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
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 fixes encoder/decoder mismatches with the superblock experiment
turned on whenever a superblock is encoded using the 4x4 transform.
Change-Id: Iefec7055e8d25f8efdbba66c4261bbd322d335a3
This should prevent inconsistent results between identical encodes with
the superblock experiment turned on.
Change-Id: I41a005fae53f2eb59736cc70041185fb7d63cfca
Preliminary patch on a new 4x4 intra mode B_CONTEXT_PRED where the
dominant direction from the context is used to encode. Various decoder
changes are needed to support decoding of B_CONTEXT_PRED in conjunction
with hybrid transforms since the scan order and tokenization depends on
the actual direction of prediction obtained from the context. Currently
the traditional directional modes are used in conjunction with the
B_CONTEXT_PRED, which also seems to provide the best results.
The gains are small - in the 0.1% range.
Change-Id: I5a7ea80b5218f42a9c0dfb42d3f79a68c7f0cdc2
Also split superblock handling code out of decode_macroblock() into
a new function decode_superblock(), for easier readability.
Derf +0.05%, HD +0.2%, STDHD +0.1%. We can likely get further gains
by allowing to select mb_skip_coeff for a subset of the complete SB
or something along those lines, because although this change allows
coding smaller transforms for bigger predictors, it increases the
overhead of coding EOBs to skip the parts where the residual is
near-zero, and thus the overall gain is not as high as we'd expect.
Change-Id: I552ce1286487267f504e3090b683e15515791efa
there are still a couple type of warning left, which are related to
double constants assigned to float type. As those would be addressed
by the conversion of transforms into integer version. This commit
has left those un-dealt with.
Change-Id: I48fd9b489c0c27ad6b543f4177423419f929f2bb
