As we are no longer able to sort the candidate
mvrefs in both encoder and decode and given
that the cost of explicit signalling has proved
prohibitive, it no longer makes sense to find more
than 2 candidates.

This patch:

Modifies and simplifies add_candidate_mv()

Removes the forced addition of a 0 vector in the
MAX_MV_REF_CANDIDATES-1 position (in preparation
to reducing MAX_MV_REF_CANDIDATES to 2).

Re-orders the addition of candidates slightly.

This actually gives small gains (circa 0.2% on std-hd)

A subsequent patch will remove NEW_MVREF experiment,
reduce MAX_MV_REF_CANDIDATES to 2 and remove distance
weights as these are implicit now in the order.

Change-Id: I3dbe1a6f8a1a18b3c108257069c22a1141a207a4

Using regular 0 and 1 constants now.

Change-Id: Ie763503cbb727847cc8f1d6506cd6f2ee607f056

Change-Id: I0d12f9ef9d960df0172a1377f8e5236eb6d90492

Change-Id: Ifda91d697c5970c65ce3ec1feac5562124f91782

Fixing function arguments alignment, reusing MIN/MAX and clamp functions.

Change-Id: I87dd5a40ffb65b521b8abbf0fccf2f50552c5309

Removing redundant 'extern' keywords, fixing formatting and #include order,
code simplification.

Change-Id: I0e5fdc8009010f3f885f13b5d76859b9da511758

This patch adds column-based tiling. The idea is to make each tile
independently decodable (after reading the common frame header) and
also independendly encodable (minus within-frame cost adjustments in
the RD loop) to speed-up hardware & software en/decoders if they used
multi-threading. Column-based tiling has the added advantage (over
other tiling methods) that it minimizes realtime use-case latency,
since all threads can start encoding data as soon as the first SB-row
worth of data is available to the encoder.

There is some test code that does random tile ordering in the decoder,
to confirm that each tile is indeed independently decodable from other
tiles in the same frame. At tile edges, all contexts assume default
values (i.e. 0, 0 motion vector, no coefficients, DC intra4x4 mode),
and motion vector search and ordering do not cross tiles in the same
frame.
t log

Tile independence is not maintained between frames ATM, i.e. tile 0 of
frame 1 is free to use motion vect...

Quality / decode speed trade off changes.
Simpler insert method without sort. Quality impact small.

Change-Id: Id0c0941bc508d985405abd06a13ffe7489170b62

Adds an error-resilient mode where frames can be continued
to be decoded even when there are errors (due to network losses)
on a prior frame. Specifically, backward updates are turned off
and probabilities of various symbols are reset to defaults at
the beginning of each frame. Further, the last frame's mvs are
not used for the mv reference list, and the sorting of the
initial list based on search on previous frames is turned off
as well.

Also adds a test where an arbitrary set of frames are skipped
from decoding to simulate errors. The test verifies (1) that if
the error frames are droppable - i.e. frame buffer updates have
been turned off - there are no mismatch errors for the remaining
frames after the error frames; and (2) if the error-frames are non
droppable, there are not only no decoding errors but the mismatch
PSNR between the decoder's version of the post-error frames and the
encoder's version is at least 20 dB.

Change-Id: Ie6e2bcd436b1e8643270356d3a930e8...

Change-Id: I0df99742029834a85c4933652b0587cf5b6b2587

3.2% gains on std/hd, 1.0% gains on hd.

Change-Id: I481d5df23d8a4fc650a5bcba956554490b2bd200

This experimental change reorders the search so
that all possible references that match the target
reference frame are tested first and these in order
of distance from the current block. These will usually
be the highest scoring candidates.

If we do not find enough good candidates this way
we try non matching cases. These will usually be lower
scoring candidates.

The change in order together with breakouts when
we have found enough candidates should reduce
the computational cost and especially reduce the number
of sort operations.

Quality Results:
Std Hd +0.228%, Hd +0.074%, YT +0.046%, derf +0.137%

This effect is probably due to the fact that more distant
weak candidates are now less likely to get "promoted" over
near candidates even if they are repeated.

Change-Id: Iec37e77d88a48ad0ee1f315b14327a95d63f81f6

This patch reduces the cpu cost of the MV ref
search by only allowing insert for candidates
that would be in the current top 4.

This could alter the outcome and slightly favors
near candidates which are tested first but also
limits the worst case loop count to 4 and means in
many cases it will drop out and not happen.

Change-Id: Idd795a825f9fd681f30f4fcd550c34c38939e113

This patch allows use of 8x8 and 4x4 ADST correctly for Intra
16x16 modes and Intra 8x8 modes when the block size selected
is smaller than the prediction mode. Also includes some cleanups
and refactoring.

Rebase.

Change-Id: Ie3257bdf07bdb9c6e9476915e3a80183c8fa005a

Change-Id: Ia1cce221f8511561b9cbd8edb7726fbc286ff243

Support for gyp which doesn't support multiple objects in the same
static library having the same basename.

Change-Id: Ib947eefbaf68f8b177a796d23f875ccdfa6bc9dc

Experiments with a larger set of contexts and some
clean up to replace magic numbers regarding the
number of contexts.

The starting values and rate of backwards adaption
are still suspect and based on a small set of tests.
Added forwards adjustment of probabilities.

The net result of adding the new context and forward
update is small compared to the old context from the
legacy find_near function.  (down a little on derf but
up by a similar amount for HD)

HOWEVER.... with the new context and forward update
the impact of disabling the reverse update (which may be
necessary in some use cases to facilitate parallel decoding)
is hugely reduced.

For the old context without forward update, the impact of
turning off reverse update (Experiment was with SB off) was
Derf - 0.9, Yt -1.89, ythd -2.75 and sthd -8.35. The impact was
mainly at low data rates.

With the new context and forward update enabled the impact
for all the test sets was no more than 0.5-1% (again most at
the low end).

Change-Id: Ic751b414c8ce7f7f3ebc6f19a741d774d2b4b556

added additional motion vectors at close neighborhood of a superblock
to the list of candiate motion vectors, and removed a couple that are
further away.

The change helped std-hd set about .8% (all metrics) and smaller gain
for derf set.

Change-Id: Iaa69b98614db43420ed3fd4738d0ca5587b90045

A patch on compound inter-intra prediction.

In compound inter-intra prediction, a new predictor for
16x16 inter coded MBs are obtained by combining a single
inter predictor with a 16x16 intra predictor, in a manner
that the weight varies with distance from the top/left
boundary. The current search strategy is to combine the best
inter mode with the best intra mode obtained independently.

Results so far:

derf +0.31%
yt +0.32%
std-hd +0.35%
hd +0.42%

It is conceivable that the results would improve somewhat
with a more thorough search strategy where all intra modes
are searched given the best mv, or even a joint search for
the best mv and the best intra mode.

Change-Id: I7951f1ed0d6eb31ca32ac24d120f1585bcd8d79b

This change is a fix / extension of the newbestrefmv
experiment. As such it is presented without IFDEF.

The change creates a new context for coding inter modes
in vp9_find_mv_refs(). This replaces the context that
was previously calculated in vp9_find_near_mvs().
The new context is unoptimized and not necessarily
any better at this stage (results pending), but eliminates
the need for a legacy call to vp9_find_near_mvs().
Based on numbers from Scott, this could help decode
speed by several %.

In a later patch I will add support for forward update of
context (assuming this helps) and refine the context as
necessary.

Change-Id: I1cd991b82c8df86cc02237a34185e6d67510698a

Experiment to test speed trade off of reducing the
extent of the ref mv search.

Reducing the maximum number of tested candidates to 9 had
minimal net effect on quality in any of the tests sets.

Reduction to 7 has a small negative impact (worst was STD-HD
at about -0.2%).

This change is in response to the apparently high number of
decode cycles reported in regard to mv-ref selection.

Change-Id: I0e92e92e324337689358495a1ec9ccdeb23dc774

Change-Id: Ib39ad47a7d188f3b45416937b7eeb28c3e79b74c

Change-Id: Ic084c475844b24092a433ab88138cf58af3abbe4

Preparation for project restructuring.
Added vp9_ prefix on some function names that have global scope.
Added static declaration on some that dont.

Change-Id: If072f78b4300e8c17cfeed82c5d17b59946dcc5e

This commit merges those parts of the CONFIG_NEW_MVREF
that specifically relate to choosing a better set of candidate
MV references into the NEWBESTREFMV experiment.

CONFIG_NEW_MVREF will then be used for changes relating
to the explicit coding of a cost optimized MV reference in the
bitstream as part of MV coding.

Change-Id: Ied982c0ad72093eab29e38b8cd74d5c3d7458b10

Extend experiment to use both vectors from MBs
coded using compound prediction as candidates.

In final sort only consider best 4 candidates
for now but make sure 0,0 is always one of them.

Other minor changes to new MV reference code.
Pass in Mv list to vp8_find_best_ref_mvs().

Change-Id: Ib96220c33c6b80bd1d5e0fbe8b68121be7997095

Alternative strategy for finding a list of candidate motion
vectors to use as reference values in mv coding and as
nearest and near.

Sort by sad in vp8_find_best_ref_mvs() rather than just
pick the best. Allow 0,0 as a best ref option but not a
nearest or near unless there are no alternatives.

Encode/Decode verified on at least some clips.

Some commented out experimental and stats code still in place.

Gain over existing code averages about 1% on derf (alll metrics)
with improvement on all clips. Other test results pending.

The entropy coding of the mode (nearest/near etc) still
depends upon and requires the old "findnear" code so
this needs looking at and may provide room for further gains.

Change-Id: I871d7cba1d1c379c4bad9bcccce1fb19c46b8247