Return key/index if the query is found, and -1 otherwise.
The benefit of this is to save a hashing computation.
Change-Id: Iff056be330f5fb8204011259ac814f7677dd40fe
reserve src/ for the code of the main libraries: libwebp, libwebpdemux
and libwebpmux
+ demote this library to internal only; i.e., don't install the header +
lib with make install
Change-Id: I8c9844db8f494be0fa0a2549a5b75b5cebcf666d
We add the following MSA optimized rescaling functions:
- RescalerExportRowExpand
- RescalerExportRowShrink
Change-Id: Ic1c76065423b02617db94cf0c22bb564219b36e6
We add the following MSA optimized color transform functions:
- TransformColor
- SubtractGreenFromBlueAndRed
Change-Id: Ib182d2b5faa7191f503ce70f0dfde0ac89402fd3
This improves compression by ~5% at default quality.
If only 'allow_mixed' is on (but 'minimize_size' isn't), we continue to
use a heuristic to try one of the two or both.
Change-Id: Ia573a73ea26ad25f9debff759eed69d2b0449e82
The decision is based on the variance between DC values of each
sub-4x4 block. This heuristic is rather ok for predicting whether
the 2nd transform (intra-16) is going to help or not.
The decision threshold varies with quality (=quantization).
It's only used for -m 0 and -m 1, where no full RD-opt is performed.
It actually makes these modes quite faster, with RD curve much
closer to the -m 2 mode.
Change-Id: I15f972db97ba4082cbd1dfd16bee3eb2eca701a8
We add the following MSA optimized encoder quantization functions:
- QuantizeBlock
- Quantize2Blocks
Change-Id: Ie32b442afa99eee62d2ef48942b41116a4e157d3
pre-allocating a sorted[] array for most common cases of small
alphabet size cuts a lot of traffic.
Change-Id: I73ff2f6e507f81b0b0bb7d9801a344aa4bcb038a
+ s/src_a/dst_a/
+ remove unnecessary (void) as expected_num_lines_out is used within the
function
Change-Id: Ic45f798ef22bd19eaabf1a0512d1cf8a201bb4b5
- 6/14/2016: version 0.5.1
This is a binary compatible release.
* miscellaneous bug fixes (issues #280, #289)
* reverted alpha plane encoding with color cache for compatibility with
libwebp 0.4.0->0.4.3 (issues #291, #298)
* lossless encoding performance improvements
* memory reduction in both lossless encoding and decoding
* force mux output to be in the extended format (VP8X) when undefined chunks
are present (issue #294)
* gradle, cmake build support
* workaround for compiler bug causing 64-bit decode failures on android
devices using clang-3.8 in the r11c NDK
* various WebPAnimEncoder improvements
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Merge tag 'v0.5.1'
libwebp-0.5.1
- 6/14/2016: version 0.5.1
This is a binary compatible release.
* miscellaneous bug fixes (issues #280, #289)
* reverted alpha plane encoding with color cache for compatibility with
libwebp 0.4.0->0.4.3 (issues #291, #298)
* lossless encoding performance improvements
* memory reduction in both lossless encoding and decoding
* force mux output to be in the extended format (VP8X) when undefined chunks
are present (issue #294)
* gradle, cmake build support
* workaround for compiler bug causing 64-bit decode failures on android
devices using clang-3.8 in the r11c NDK
* various WebPAnimEncoder improvements
* tag 'v0.5.1': (30 commits)
update ChangeLog
Clarify the expected 'config' lifespan in WebPIDecode()
update ChangeLog
Fix corner case in CostManagerInit.
gif2webp: normalize the number of .'s in the help message
vwebp: normalize the number of .'s in the help message
cwebp: normalize the number of .'s in the help message
fix rescaling bug: alpha plane wasn't filled with 0xff
Improve lossless compression.
'our bug tracker' -> 'the bug tracker'
normalize the number of .'s in the help message
pngdec,ReadFunc: throw an error on invalid read
decode.h,WebPGetInfo: normalize function comment
Inline GetResidual for speed.
Speed-up uniform-region processing.
free -> WebPSafeFree()
DecodeImageData(): change the incorrect assert
Fix a boundary case in BackwardReferencesHashChainDistanceOnly.
Make sure to consider small distances in LZ77.
add some asserts to delimit the perimeter of CostManager's operation
...
Change-Id: I44cee79fddd43527062ea9d83be67da42484ebfc
We add the following MSA optimized color transform functions:
- AddGreenToBlueAndRed
- TransformColorInverse
Change-Id: Iceab3813905955aa8b811253df9188512fc7de3f
(in case no alpha was present in the source .webp,
but user requested some)
Change-Id: I9011d38237907c60d6796a86bd2c72166aa80f27
(cherry picked from commit 06a38c7b1c)
This is essentially a revert of a3611513d2
and cfbcc5ece0.
Here is what happened: there was a corruption bug that eventually
got fixed by 0174d18d8b.
But before finding the root, a3611513d2
and cfbcc5ece0 hid the bug
by not imposing length of 1 when it was actually 2 or 3 (which does help
compression as a litteral is more efficient than an offset and a length
of size 2 or 3).
Change-Id: I6f18fc1f583a51ac9d8aab2508458264047cd493
We only perform a single pass, and swap the final histograms
into the beginning of the array as we go. Therefore, they are
already at the correct place at the end of the pass.
-> HistogramCompactBins() is removed, we just truncate the array.
output is bitwise the same.
Change-Id: I9508c96dda0f8903c927a71b06af4e6490c3249c
output should bit-write the same as before, in both
low_effort and non low_effort modes.
if anything, speed is a tad faster, probably because of the
reduced memory traffic.
Change-Id: Iaa2ddcfda2aaffefe7e5b7bc89216373d1ddb194
MAX_COLOR_COUNT was just a synonym and its use in the header was a bit
strange given the visibility of that define.
Change-Id: I536964ddc14a0c48263191b6afb80695b5a038e6
this function can be called not to decode pixels, but simply
to finish processing (through process_func()) the already decoded
pixels.
Change-Id: I80485e92e3c47f0aa3389476dcb82745a243fc4a
The optimization for (len != MIN_LENGTH) actually only holds for
(len > MIN_LENGTH) but (len < MIN_LENGTH) can now happen as len can
be changed in the loop before.
Change-Id: I3f9f91a540206c80385c5fba96c3d64ab9536752
On the non-fast path (use_8b_decode_=0) for decoding the alpha-mask,
we could end up requesting ApplyInverseTransform() with more rows
to process than NUM_ARGB_CACHE_ROWS. This could only happen on the
very last bottom rows of the image.
* ProcessRows() doesn't need to be fixed, since we never request more
than NUM_ARGB_CACHE_ROWS rows. Added an assert for that.
* the use_8b_decode_=1 case doesn't use argb_cache_, but rather does
the palette-decoding call directly. So, no problem here too.
Only the generic (and rather rare) case of calling ExtractAlphaRows()
was affected.
Change-Id: I58e28d590dcc08c24d237429b79614abcef1db7c
This is getting back to the old behavior which is actually better for
compression and speed with the latest patches.
Change-Id: I35884bab02589297c25d6e1e66dc5f13e05f7aa7
This was defined (slightly differently) at two places. Created a common
method and moved to utils/utils.[hc].
Change-Id: I66c3ac6dea24e0cd2c0eaa5440f3142b4dbbe23b
we don't need to store the resulting histogram, so no need to
call HistogramAddEval().
Allows some signature simplifications...
Change-Id: I3fff6c45f4a7c6179499c6078ff159df4ca0ac53
In case where the same offset is found in consecutive pixels,
the cost computation from one pixel can be re-used for the next.
Change-Id: Ic03c7d4ab95f3612eafc703349cfefd75273c3d7
and also recycle the malloc'd intervals
This avoids quite some malloc/free cycles during interval managment.
Change-Id: Ic2892e7c0260d0fca0e455d4728f261fb4c3800e
In a lot of cases, only one interval is used. This can cause
a lot of malloc/free cycles for only 56 bytes. By caching this
single interval and re-using it, we remove this cycle in most
frequent cases.
Change-Id: Ia22d583f60ae438c216612062316b20ecb34f029
As per the spec
(https://developers.google.com/speed/webp/docs/riff_container), only the
extended file format can contain an unknown chunk. So, when assembling a
WebP file with muxer, whenever there is an unknown chunk present, we
should create a VP8X chunk (even though none of the features are
present).
BUG=webp:294
Change-Id: I5da52d311e1853d40063d0f5026100d4325effaa
In some cases, the hash chain for a function is filled several
times:
- GetBackwardReferences -> CalculateBestCacheSize ->
BackwardReferencesLz77 that computes the hash chain
- GetBackwardReferences ->
(not always) BackwardReferencesTraceBackwards ->
BackwardReferencesHashChainDistanceOnly that computes the hash
chain in a slightly different way
Speed and compression performance are slightly changed (+ or -)
but will be homogneized in a later patch.
Change-Id: I43f0ecc7a9312c2ed6cdba1c0fabc6c5ad91c953
This reverts commit 169004b1d5.
this changes the ABI, so should bump versions and add a note to NEWS
when we're ready to expose it
Change-Id: Ic5bbd0aee2b6fd0f9d438a9effedf22fe0cec4bf
tl;dr
We do the following:
- Start with transparent value of 0x00000000 instead of 0x00ffffff, so that
WebPCleanupTransparentAreaLossless() is a no-op.
- Restore the original canvas after lossy encoding, to discard changes made by
WebPCleanupTransparentArea() before the next encode.
Explanation of why:
In the mixed mode, anim_encoder tries to encode using both lossless and lossy
compression. In fact, when "min_size" option is enabled, there are at most 4
encodes that can happen in this order:
- lossless with dispose none
- lossy with dispose none
- lossless with dispose background
- lossy with dispose background
But both lossless and lossy both potentially modify the canvas during encode
(for better compression):
- Lossless: WebPCleanupTransparentAreaLossless() turns all transparent pixels
to 0x00000000
- Lossy: WebPCleanupTransparentArea() flattens some transparent pixels
So, the result is that, sometimes we feed the modified canvas to the encoder
instead of the original one, which isn't the right thing to do.
This also applies to just lossless or just lossy encoding, as multiple encodes
happen (with the two dispose methods) in those cases too.
Change-Id: Idfa8ce831a1627014785ba7d0316c42f72594455
This was defined (slightly differently) at two places. Created a common
method and moved to utils/utils.[hc].
Change-Id: I19adc9c48f2a4e2ec9d995e78add6f25172774c2
no longer gate this on WEBP_FORCE_ALIGNED as WebPMemToUint32() provides
this service. replace that check with WORDS_BIGENDIAN as the block is
currently little-endian specific.
Change-Id: Ie04ec0179022d20dab53da878008ae049837782f
the read size may be fixed, but the offsets into buf_ are not. forcing
an aligned read then shifting or using a temporary would be costly. this
is less important now that WebPMemToUint32() is being used.
Change-Id: I357fec8f750969cce91987abebed2f95e27a835f
Instead of comparing all the following pixels over len (which can
frequently reach the maximum MAX_LENGTH=4096 for some images),
intervals are stored and compared.
Change-Id: I0dafef6cc988dde3c1c03ae07305ac48901d60ee
The old implementation in enc/near_lossless.c performing a separate
preprocessing step is used only when a prediction filter is not used,
otherwise a new implementation integrated into lossless_enc.c is used.
It retains the same logic for converting near lossless quality into max
number of bits dropped, and for adjusting the number of bits based on
the smoothness of the image at a given pixel. As before, borders are not
changed.
Then, instead of quantizing raw component values, the residual after
subtract green and after prediction is quantized according to the
resulting number of bits, taking care to not cross the boundary between
255 and 0 after decoding. Ties are resolved by moving closer to the
prediction instead of by bankers’ rounding.
This results in about 15% size decrease for the same quality.
Change-Id: If3e9c388158c2e3e75ef88876703f40b932f671f
copy and paste error in the previous commit, change
no_sanitize("unsigned-integer-overflow") from WEBP_UBSAN_IGNORE_UNDEF ->
WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW
Change-Id: Id178ee14df1f2c4923a91ce423241e26b60b5d32
add WEBP_UBSAN_IGNORE_UNDEF to WebPMemToUint32() / WebPUint32ToMem()
when WEBP_FORCE_ALIGNED is unset
Change-Id: I726b2e708ce29681584eb10c8874d5cf1e798756
include utils.h directly where needed to allow utils.h to rely on
defines from dsp.h in a follow-up.
Change-Id: I32e26aaeb0b04ba60b3332f685f9a2be5a0a8d3d
configure gets 2 new options:
--enable-neon / --enable-neon-rtcd
the NEON modules are split to their own convenience lib and built with
auto-detected flags if none are given via CFLAGS.
the /proc/cpuinfo check will only be used for armv7 targets whose
toolchain does not enable NEON by default or didn't have NEON forced by
the CFLAGS from the environment.
Change-Id: I2755bc1d065d5d6ee6143b44978c2082f8bef1c5
This fixes decoders built against clang-3.8 (r11c). Without this change
bad conditional code would be generated causing all calls to
WebPParseHeaders() to return 4 (UNSUPPORTED_FEATURE).
Original fix:
https://android-review.googlesource.com/#/c/196123
Change-Id: Id4b4d84048d347cea110b6cf297ef9ef4fbed323
the number of segments are previously validated, but an explicit check
is needed to avoid a warning under gcc-4.9
this is similar to the changes made in:
c8a87bb AssignSegments: quiet -Warray-bounds warning
3e7f34a AssignSegments: quiet array-bounds warning
Change-Id: Iec7d470be424390c66f769a19576021d0cd9a2fd
This will allow to work in-place on cropped area later.
Also sped up the inverse gradient filtering in SSE2 (~4%)
Change-Id: I463149eee95d36984328f163a1e17f8cabd87441
This is only possible if the filtering is not VERTICAL or GRADIENT.
Otherwise, we need the spatial predictors and hence need the un-visible
part above crop_top row.
COLOR_INDEX transform is the only transform that is not predicted
from previous row. Applying the same for other transform (spatial
predict, ...) is going to be more involve and use an extra temporary row.
+ remove ApplyInverseTransformsAlpha()
(work is done directly within ExtractPalettedAlphaRows())
+ change back to using filter_ instead of unfilter_func_
Change-Id: I09e57efae4a4af00bde35f21ca6e3d73b35d7d43
not exactly same.
Based on lossy WebP quality setting, ignore minor differences when
flattening
similar blocks.
For 6k set, at default quality with '-min_size' option, improves
compression by 0.3%
Change-Id: Ifcb64219f941e869eb2643e231220b278aad4cd4
there's some subtle changes:
- DecodeAlphaData() may be called with pos==end because we don't want
to decode more data (there's none left), but because we want to apply
process_func() to all the unprocessed pixels already decoded
- last_row is exclusive and should be understood as 'up to last_row'. Can be misleading.
- VP8LDecodeAlphaImageStream() was testing dec->last_pixel_ for completion,
which was wrong because last_pixel_ is the last *decoded* pixel, not the
last *processed* one. -> test now uses last_row_, as expected
Change-Id: I1fb04ba25cd7a4775db9e3deee3e2ae80f9c0a75
this might change some crc slightly, since WebPDequantizeLevels()
performs an analysis pass, counting levels, which impacts the smoothing.
Now, the cropping area is not the same, so minor diffs are expected here
and there.
Change-Id: I3cce1e40c6f11c25b7c841044d637685c5740352
* make ALPHNew/Delete static
* properly init ALPHDec::io_
* introduce AllocateAlphaPlane() and WebPDeallocateAlphaMemory()
* reorganize VP8DecompressAlphaRows()
but we're still allocate the full alpha-plane. Optim will come
in another patch since it's tricky
Change-Id: Ib6f190a40abb7926a71535b0ed67c39d0974e06a
this change will be superseded by patch #335160 eventually, but until then
let's fix the problem temporarily.
Change-Id: Iafd979c2ff6801e3f1de4614870ca854a4747b04
When FlattenSimilarBlocks() was making some blocks transparent with
averaged RGB values, filtering in lossy compression was causing
blockiness just outside the edge of these blocks.
Disabling filtering for that particular case avoid these block
artifacts.
The total encoded size of the 6k GIF set remains roughly the same (in
fact, reduces a bit).
Change-Id: Ida71cbabd59d851e16d871f53d19473312b3cc77
We pick a mapping with quality 0 mapping to max diff 32, to quality 100
mapping to max_diff 1.
For 6k GIF image set, this improves compression by:
4% at quality 0
0.05% at quality 75
Benefits the MovingThumbnailer test videos too.
Change-Id: I6838ce864d41e1e65311d26b9b8115a12390a253
This way we can ignore some noisy pixels and get tighter frame
rectangles.
Some results:
- Correctness:
Tested that anim_diff reports all images are identical for lossless, and
similar min_psnr value for lossy and mixed modes.
Also checked output images visually to make sure there weren't any
obvious kinks.
- Compression:
A very tiny improvement for 6000 image GIF set we have (0.03%) for lossy
and mixed mode. For some of these images, frames get dropped
automatically as they have a very small diff from previous frame.
10 images from test_video_frames_png show a clear improvement in
compression though. This CL leads to 7 out of 9 lossy WebPs getting
smaller -- for one of them, this leads to a higher quality being picked
(as that’s still < 150 KB).
Change-Id: If539b9e77e1375aa15edc8f926933593a9865f1c
and also pass 'VP8Io* io' extra param to VP8DecompressAlphaRows()
This is somehow in preparation for some memory optimizations in
the 'cropping' case. For now, only the easy crop_bottom case is
optimized.
Change-Id: Ib54531ba057bf62b98422dbb6c181dda626c72c2
This avoids generating file that would trigger a decoding bug
found in 0.4.0 -> 0.4.3 libwebp versions.
This reverts commit 6ecd72f845.
Change-Id: I4667cc8f7b851ba44479e3fe2b9d844b2c56fcf4
The mode's bits were not taken into account, which is ok for most of cases.
But in case of super large image, with 'easy' content, their overhead starts
mattering a lot and we were omitting to optimize for these.
Now, these mode bits have their own lambda values associated, limiting
the jerkiness. We also limit (for -m 2 only) the individual number of bits
to something that will prevent the partition 0 overflow.
removed the I4_PENALTY constant, which was a rather crude approximation.
Replaced by some q-dependent expression.
fixes issue #289
Change-Id: I956ae2d2308c339adc4706d52722f0bb61ccf18c
If value is '2', it means the buffer is a 'slow' one, like GPU-mapped memory.
This change is backward compatible (setting is_external_memory to 2
will be a no-op in previous libraries)
dwebp: add flags to force a particular colorspace format
new flags is:
-pixel_format {RGB,RGBA,BGR,BGRA,ARGB,RGBA_4444,RGB_565,
rgbA,bgrA,Argb,rgbA_4444,YUV,YUVA}
and also,external_memory {0,1,2}
These flags are mostly for debuggging purpose, and hence are not documented.
Change-Id: Iac88ce1e10b35163dd7af57f9660f062f5d8ed5e
This is in preparation for some SSE2 code.
And generally speaking, the whole SSIM code needs some
revamp: we're not averaging the SSIM value at each pixels
but just computing the overall SSIM value once, for the whole
plane. The former might be better than the latter.
Change-Id: I935784a917f84a18ef08dc5ec9a7b528abea46a5
based on the sse2 change in:
9960c31 Remove an unnecessary transposition in TTransform.
~9-10.5% faster at the function-level, < 1% overall
Change-Id: I44413369b230b250fb0dbc51ff2f17cfeda609b7
- The result is now indeed closest among possible results for all inputs, which
was not the case for bits>4, where the mapping was not even monotonic because
GetValAndDistance was correct only if the significant part of initial fit in
a byte at most twice.
- The set of results for a larger number of bits dropped is a subset of values
for a smaller number of bits dropped. This implies that subsequent
discretizations for a smaller number of bits dropped do not change already
discretized pixels, which improves the quality (changes do not accumulate)
and compression density (values tend to repeat more often).
- Errors are more fairly distributed between upwards and downwards thanks to
bankers’ rounding, which avoids images getting darker or lighter in overall.
- Deltas between discretized values are more repetitive. This improves
compression density if delta encoding is used.
Also, the implementation is much shorter now.
Change-Id: I0a98e7d5255e91a7b9c193a156cf5405d9701f16
Pass them along to internal 'pic' object, so that progress can be reported back
and user data can also be inspected.
Change-Id: Idb5d0d4a76d07283d704a86c5892e1ad7bda09fa
SSE4.1 is slower than the SSE2 implementation and this seems to
be due to a slow _mm_loadl_epi64 implementation by gcc
(hence a bug with my gcc 4.8) and a very slow _mm_hadd_epi32. Both
got confirmed by IACA and experiments.
Change-Id: I05607f66b7ccd8f4f42e000693aea583ffd5768f
We were not updating the current_width_, which is usually
not a problem, unless we use Delta Palette with small number
of colors
-> Addressed this re-entrancy problem by checking we have
enough capacity for transform buffer.
The problem is not currently visible, until we restrict
the number of gradient used in delta-palette to less than 16.
Then the buffers have different current_width_ and the problem
surfaces.
Change-Id: Icd84b919905d7789014bb6668bfb6813c93fb36e
The transpose refactoring will help removing a transpose in a
later CL.
The horizontal add function helps removing a _mm_sad_epu8 in DC8uv
=> the latency/throughput went from 29/25 to 23/19
Change-Id: I5f3dfd4aad614eb079b1e83631e6a7cef49a3766
'implicit conversion from 'int' to 'short' changes value from 33050 to
-32486'
original patch:
https://codereview.chromium.org/1657313003/
Make libwebp build with -Wconstant-conversion from newer clangs.
After http://llvm.org/viewvc/llvm-project?rev=259271&view=rev, clang
points out that _mm_set1_epi16(33050) causes an overflow in the short
argument to _mm_set1_epi16(). Since there's no version that takes an
unsigned short, add an explicit cast to tell the compiler that this is
intentional.
No behavior change.
Change-Id: I6b4e3401b15cfbcc895f9e81b5c2dc59d43ffb9b
The code and logic is unified when computing bit entropy + Huffman cost.
Speed-wise, we gain 8% for lossless encoding.
Logic-wise, the beginning/end of the distributions are handled properly
and the compression ratio does not change much.
Change-Id: Ifa91d7d3e667c9a9a421faec4e845ecb6479a633
setting all transparent pixels to black rather than the "flatten" method.
0.3% smaller filesize on the 1000 PNGs if alpha cleanup is used (before: 18685774, after: 18622472)
Change-Id: Ib0db9e7ccde55b36e82de07855f2dbb630fe62b1
The functions containing magic constants are moved out of ./dsp .
VP8LPopulationCost got put back in ./enc
VP8LGetCombinedEntropy is now unrefined (refinement happening in ./enc)
VP8LBitsEntropy is now unrefined (refinement happening in ./enc)
VP8LHistogramEstimateBits got put back in ./enc
VP8LHistogramEstimateBitsBulk got deleted.
Change-Id: I09c4101eebbc6f174403157026fe4a23a5316beb
This implementation brings:
- an SSE implementation of packing / unpacking
- bigger buffers processed at the same time
The speedup is of 4% on lossy decoding (YUV to RGB), 0.5% on
lossy encoding (RGB to YUV was already optimized).
Change-Id: Iec677ee17f91c08614d1adab67c6df551925767f
* changes:
demux: remove GetFragment()
demux: remove dead fragment related TODO
demux, Frame: remove is_fragment_ field
demux,WebPIterator: remove fragment_num/num_fragments
demux: remove WebPDemuxSelectFragment
this hasn't been set since parsing of the experimental chunk was
removed.
+ cleanup IsValidExtendedFormat(). is_fragmented has caused immediate
failure since:
4e2589f demux: restore strict fragment flag check
Change-Id: If9ecfc19556297100a6d5de1ba2cffdcbdc6c8fd
INFO: From Compiling src/dsp/cpu.c:
src/dsp/cpu.c: In function 'x86CPUInfo':
src/dsp/cpu.c:36:3: inconsistent operand constraints in an 'asm'
With PIC and mcmodel=medium, the %rbx register must be saved and
restored which causes this problem. This was also solved in GCC-4.9 with
this patch:
https://gcc.gnu.org/ml/gcc-patches/2012-12/msg01484.html
Tested:
Builds fine with this change.
Change-Id: Icca8eea7bf5af3ef9f17f6ae2886e3430143febf
CombinedShannonEntropy takes 30% for lossless compression.
This implementation speeds up the overall process by 2 to 3 %.
Change-Id: I04a71743284c38814fd0726034d51a02b1b6ba8f
The previous priority system used a heap which was too heavy to
maintain (what was gained from insertions / deletions was lost
due to a linear that still happened on the heap for invalidation).
The new structure is a priority queue where only the head is
ordered.
Change-Id: Id13f8694885a934fe2b2f115f8f84ada061b9016
SimpleQuantize()
it's now a single function, that reconstructs the intra4x4 block during the scan
The I4_PENALTY had to be adjusted.
Overall, result is better quality-wise (esp. at q < 50), and a tad faster too.
method #0, #1 and #3+ are unchanged
Change-Id: If262aeb552397860b3dd532df8df6b1357779222
* Precision is slightly different
* also implemented in SSE2 the missing WebPUpsamplers for MODE_ARGB, MODE_Argb, MODE_RGB565, etc.
* removing yuv_tables_sse2.h saved ~8k of binary size
* the mips32/mips_dsp_r2 code is disabled for now, since it has drifted away
* the NEON code is somewhat tricky
Change-Id: Icf205faa62cf46c2825d79f3af6725dc1ec7f052
Gives 0.9% smaller (2.4% compared to before alpha cleanup) size on the 1000 PNGs dataset:
Alpha cleanup before: 18856614
Alpha cleanup after: 18685802
For reference, with no alpha cleanup: 19159992
Note: WebPCleanupTransparentArea is still also called in WebPEncode. This cleanup still helps
preprocessing in the encoder, and the cases when the prediction transform is not used.
Change-Id: I63e69f48af6ddeb9804e2e603c59dde2718c6c28
The 32-bit buffers are actually rarely 64-bit aligned.
The new solution uses memcmp and is alignment agnostic.
It is also slightly faster.
Change-Id: I863003e9ee4ee8a3eed25b7b2478cb82a0ddbb20
for more speed.
This gives a roughly a 1% speedup for low_effort. But actually this is a
preparation for the upcoming CL that changes RGB values of transparent pixels
based on prediction, which should not be done for low_effort because that would
slightly hurt its performance.
On 1000 PNGs, with quality 0, method 0:
Before:
Compression (output/input): 2.9120/3.2667 bpp, Encode rate (raw data): 36.034 MP/s
After:
Compression (output/input): 2.9120/3.2667 bpp, Encode rate (raw data): 36.428 MP/s
Change-Id: I5ed9f599bbf908a917723f3c780551ceb7fd724d
Arrays were compared 32 bits at a time, it is now done 64 bits at a time.
Overall encoding speed-up is only of 0.2% on @skal's small PNG corpus.
It is of 3% on my initial 1.3 Mp desktop screenshot image.
Change-Id: I1acb32b437397a7bf3dcffbecbcd4b06d29c05e1
The same computation was done for both values: go over two buffers,
sum them up, and take a decision on the sum at each iteration.
MIPS32 code has been disabled for now, pending a code update.
Change-Id: I997984326f7092b3dbb8cfa1e524bd8132b2ab9d
instead of per block. This prepares for a next CL that can make the
predictors alter RGB value behind transparent pixels for denser
encoding. Some predictors depend on the top-right pixel, and it must
have been already processed to know its new RGB value, so requires per
scanline instead of per block.
Running the encode speed test on 1000 PNGs 10 times with default
settings:
Before:
Compression (output/input): 2.3745/3.2667 bpp, Encode rate (raw data): 1.497 MP/s
After:
Compression (output/input): 2.3745/3.2667 bpp, Encode rate (raw data): 1.501 MP/s
Same but with quality 0, method 0 and 30 iterations:
Before:
Compression (output/input): 2.9120/3.2667 bpp, Encode rate (raw data): 36.379 MP/s
After:
Compression (output/input): 2.9120/3.2667 bpp, Encode rate (raw data): 36.462 MP/s
No effect on compressed size, this produces exactly same files. No
significant measured effect on speed. Expected faster speed from better
memory layout with scanline processing but slower speed due to needing
to get predictor mode per pixel, may compensate each other.
Change-Id: I40f766f1c1c19f87b62c1e2a1c4cd7627a2c3334
the problem was the incorporation of the extra constant 1<<16 in the kC1
constant, to emulate the addition. It's now removed and the addition is
performed explicitly.
No real speed difference observed.
cf. issue #278
Change-Id: I2c6499031571d98afff392fb5ebe21a5fa60722d
* changes:
Makefile.vc: enable WEBP_USE_THREAD for windows phone
thread: use CreateThread for windows phone
thread: use WaitForSingleObjectEx if available
thread: use InitializeCriticalSectionEx if available
thread: use native windows cond var if available
if FANCY_UPSAMPLING was not defined but io->fancy_upsampling was set,
then the call to WebPInitSamplers() was skipped -> boom.
Change-Id: Id63e2ecc09f532fbe2ec9936d9ce4b502ba8fac5
Rename the flag to exact instead of the opposite cleanup_alpha. Add the flag to
WebPConfig. Do the cleanup in the webp encoder library rather than the cwebp
binary, this will be needed for the next stage: smarter alpha cleanup for
better compression which cannot be done as a preprocessing due to depending on
predictor choices in the encoder.
Change-Id: I2fbf57f918a35f2da6186ef0b5d85e5fd0020eef
the original change triggered several internal API modifs.
This is to ensure that we're never computing pointer that can
possibly wrap around, or differences between pointers that can
overflow.
no observed speed difference
Change-Id: I9c94dda38d94fecc010305e4ad12f13b8fda5380
We now consider 3 special cases:
* htree-group has only 1 code (no bit is read from bitstream)
* htree-group has few enough literal symbols, so that all the bit
codes can fit into a look-up table of less than 64 entries
* htree-group has a trivial arb literal (not GREEN!), like before
No overall speed change.
Change-Id: I6077fa0b7e5c31a6c67aa8aca859c22cc50ee254
We now get error string instead of printing it.
The verbose option is now only used to print info and warnings.
Change-Id: I985c5acd427a9d1973068e7b7a8af5dd0d6d2585
It was needed earlier for WebPAnimEncoder API when it was using structs
like WebPConfig, but it only uses pointers to those now.
Change-Id: Ic0c144966421c678e8ef54b3fa81574bb2c9cd08
global effect is ~2% faster encoding from JPG source
and ~8% faster lossless-webp source decoding to PGM (e.g.)
Also revamped the YUVA case to first accumulate R/G/B value into 16b
temporary buffer, and then doing the UV conversion.
-> New function: WebPConvertRGBA32ToUV
Change-Id: I1d7d0c4003aa02966ad33490ce0fcdc7925cf9f5
Just for RGB24/BGR24 for now, which are the hard-to-optimize ones.
SSE2 implementation coming next.
ConvertRowToY() should go into dsp/ too, at some point.
Change-Id: Ibc705ede5cbf674deefd0d9332cd82f618bc2425
also switch to using ExtractAlpha() instead of hard-coding the loop.
The ARGBToY/UV functions are rather easy to port to SSE2 / NEON.
Change-Id: I8f1346a9ca427a36ce2d6c848369ca7964d8b3c7
use 'u' rather than the unnecessary 'l' as a suffix. this prevents a
conversion warning with some toolchains
Change-Id: I21c33ce08819b3c839c75e03a8f7f3a6041d0695
Note that ALIGN_CST is still kept different in dec/frame.c for now,
because the values is 31 there, not 15. We might re-unite these two
later.
Change-Id: Ibbee607fac4eef02f175b56f0bb0ba359fda3b87
same functionality, but better code layout.
What changed:
* don't trash the palette_[] in EncodePalette(), so it can be re-used
* split generation of image from bit-stream coding
* move all the delta-palette code to delta_palettization.c, and only have 1 entry point there WebPSearchOptimalDeltaPalette()
* minimize the number of "#ifdef WEBP_EXPERIMENTAL_FEATURES" in vp8l.c
* clarify the TransformBuffer stuff. more clean-up to come here...
This should make experimenting with delta-palettization easier and more compartimentalized.
Change-Id: Iadaa90e6c5b9dabc7791aec2530e18c973a94610
some limitations: only for RGBA output,
and if reduction factor is not too small (dst_width > src_width / 128)
20-25% faster, ~4-6% global improvement total decoding.
Change-Id: I95366ddaa4a38e0a96bed754dfe790126f7bb84a
It's better to stay with a 32b fixed-point precision overall, otherwise
the C-version on ARM gets *slower*.
Actually, gcc ARM compiler optimizes some instructions pretty
well when WEBP_RESCALER_FIX is exactly 32, even in C.
Change-Id: I0eea97f7db5947470f5af355dee098eca81e178d
New palette compresses more than 20% better with minimum quality loss.
Tested on set of wikipedia images with command line:
cwebp -delta_palettization
Change-Id: I82ec7d513136599cd70386f607f634502eb9095d
Earlier, we stored a 1x1 frame for such frames. Now, we drop every such
frame and increase the duration of its previous frame instead.
Also, modify the anim_diff tool to handle animated images that are
equivalent, but have different number of frames.
Change-Id: I2688b1771e1f5f9f6a78e48ec81b01c3cd495403
The rounding and arithmetic is not the same as previously, to prevent overflow cases for large upscale factors.
We still rely on 32b x 32b -> 64b multiplies. Raised the fixed-point precision to 32b
so that we have some nice shifts from epi64 to epi32.
Changed rescaler_t type to 'uint32_t' in order to squeeze in all the precision required.
The MIPS code has been disabled because it's now out-of-sync. Will be fixed in
a subsequent CL when the dust settles.
~30-35% faster
Change-Id: I32e4ddc00933f1b1aa3463403086199fd5dad07b
* vertical expansion now uses bilinear interpolation
* heavily assumes that the alpha plane is decoded in full, not row-by-row
* split the RescalerExportRow and RescalerImportRow methods into Shrink
and Expand variants.
* MIPS implementation of ExportRowExpand is missing.
There's room for extra speed optim and code re-org, but let's keep that for later patches.
addresses https://code.google.com/p/webp/issues/detail?id=254
Change-Id: I8f12b855342bf07dd467fe85e4fde5fd814effdb
This is designed for the simple use-case where one wants to decode all
frames one-by-one in order.
Also, use this API in anim_util library, which is in turn used by
anim_diff tool.
Change-Id: Ie8b653c04e867d40fd23321b3dd41b87689656c7
This makes the chains more efficient and a larger variety of data is tested.
0.02 % compression gain at q 100, 0.05 % at default quality. 0.8 % speedup by
callgrind.
0.16 % compression gain for lossy alpha ?!
Change-Id: I888120133352799eb14f5f602c7f40ab404bd665
this allows scaling to a particular width/height while preserving the
source aspect ratio using WebPRescalerGetScaledDimensions().
Change-Id: I77b11528753290c1e9bb942ac761c215ccfb8701
using a *tmp_plane buffer to split a/r/g/b planes up appeared to
be the easiest route, compared to copy-pasting the whole code and
making it x_stride aware...
Change-Id: I0898ef1df62bd3e1713b77187b31b5eeef3832fe
allows the values to be used in preproc checks, fixing a
-Wunreachable-code warning in 64-bit builds where VP8L_WRITER_BITS != 16
Change-Id: Ie98dff4e8ef896436557c64d5da2c5d70228a730
Slightly faster on -m 0 -q 0, particularly for small images (50 x 75
image was 0.1 % faster on callgrind measurement).
Increases compression density by 0.005 % for the 1000 images, but small
images can improve even 0.5 % (about 4 bytes, depending on the
characteristics of the palette).
Change-Id: I94f568d396ac62a054a829abeeef3eb0af6b3f94
the x_add/x_sub increments were wrong for u/v in the upscaling case.
They shouldn't be left to the caller's discretion, but set up by
WebPRescalerInit to their exact necessary values.
-> Cleaned-up WebPRescalerInit() param list.
-> added safety asserts
-> removed the mips32/mips_r2 variant of "ImportRow" which were buggy prior
Change-Id: I347c75804d835811e7025de92a0758d7929dfc09
this moves the function outside the WEBP_USE_INTRINSICS check.
there's no alternative version and it's ~54% faster at the
function level and mildly faster overall
Change-Id: Ibc648e9ee35021d48901e05aa596aa01067796a2
a total impact of 1 % on encoding speed
This allows for performance neutral removal of the binary search
in cache bits selection. This will give a small improvement in
compression density.
Change-Id: If5d4d59460fa1924ce71af977320834a47c2054a
0.21 % compression density improvement for 1000 png corpus in
lossless mode
0.50 % compression density improvement for 1000 png corpus in
lossy mode
Change-Id: I14ee8c427ae5d3e116b0ee6695fcdea3321a319d
valgrind --tool=callgrind shows a 9 % speedup: 1021201984 ticks before vs.
927917709 after
-q 0 -m 0 -lossless ~/alpi/1.png
22.040 MP/s before
24.796 MP/s after
Change-Id: Iaab928167b3e20fb0d9401c6f8317a26c5a610b4
* changes:
lossless: combine the Huffman code with extra bits
lossless: Inlining add literal
lossless: simplify HashChainFindCopy heuristics
lossless: 0.5 % compression density improvement
lossless: Add zeroes into the predicted histograms.
lossless: encoding, don't compute unnecessary histo
lossless: Remove about 25 % of the speed degradation
Faster alpha coding for webp
lossless: rle mode not to accept lengths smaller than 4.
lossless: Less code for the entropy selection
lossless: 0.37 % compression density improvement
_BitScanReverse() takes an unsigned long*
http://msdn.microsoft.com/en-us/library/fbxyd7zd.aspx
fixes:
C4057: 'function': 'unsigned long *' differs in indirection to slightly
different base types from 'uint32_t *'
fixes issue #253
Change-Id: I0101ef7be18c7ed188b35e9b17e7f71290953786
do not do length 2 matches far away
speedup for non compressible data by inserting two literals at a time
when no matches are found
Change-Id: Ia8e033071f4186bb8148bb2bf13ca37586734aa3
Increases compression density by 0.03 % for lossy.
Speeds up at least one of the lossy alpha images by 20 %.
Palette entropy 'kludge' seems to save 1-2 % on alpha images.
Change-Id: I2116b8d81593ac8173bfba54a7c833997fca0804
share the computation between different modes
3-5 % speedup for lossless alpha
1 % for lossy alpha
no change in compression density
Change-Id: I5e31413b3efcd4319121587da8320ac4f14550b2
introduced in:
"lossless: 0.37 % compression density improvement"
Uses the statistics of red and blue histograms to decide if to run
cross color correction at all.
Improves compression density by 0.02 % or so.
Change-Id: I47429557e9cdbd9fa90c584696f241b17427d73f
No significant size degradation (+0.001 %) for 1000 image corpus
Fixes the 8 ms vs 2 ms degradation from:
"lossless: 0.37 % compression density improvement"
Change-Id: Id540169a305d9d5c6213a82b46c879761b3ca608
counting the entropy expectation for five different configurations:
palette
non-predicted
non-predicted with subtract green
predicted
predicted with subtract green
and choose the strategy with the smallest expected entropy
Change-Id: Iaaf209c0d565660a54a4f9b3959067afb9951960
this should be used in preference to free() for releasing memory
returned from WebPDecode*() / WebPEncode*(). this simplifies memory
management when working through language bindings
Change-Id: I15eb538a45390efc552fda8e5c251a3fbdc13c29
After several trials at re-organizing the main loop and accumulation scheme,
this is apparently the faster variant.
removed the SSE41 version, which is no longer faster now.
For some reason, the AVX variant seems to benefit most for the change.
Change-Id: Ib11ee18dbb69596cee1a3a289af8e2b4253de7b5
this moves the function outside the WEBP_USE_INTRINSICS check.
there's no alternative version and it's ~70% faster at the
function level and 1-2% faster overall
Change-Id: I59fb4918ec86b1ac3a47cbd5d05ce62f007461cb
Changed the code (again) to process 4 pixels at a time. Loop is more
involved, but overall it's faster.
Removed the SSE4.1 implementation which is now slower than SSE2.
Change-Id: I7734e371033ad8929ace7f7e1373ba930d9bb5f1
New implementations: SubtractGreenFromBlueAndRed and TransformColor
around 1-2% faster lossless encoding.
Change-Id: I1668e36fdc316ba55b3b798b91b4a3e36ce62861
DispatchAlpha* functions are hard to speed up, compared to SSE2.
ExtractAlpha sees a ~15% speed-up though.
Change-Id: I8715c2defecbc832f469eed7e6ffd012146b52de
over a 1000 image corpus
Single photograph benchmark:
Before:
Q=20: 2.560 MP/s
Q=40: 2.593 MP/s
Q=60: 1.795 MP/s
Q=80: 1.603 MP/s
Q=99: 1.122 MP/s
After:
Q=20: 3.334 MP/s
Q=40: 2.464 MP/s
Q=60: 2.009 MP/s
Q=80: 1.871 MP/s
Q=99: 1.163 MP/s
This CL allows for some further improvements that would not be possible
otherwise.
Change-Id: I61ba154beca2266cb96469281cf96e84a4412586
use vld1_dup_u8() rather than a separate ld+dup after the values were
zero extended; mildly faster at the function level
Change-Id: I1b3666a6aeb465722a1214dbc6d71c27689a7f89
VP8EncPredChroma8 improvements over ~20M pixels
left/top: ~67%
left-only: ~52%
top-only: ~57%
none: ~61%
based on dec_sse2 versions with minor changes to benefit from the linear
storage of the left boundary
Change-Id: Iee7e387fb2570b4eb5af5bfd123e9c2e9ea49c76
VP8EncPredLuma16 improvements over ~20M pixels
left/top: ~75%
left-only: ~47%
top-only: ~59%
none: ~63%
based on dec_sse2 versions with minor changes to benefit from the linear
storage of the left boundary
Change-Id: I7548be7214fa85c38fd11d30f5b8b271f437657d
structured extended feature flags require eax = 7; avoids incorrectly
detecting avx2 on some older processors that support avx.
for completeness also check for value=1 support used by the other
checks.
from [1]:
INPUT EAX = 0: Returns CPUID’s Highest Value for Basic Processor
Information and the Vendor Identification String
[1]
http://www.intel.com/content/www/us/en/processors/processor-identification-cpuid-instruction-note.html
Change-Id: I60b20d661a978d551614dbf7acdc25db19cb6046
* make VP8LPrefetchBits() safe wrt past-EOS reads
* set 'BitReader::bits_" to a safe shifting value upon EOS
no visible performance difference on x86
Change-Id: I0a4177928cfa81d5dfc9054b36a686eaa1bf8c65
Speed-wise equivalent on x86 and ARM (maybe a tad faster, hard to tell).
Note that the two 32-bit multiples are not strictly equivalent
to the 64-bit one, since we're missing one carry propagation.
In practice, no observable difference was seen because of this
slightly different hashing result.
Change-Id: I8f2381175eae1cb20dabf149e6b27e1768fba6ab
update makefile.unix to provide 'make extras' building instructions.
note: input ordering depends on WEBP_SWAP_16BIT_CSP for rgb565 and rgb4444
Change-Id: I6f22d32189d9ba2619146a9714cedabfe28e2ad0
When converting from video sources, the duration of current frame
is often unavailable until the next frame. So, we internally convert
timestamps to durations.
Change-Id: I20ad86361c22e014be7eb91f00d5d40108281351
use psadbw to perform top row summation; left remains in C as repacking
it into a vector to apply the same operation is too costly.
DC8uv: ~19% faster
DC8uvNoLeft: ~12% faster
Change-Id: I707c4f6177a65b5d1f2d3deeca87d2bb740185e2
use psadbw to perform top row summation; left remains in C as repacking
it into a vector to apply the same operation is too costly.
DC16: ~20% faster
DC16NoLeft: ~14% faster
Change-Id: I7ec3f8a6e5923f88a530f79fceb88d5001bef691
generates a stub function when the specific architecture is not enabled,
exposing a symbol in the module, avoiding a compiler warning
Change-Id: Ia9336e57466a9b5241b85c1c95838e91c9283147
had to rename few structs.
-> we can now include both vp8i.h and vp8enci.h without naming
conflicts.
Change-Id: Ib41b498f1b57aab3d6b796361afc45210ec75174
Visible speed-up, thanks to pshufb and pabsw and psignw use.
had to tweak configure.ac to make "smmintri.h" presence correctly
detected (we need to set the CPPFLAGS instead of the CFLAGS!)
Change-Id: I2ab99e16a27a64fdf1f09b2b4e30a5e74ccca080
allows the former to be inlined; negligible speed-up in most cases,
however this is structure is consistent with the rest of the optimized
modules
Change-Id: Ib080240b06f7a995b47f1906627850c355b82901
we look at average global improvement and stop when things are
moving slow, or when we had a quite good first iteration already
(means: the picture is "not difficult")
Change-Id: I8ab7d100353039b5b32bb5fac3fe03c8440c78d5
Speedup method StoreImageToBitMask by replacing the code to find histogram
index and Huffman tree codes at every iteration to a more optimal code that
updates these only when the current pixel (to write) crosses the histogram
tile-row boundary.
This change speeds up the StoreImageToBitMask method by 5%.
Change-Id: If01a1ccd7820f9a3a3e5bc449d070defa51be14b
the standard vtbl functions are available there [1][2].
based on a patch from: aaroncrespo
fixes issue #243.
[1]
http://adcdownload.apple.com//Developer_Tools/Xcode_6.3_beta/Xcode_6.3_beta_Release_Notes.pdf
[2] Apple LLVM Compiler Version 6.1
- Xcode 6.3 updates the Apple LLVM compiler to version 6.1.0.
[...]
Support for the arm64 architecture has been significantly revised to
align with ARM's implementation, where the most visible impact is that a
few of the vector intrinsics have changed to match ARM's specifications.
Change-Id: I79a0016f44b9dbe36d0373f7f00a50ab3c2ca447
The MIPS code for cost is not updated yet, that's why i keep Residual::*cost
around for now. Should be removed in favor of *costs later.
Change-Id: Id1d09a8c37ea8c5b34ad5eb8811d6a3ec6c4d89f
affected functions: SimpleVFilter16, SimpleHFilter16,
SimpleVFilter16i and SimpleHFilter16i
noticed bug in FilterLoop26 (fix included in this patch)
Change-Id: I72d9c1e45cbac6393eba52bb549b04924d463e30
removes circular dependency between dsp and enc.
since:
a987fae MIPS: dspr2: added optimization for function GetResidualCost
Change-Id: Ifeb8fc02de89e2ba982ed7ffacd925d649bfec3c
kGammaFix is now only defined with USE_GAMMA_COMPRESSION;
fixes:
use of undeclared identifier 'kGammaFix'
Change-Id: Ib1e2f410eff9b83be065894f88181f91dd2776e1
set/get residual C functions moved to new file in src/dsp
mips32 version of GetResidualCost moved to new file
Change-Id: I7cebb7933a89820ff28c187249a9181f281081d2
the input to the function is non-const and the pointer being operated is
being free'd; removes an unnecessary cast in the process
Change-Id: Ic515ed672ddf7f8e4e36eeac696ff7aa8a3652f7
Updated the near-lossless level mapping and make it correlated to lossy
quality i.e 100 => minimum loss (in-fact no-loss) and the visual-quality loss
increases with decrease in near-lossless level (quality) till value 0.
The new mapping implies following (PSNR) loss-metric:
-near_lossless 100: No-loss (bit-stream same as -lossless).
-near_lossless 80: Very very high PSNR (around 54dB).
-near_lossless 60: Very high PSNR (around 48dB).
-near_lossless 40: High PSNR (around 42dB).
-near_lossless 20: Moderate PSNR (around 36dB).
-near_lossless 0: Low PSNR (around 30dB).
Change-Id: I930de4b18950faf2868c97d42e9e49ba0b642960
DitherRow() only checks this value, not 'skip_' so previously it was
uninitialized for these blocks.
Change-Id: I0f698b81854ee9d91edacb51c1e3bdab9cba96f2
similar to:
1ba61b0 enable NEON intrinsics in aarch64 builds
vtbl1_u8 is available everywhere but Xcode-based iOS arm64 builds, use
vtbl1q_u8 there.
performance varies based on the input, 1-3% on encode was observed
Change-Id: Ifec35b37eb856acfcf69ed7f16fa078cd40b7034
AnalyzeSubtractGreen constitutes about 8-10% of the comression CPU cycles.
Statistically, subtract-green is proved to be useful for most of the
non-palette compression. So instead of evaluating the entropy (by calling
AnalyzeSubtractGreen) apply subtract-green transform for the low-effort
compression.
This changes speeds up the compression at m=0 by 8-10% (with very slight loss
of 0.07% in the compression density).
Change-Id: I9797dc39437ae089716acb14631bbc77d367acf4
Speed up AnalyzeSubtractGreen by looping through the image pixel once to
compute the two histograms.
AnalyzeEntropy code cleanup.
Removed some 'if' conditions and pointer indirections inside pixel iterate loop.
Change-Id: Ia65e3033988ff67df8e3ecce19d6e34cfc76358e
Enable the WebP near-lossless feature by pre-processing the image to smoothen
the pixels.
On a 1000 PNG image corpus, for which WebP lossless (default settings) gets
25% compression gains, following is the performance of near-lossless feature
at various '-near_lossless' levels:
-near_lossless 90: 30% (very very high PSNR 54-60dB)
-near_lossless 75: 38% (very high PSNR 48-54dB)
-near_lossless 50: 45% (high PSNR 42-48dB)
-near_lossless 25: 48% (moderate PSNR 36-42dB)
-near_lossless 10: 50% (PSNR 30-36dB)
WebP near-lossless is specifically useful for discrete-tone images like
line-art, icons etc.
Change-Id: I7d12a2c9362ccd076d09710ea05c85fa64664c38
Some frames that were previously selected as key-frames were incorrectly
being reset to sub-frames.
Change-Id: Iee342dbb9a9aec144b8185c3b54ca56aa7038bfb
The 'inverse' variants are harder to parallelize, since
the result of filtering is used for prediction.
The 'direct' way is relatively easier.
The heavy bottleneck left for optimization is still GradientUnfilter()
Change-Id: I358008f492a887e8fff6600cb27857b18dee86e9
