this commit changed the UV r/d calculation in the mode decision process to
properly account for the rate of 8x8 transform coefficients.

Change-Id: I485f8f35f2b61db0b6539beb32e83481b1cf083b

Previously, the scaling related to extended quantize range happens in
dequantization stage, which implies the coefficients form forward
transform are in different scale(4x) from dequantization coefficients
This worked fine when there was not distortion computation done based
on 8x8 transform, but it completely wracked the distortion estimation
based on transform coefficients and dequantized transform coefficients
introduced in commit f64725a0 for macroblocks using 8x8 transform.
This commit fixed the issue by moving the scaling into the stage of
inverse 8x8 transform.

TODO: Test&Verify the transform/quantization pipeline accuracy.

Change-Id: Iff77b36a965c2a6b247e59b9c59df93eba5d60e2

Change-Id: I265ad46e01a307bca21e6223725e4055f5e08648

This commmit added logic for MB using dual-pred to compute rate
estimation based on correct transform size. The section of code
was previously located under #if CONFIG_DUALPRED, that was made
to be working with T8x8 experiment at the same time.

Change-Id: Iebc2518c03f11378b9c2e72905520f088b54d5c0

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: Idb328dd29ebcd360e39886abe48694f90f2e1140

Change-Id: Ieaaa07c50eae41118596197f6a4d848135946e41

This commit only involves the removal of placeholder comments
//#if CONFIG_SEGFEATURES.

Change-Id: I94b350daaf998ee0cfdde5aa25b1d3b0522ab816

Merge the extended Q experiment as indicated by the

Change-Id: I02d9e654fff9998cc7e9e2f1f5cd838dad8fb431

Merged in most of the current common prediction changes
that were under the #if CONFIG_COMPRED option.

Change-Id: If4e6f61dbe7b86dd449f6effbe93b5eb7e893885

This commit merges the NEWNEAR experiment such that it
is effectively always on.

The fact that there were changes in the threading code again
highlights the need to strip out such features during the
bitstream development phase as trying to maintain this code
(especially as it is not being tested) slows the development cycle.

Change-Id: I8b34950a1333231ced9928aa11cd6d6459984b65

Initial modifications to make limited use of common prediction
functions.

The only functional change thus far is that updates to the probabilities are
no longer "damped". This was a testing convenience but in fact seems to
help by a little over 0.1% over the derf set.

Change-Id: I8b82907d9d6b6a4a075728b60b31ce93392a5f2e

Moved the prob_dualpred[] sturcture to common.
Created common prediction entry for Dual flag.

Change-Id: I9ac3d128bae6114f09e5c18216d4b95cf36453d5

As a precursor to encoding 32x32 blocks this cl adds the
ability to encode the frame superblock (=32x32 block) at
a time. Within a SB the 4 indiviual MBs are encoded in
raster-order (NW,NE,SW,SE).

This functionality is added as an experiment which can be
enabled by ispecifying --enable-superblocks in the
command line specified to configure (CONFIG_SUPERBLOCKS
macro in the code).

To make this work I had to disable the two intra
prediction modes that use data from the top-right of the
MB.

On the tests that I have run the results produce
almost exactly the same PSNRs & SSIMs with a very
slightly higher average data rate (and slightly higher
data rate than just disabling the two intra modes in
the original code).

NOTE: This will also break the multi-threaded code.

This replaces the abandoned change:
Iebebe0d1a50ce8c15c79862c537b765a2f67e162

Change-Id: I1bc1a00f236abc1a373c7210d756e25f970fcad8

This check in uses the common prediction interface functions
to code reference frame.

Some updates made regarding the impact of the new code in rd loop
but there remain TODOs in this regard.

Change-Id: I9da3ed5dfdaa489e0903ab33258b0767a585567f

changed the token cost for 8x8 transformed macroblock used in trellisquant
from those derived from 4x4 transform coefficient distribution to those
derived from 8x8 transform coefficient distribution. Test results show
this fix help 8x8 transform based compression consistently on cif and hd
sets:

http://www.corp.google.com/~yaowu/no_crawl/t8x8/cif_cost8x8only.html
(avg psnr:.14% glb psnr: .17% ssim: .20%)
http://www.corp.google.com/~yaowu/no_crawl/t8x8/hd_cost8x8only.html
(avg psnr:.17% glb psnr: .18% ssim: .58%)

Note: To test the effect of this change, 8x8 transform was forced to be used
only on 16x16 predicted macroblocks on inter frames, the effect would be
bigger had all macroblocks been forcd to use 8x8 transform.

Change-Id: If9b7868b75357c66541f511e5ee78e4d2d4929a4

This fixed a conflict introduced by the change of adding 8x8 intra
prediction modes. The 8x8 intra prediction mode code assumed the
use of 4x4 transform, and causes encoder crashes when the codec is
configured with --enable-t8x8.

Change-Id: I00cc94df63e9725377ffba9eb51be6b77fe3fcf9

Change-Id: Ifadf65026a11bdb5d39840748613880bcfb364bb

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

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

fixed issues caused by conflicts between two experiments.

Change-Id: I56a9bd69493e4850c121ea057a6233c55777c2a5

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

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

Fixed bug in firspass.c call to vp8_initialize_rd_consts()

This was passing in vp8_dc_quant(cm->base_qindex, cm->y1dc_delta_q)
 instead of (cm->base_qindex + cm->y1dc_delta_q).

It just so happens that for the value 26 used for cm->base_qindex in the
unextended Q case,  the two give similar results. However, when using
the extended Q range the two are very different.

Also added more stats output and partly disabled another broken feature.

Change-Id: Iddf6cf5ea8467c44b7c133f38e629f6ba6f2581e

This is an experiment to include a mv contribution from last frame to
nearest and near mv definition. Initial test showed some small though
consistent gain.

latest patch slightly better result ~.13%-~.18%.

TODO: the entropy used to encode the mode choice, i.e. the mv counts
based conditional distribution of modes should be re-collected to
reflect this change, it is expected that there is some further gain
from that.

Change-Id: Ief1e284a36d8aa56b49ae5b360c91419ec494fa4

This commit resolves further QIndex look up tables to facilitate
experimentation with the quantizer range.

In some cases  rather than remove the look up tables completely
I have created functions that are called once  to populate them
using a formulaic approach base on the actual quantizer.

The use of these functions based on best fit of data from the original
tables does affect the results on some clips but across the derf test
set the effect was broadly neutral.

Change-Id: I8baa61c97ce87dc09a6340d56fdeb681b9345793

Removed unused variables lf_or_gf and frame_lf_or_gf.

Change-Id: I88692cd7d53e532d303c4525ee4667c1ecea3026

One of the problems arising when tweaking or adjusting the quantizer
tables is that there are a lot of look up tables that depend on the QINDEX.
Any adjustment to the link between QINDEX and real quantizer therefore tends
to break aspects of for example the rate control.

In this check in I have replaced several of the look up tables with functions that
approximate the same results as the old Q luts but use a formulaic approach
based on real Q values rather than QIndex. This should hopefully make it easier
to experiment with changes to the Q tables without always having to go through
and hand optimize a set of look up tables. Once things stabilize we may choose
to re-instate luts for the sake of performance.

Patch 2:
    Addressed Ronald's comments.
    vp8_init_me_luts() Added so luts only initialized once.

Change-Id: Ic80db2212d2fd01e08e8cb5c7dca1fda1102be57

Block the selection of 4x4 modes in key frames if 8x8 is selected.

Change-Id: Ie5729ec22a999d9a1996f020bd4b941e29514992

For ease of testing and merging experiments I have
removed in line code in encode_frame() that assigns
MBs to be t8x8 or t4x4 coded segments and have
moved the decision point and segment setup to
the init_seg_features0 test function.

Keeping everything in one place helps make sure
for now that experiments using segmentation are
not fighting each other.

Also made sure mode selection code can't choose 4x4
modes if t8x8 is selected.

Patch2: In init_seg_features() add checks
for SEG_LVL_TRANSFORM active.

Change-Id: Ia1767edd99b78510011d4251539f9bc325842e3a

Bug fix to logic in vp8_pick_inter_mode() and
vp8_rd_pick_inter_mode().

The block on the use of segment features
for the cm->refresh_alt_ref_frame case
was just for testing and is not correct.

The special case code for alt ref can
be re-enabled as an else clause.

Change-Id: Ic9b57cdb5f04ea7737032b8fb953d84d7717b3ce

Initial attempt at using new segment feature signaling
to indicate 4x4 or 8x8 transform.

needs --enable-experimental --enable-t8x8

Note this is work in progress.

Change-Id: Ib160d46a5d810307bfcbc79853ce1a65b5b870b7

No change to functionality or output.

Updates to the segment feature data structure now all done
through functions such as set_segdata() and get_segdata()
in seg_common.c.

The reason for this is to make changing the structures (if needed)
and debug easier.

In addition it provides a single location for subsequent addition
of range and validity checks. For  example valid combination of
mode and reference frame.

Change-Id: I2e866505562db4e4cb6f17a472b25b4465f01add

Removal of configure #ifdefs so that segment features
always available. Removal of code supporting old
segment feature method.

Still a good deal of tidying up to do.

Change-Id: I397855f086f8c09ab1fae0a5f65d9e06d2e3e39f

Modify reference frame segmentation so that ONE or MORE
reference frames may be marked as a available for a given
segment.

Fixed bugs relating to segment coding of INTRA and some
INTER modes at the segment level.

Modified Q boost for static areas based on ambient average Q.

Strong results now on clips with significant static areas.
(some data points in derf set as high as 9% and some static &
slide show type content in YT set > 20%)

Change-Id: Ia79f912efa84b977f35a23683ae3643251e24f0c

This quite large check in includes the following:

Merge in some code from Ronald (mbgraph.c) that scans a Gf/arf group.
This is used as a basis for a simple segmentation for the normal frames
in a gf/arf group. This code also uses satd functions from Yaowu.

Adds functionality for coding the latest possible position of an EOB for
blocks in the segment. (Currently 0-15 only, hence just for 4x4 dct).
Where the EOB position is 0 this acts like "skip" and the normal coding
of skip at the per mb level is disabled.

Added functions (seg_common.c) for setting and reading segment feature
elements. These may want to be optimized away at some point but while the
mecahnism is in a state of flux they provide a single location for making
changes and keep things a bit cleaner.

This is still proof of concept code. Currently the tested feature set:-

Quantizer,
Loop Filter level,
Reference frame,
Prediction Mode,
EOB end stop.

TBD:-

Add functions for setting and reading the feature data with range
and validity checking.

Handling of signed and unsigned feature data. At the moment all is assumed
to be signed and a sign bit is coded but many cannot be negative.

Correct handling of EOB feature with intra coded blocks.

Testing/trapping of legal/illegal ref frame and mode combinations.

Transform size switch plus merge and test with 8c8 DCT work

Merge and test with Sumans Segmenation coding optimizations

Change-Id: Iee12e83661c7abbd1e0ce6810915eb4ec35e2d8e

Proof of concept test code that encodes mode and reference
frame data at the segment level.

Decode-able bit stream but some issues not yet resolved.
As it this helps a little on a couple of clips but hurts on most as
the basis for segmentation is unsound.

To build and test, configure with
--enable-experimental --enable-segfeatures

Change-Id: I22a60774f69273523fb152db8c31f4b10b07c7f4