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
-> WebPImageReader
Introduce a variant of image-guessing function that returns a reader
directly: WebPGuessImageReader()
Change-Id: I5ddc53024fcf941e33d997b2be6aa1a963d939ab
adds a generic examples/image_dec.[ch] entry point too.
WebPGuessImageType() can be used to infer image type.
Change-Id: I8337e7b6ad91863c9cf118e4791668d2d175079b
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
