Profiled data: Profiled few images and found that in the function VP8LFastLog,
90% of time table lookup is performed, while rest of time (10%) call to log
function is made. Typical lookup accounts for 10 CPU instructions and call to
log 200 instruction counts. The weighted average comes out to be 30
instructions per call. For mid qualities (25-75), this function (VP8LFastLog)
accounts for 30-50% of total CPU cycles (via call path: VP8LCOlorSpaceTransform
-> PredictionCostCrossColor -> ShannonEntropy). After this change, the log is
called less that 1% of time, with average instructions being 15 per call.
Measured the performance over 1000 files for various qualities and found
overall compression speedup between 10-15% (in quality range [0, 75]). The
compression density loss is around 0.5% (though at some qualities, compression
is little better as well).
Change-Id: I247bc6a8d4351819c871f19d65455dc23aea8650
make elements of "Multiplier" struct unsigned, so that any negative values are
automatically converted to "mod 256" values.
Change-Id: Iab4f9bacc50dcd94a557944727d9338dbb0982f7
so that it uses original values of left, top etc for prediction rather than the
predicted values of the same. Also, do some renaming in the same to make it
more readable.
Change-Id: I2fe94e35a6700bd437f5c601e2af12323bf32445
- VP8LEncAnalyze, EvalAndApplySubtractGreen, ApplyPredictFilter,
ApplyCrossColorFilter
- Added palette handling and transform buffer management in VP8LEncodeImage()
- Add Transforms (subtract Green, Predict, cross_color) to dsp/lossless.c.
These are more-or-less copied from src/lossless code.
After this Change, will implement the EncodeImageInternal() method.
Change-Id: Idf71f803c24b3b5ae3b5079b15e019721784611d
src/dsp/lossless.c: In function 'VP8LInverseTransform':
src/dsp/lossless.c:312:23: warning: 'packed_pixels' may be used
uninitialized in this function [-Wuninitialized]
src/dsp/lossless.c:304:16: note: 'packed_pixels' was declared here
src/dsp/lossless.c:258:34: warning: 'm.red_to_blue_' may be used
uninitialized in this function [-Wuninitialized]
src/dsp/lossless.c:275:17: note: 'm.red_to_blue_' was declared here
src/dsp/lossless.c:257:34: warning: 'm.green_to_blue_' may be used
uninitialized in this function [-Wuninitialized]
src/dsp/lossless.c:275:17: note: 'm.green_to_blue_' was declared here
src/dsp/lossless.c:255:33: warning: 'm.green_to_red_' may be used
uninitialized in this function [-Wuninitialized]
src/dsp/lossless.c:275:17: note: 'm.green_to_red_' was declared here
patch by pepijn vaneeckhoudt
Change-Id: Iffa4764487a75479df45e772169325cd9ee60d94
Pulled from the current HEAD (218c32e).
The history of this and related files is a bit entangled so rather
trying to split the changes and introduce some noise in master's history
we'll start with a fresh snapshot.
The file progression is still available in the experimental branch.
Change-Id: I40538799dbf999abb9408ac83f55b897d8e22498
