This is required for WebP lossy+Alpha images, where Alpha channel is taking
60-70% of the compression (CPU) cycles.
Also evaluated on 1000 PNG corpus and overall compression speed
is 15-40% better for lossy (PNG+Alpha) compression.
The pure lossless compression numbers are almost same (or little
better) with this change.
Change-Id: I9e5ae7372ed6227a9a5b64cd9cff84c747195a57
- Changed the dynamic range where more aggressive
(BackwardReferencesTraceBackward) heuristic is run from quality > 10
(instead of quality > 25).
- Limit the backward-ref Window size to 16*width & 256*width for lower
qualities ([0, 25[ & [25, 50[) respectively, instead of 1M window.
- Evaluate the params for HashChainFindCopy outside this function call
and pass it, instead of recomputing them for every call.
Change-Id: If9eedfc14b978e7632d7cf69c96186e2910b0554
in debug mode, some float operations see their intermediate
values stored in memory rather than staying in the FPU (which
is 80bit precision).
Several fixes are possible (breaking long calculations into
atomic steps for instance), but simpler of all is just about
turning the cost[] array into float* instead of double*.
The code is a tad faster, and i didn't see any major output
size difference.
Change-Id: Icf1f833e15f8ee4ecc7f9a521d07fdc96ef711aa
Order-by-cost mostly unchanged (up to a scaling constant 1/log(2))
(except for few minor diff in < 2% of cases)
+ remove unused field cost_mode->cache_bits_
Change-Id: I714f8ab12f49a23f5d499a64c741382c9b489a3e
* ~1-4% faster
* if it's not used, don't use it
* remove the special handling of cache_bits = 0
* remove some tests in the loops
Change-Id: I19d87c3ca731052ff532ea8b2d8e89816507b75f
Fix inequality assertion on number of palette colors.
Fix inequality assertion test in BackwardReferencesHashChainFollowChosenPath.
Change-Id: Ie3242f1bbeaf96db91b839b6732ccce2634cebf3
Updated histo_bits to 3 from 4 and changed the quality threshold for inner loop for HashChainFindCopy.
Impact: 0.5%-0.8% better bpp with 15%-20% hit on encoding throughput
at default encoding settings.
Change-Id: I316ef88403148b1e19036fa0817d944eb0301255
CostModelBuild() and TrackBackwards() returns weren't checked
+ code clean-up
+ de-inline VP8LBackwardRefs non-critical methods
+ shuffle the .h around to group things together
+ extract some constants as #define's
+ fixed the "if (!(cc_init = ...)) {...}" constructs
+ removed some unneeded VP8L prefixes
Change-Id: Ic634cb87bc6b2033242d3e8e8731fab4c134f327
The new method VP8LGetBackwardReferences hides internal
heuristics used for choosing RLE or LZ77 based refs.
- Tuned VP8LHashChainFindCopy for better compression at higher Q.
- Refactored code.
- Removed the unused method VP8LVerifyBackwardReferences.
Change-Id: Ibb7bb072bab5a49a001577a20d88226f52e6c663
* de-inline some function
* make VP8LBackwardRefs be more like a vectorwith max capacity
* add bit_cost_ field to VP8LHistogram
* general code simplifications
* remove some memmov() from HistogramRefine
* simplify HistogramDistance()
...
Change-Id: I16904d9fa2380e1cf4a3fdddf56ed1fcadfa25dc
