histogram_symbols is converted to uint32_t and <<8 into
histogram_argb.
Using a uint32_t buffer from the start prevents copying and
converting the data.
Change-Id: I245003a6a0f048c31519afa25a600d4479e762e3
In practice, this can never happen because:
- 'streak' is at most as long as a histogram
- 'count' counts the number of streaks
'streak' and 'count' are therefore at most as big as the histogram
length which is at most the max of VP8LHistogramNumCodes,
which is 256+24+(1<<10).
Change-Id: I31c8834543479c8a9260732313ea26b045519515
The histograms count the occurrences of len/dist in entropy images.
Those (at most (1<<14) by (1<<14)) are sub-sampled by at least
MIN_HUFFMAN_BITS == 2, hence at most 24 bits in a histogram value.
At most, we multiply by 19 (because the longest histogram is of
size 40 and we do 40>>1, cf code) for the bit cost. So it all fits
in 32 bits.
Change-Id: Ife24b035f54794851ff31f2fac07901f724c6d7f
1 space is most common in the source; this fixes some mixed cases within
lossless files, likely from clang-format
Change-Id: I504206d5bf418781d4131ee73570ecee4e0a69a1
A WebPPicture instance is necessary to call WebPReportProgress() which
sets WebPPicture::error_code so as well use WebPEncodingSetError() to
record errors too, instead of functions returning a WebPEncodingError.
However there must be one WebPPicture instance per thread, with error
codes merged at sync time. A mutex could simplify that but it is not
the objective of this change.
https://groups.google.com/a/webmproject.org/g/webp-discuss/c/yOiP8APubgc/m/vCTvxl6ODgAJ
Change-Id: Ia1a8f9d1199202e1c88484ce719b0180a80447ce
Fix another pessimization found by the pingo image compressor.
Refactoring is necessary to make LZ77 computation
common to cache or no-cache analysis.
Slower by 1.7x instead of 2x
Change-Id: I396701ea6e88543dbfe9471eb552877f6c8ce1e3
previously if the mappings allocation failed histo_queue->queue would be
uninitialized; split the conditionals
Change-Id: I1b50b987e734393893dc8a83a3f314522ccd0c83
The old code simply did not make sense.
The effect is that the pair would be popped from the
queue no matter what; as the queue is small, it does
not matter that much on the results.
But it will matter for a later CL.
Change-Id: If50c9fa9d7f3ac3c48bb7336d81479287d4944c4
When histograms are empty, it is easy to add them.
They should also not be considered when merging histograms
(it is a waste of CPU).
This does not change the compression performance,
just the speed.
Change-Id: I42c721ca0f9c5ea067e73b792aa3db6d5e71d01f
As backward references use the plane code when checking the cost
of a distance, statistics used to compute the cost should use it too.
This provides a small compression improvement at no speed cost.
Change-Id: Icade150929ee39ef6dc0d8b1fc85973086ecf41d
Between each iteration we keep track of the previously found
potential merge hence less work to do.
Change-Id: I2b6237447e79443516a6111727d96c24f10bd98a
It was a bad implementation of a Lehmer random number generator
(the saturation was done wrong and mostly & was used instead of % .....).
That lead to "for" loop stuck with the same values given a specific seed,
hence wasted "for" loops (e.g. seed getting at 374988608 and modulo of 64
later leads to 0 even when updating the seed with the old formula).
As the "for" loops now always return a proper pair of histograms, their
number can greatly be reduced, hence a speedup.
Change-Id: I9f5b44d66cc96fd4824189d92276c3756c8ead5b
Previously, the stochastic method for histogram
combination could finish in a greedy way
if the number of iterations to perform so was smaller.
Except that another greedy combination was performed
afterwards ... hence wasted CPU in some cases.
Change-Id: Ic0f26873e6dc746679486b91cb35d73efee91931
this avoids duplicates between these trees and dsp/, e.g., enc/tree.c,
dec/tree.c, making pulling the whole library source tree into one target
possible
BUG=webp:279
Change-Id: I060a614833c7c24ddd37bf641702ae6a5eef1775
