified code to use the bmi
found in mode_info_context instead of BLOCKD.  On the decode
side, the uvmvs are calculated only when required, instead of
every macroblock.  This is WIP. (bmi should eventually be
removed from BLOCKD)
Small performance gains noticed for RT encodes and decodes.(VGA)

Change-Id: I2ed7f0fd5ca733655df684aa82da575c77a973e7

CONFIG_FAST_UNALIGNED is enabled by default. Disable it if it is
not supported by hardware.

Change-Id: I7d6905ed79fed918bca074bd62820b0c929d81ab

With this fix, the experimental branch now builds and encodes correctly
with the following two configure options respectively:
--enable-experimental --enable-t8x8
--enable-experimental

Change-Id: I3147c33c503fe713a85fd371e4f1a974805778bf

Please refer to previous commit messages for detailed info:
https://on2-git.corp.google.com/g/#change,5940
https://on2-git.corp.google.com/g/#change,6045

Change-Id: I8b16992f2f69c5a808ad40a3e32ef589cce7c59d

Code cleanup.

Change-Id: Ic8b0167851116c64ddf08e8a3d302fb09ab61146

The skip flag is never set by the encoder for SPLITMV.

Change-Id: I5ae6457edb3a1193cb5b05a6d61772c13b1dc506

Code cleanup.  The build inter predictor functions are
redundantly checking the mode_info_context for either
INTRA_FRAME or SPLITMV.

Change-Id: I4d58c3a5192a4c2cec5c24ab1caf608bf13aebfb

A large number of functions were defined with external linkage, even
though they were only used from within one file. This patch changes
their linkage to static and removes the vp8_ prefix from their names,
which should make it more obvious to the reader that the function is
contained within the current translation unit. Functions that were
not referenced were removed.

These symbols were identified by:

  $ nm -A libvpx.a | sort -k3 | uniq -c -f2 | grep ' [A-Z] ' \
    | sort | grep '^ *1 '

Change-Id: I59609f58ab65312012c047036ae1e0634f795779

This eliminates a large set of warnings exposed by the Mozilla build
 system (Use of C++ comments in ISO C90 source, commas at the end of
 enum lists, a couple incomplete initializers, and signed/unsigned
 comparisons).
It also eliminates many (but not all) of the warnings expose by newer
 GCC versions and _FORTIFY_SOURCE (e.g., calling fread and fwrite
 without checking the return values).
There are a few spurious warnings left on my system:

../vp8/encoder/encodemb.c:274:9: warning: 'sz' may be used
 uninitialized in this function
gcc seems to be unable to figure out that the value shortcut doesn't
 change between the two if blocks that test it here.

../vp8/encoder/onyx_if.c:5314:5: warning: comparison of unsigned
 expression >= 0 is always true
../vp8/encoder/onyx_if.c:5319:5: warning: comparison of unsigned
 expression >= 0 is always true
This is true, so far as it goes, but it's comparing against an enum,
 and the C standard does not mandate that enums be unsigned, so the
 checks can't be removed.

Change-Id: Iead6cd561a2afaa3d801fd63f1d8d58953da7426

This eliminates a large set of warnings exposed by the Mozilla build
 system (Use of C++ comments in ISO C90 source, commas at the end of
 enum lists, a couple incomplete initializers, and signed/unsigned
 comparisons).
It also eliminates many (but not all) of the warnings expose by newer
 GCC versions and _FORTIFY_SOURCE (e.g., calling fread and fwrite
 without checking the return values).
There are a few spurious warnings left on my system:

../vp8/encoder/encodemb.c:274:9: warning: 'sz' may be used
 uninitialized in this function
gcc seems to be unable to figure out that the value shortcut doesn't
 change between the two if blocks that test it here.

../vp8/encoder/onyx_if.c:5314:5: warning: comparison of unsigned
 expression >= 0 is always true
../vp8/encoder/onyx_if.c:5319:5: warning: comparison of unsigned
 expression >= 0 is always true
This is true, so far as it goes, but it's comparing against an enum, and the C
 standard does not mandate that enums be unsigned, so the checks can't be
 removed.

Change-Id: Iaf689ae3e3d0ddc5ade00faa474debe73b8d3395

Raised by Lei Yang, the Y plane stride was used for UV blocks.
This is clearly a typo. But as the comments in the code suggested
that this port of code has not been used yet, so the typo should
not have created any damage yet.

Change-Id: Iea895edc17469a51c803a8cc6d0fce65a1a7fc2f

Changes 'The VP8 project' to 'The WebM project', for consistency
with other webmproject.org repositories.

Fixes issue #97.

Change-Id: I37c13ed5fbdb9d334ceef71c6350e9febed9bbba

These copies occurred for each macroblock in the encoder and decoder.
Thetemp MB_MODE_INFO mbmi was removed from MACROBLOCKD.  As a result,
a large number compile errors had to be fixed.

Change-Id: I4cf0ffae3ce244f6db04a4c217d52dd256382cf3

When the license headers were updated, they accidentally contained
trailing whitespace, so unfortunately we have to touch all the files
again.

Change-Id: I236c05fade06589e417179c0444cb39b09e4200d

Change-Id: Ieebea089095d9073b3a94932791099f614ce120c