alpha information is not to be found at RIFF chunks level, not
in the VP8 bitstream (that was a tmp hack)
Change-Id: Idd1629c696b03c26f6f30650d7216f627f1761df
- Fix the off-by-one diff when cropping with simple-filter.
- Fix a bug in incremental decoding in case of alpha.
- In VP8FinishRow(), do not decode alpha when y_start > y_end.
- Correct output of alpha channel for MODE_ARGB.
- Correct output of alpha channel for MODE_RGBA_4444.
Change-Id: I785763a2a704b973cc742ad93ffbb53699d1fc0a
Extend WebP decode functionality to extract Alpha data (support ALPH
chunk) and decode the Alpha plane using Alpha (utils/alpha) core-lib.
Change-Id: I6f0ee1b189c13caba3c1dd9b681383bfd00aa212
- Move common defines to dec/webpi.h
- Regularize naming and parameters of various "CheckAndSkip" functions.
Also they return VP8StatusCode for clarity.
- Move WebP header/chunk parsing functions to webpi.h
- Fix a bug in static function GetFeatures()
Change-Id: Ibc3da4ba210d860551724dc40741959750d66b89
To be enabled with the flag WEBP_USE_THREAD.
For now it's only available on unix (pthread), when using Makefile.unix
Will be switched on more generally later.
In-loop filtering and output (=rescaling/yuv->rgb conversion)
is done in parallel to bitstream decoding, lagging 1 row behind.
Example:
examples/dwebp bryce.webp -v
Time to decode picture: 0.680s
examples/dwebp bryce.webp -v -mt
Time to decode picture: 0.515s
Change-Id: Ic30a897423137a3bdace9c4e30465ef758fe53f2
You can now use WebPDecBuffer, WebPBitstreamFeatures and WebPDecoderOptions
to have better control over the decoding process (and the speed/quality tradeoff).
WebPDecoderOptions allow to:
- turn fancy upsampler on/off
- turn in-loop filter on/off
- perform on-the-fly cropping
- perform on the-fly rescale
(and more to come. Not all features are implemented yet).
On-the-fly cropping and scaling allow to save quite some memory
(as the decoding operation will now scale with the output's size, not
the input's one). It saves some CPU too (since for instance,
in-loop filtering is partially turned off where it doesn't matter,
and some YUV->RGB conversion operations are ommitted too).
The scaler uses summed area, so is mainly meant to be used for
downscaling (like: for generating thumbnails or previews).
Incremental decoding works with these new options.
More doc to come soon.
dwebp is now using the new decoding interface, with the new flags:
-nofancy
-nofilter
-crop top left width height
-scale width height
Change-Id: I08baf2fa291941686f4ef70a9cc2e4137874e85e
+ add a simple rescaling function: WebPPictureRescale() for encoding
+ clean-up the memory managment around the alpha plane
+ fix some includes path by using "../webp/xxx.h" instead of "webp/xxx.h"
New flags for 'cwebp':
-resize <width> <height>
-444 (no effect)
-422 (no effect)
-400
Change-Id: I25a95f901493f939c2dd789e658493b83bd1abfa
This is a (minor) bitstream change: if the 'color_space' bit is set to '1'
(which is normally an undefined/invalid behaviour), we add extra data at the
end of partition #0 (so-called 'extensions')
Namely, we add the size of the extension data as 3 bytes (little-endian),
followed by a set of bits telling which extensions we're incorporating.
The data then _preceeds_ this trailing tags.
This is all experimental, and you'll need to have
'#define WEBP_EXPERIMENTAL_FEATURES' in webp/types.h to enable this code
(at your own risk! :))
Still, this hack produces almost-valid WebP file for decoders that don't
check this color_space bit. In particular, previous 'dwebp' (and for instance
Chrome) will recognize this files and decode them, but without the alpha
of course. Other decoder will just see random extra stuff at the end of
partition #0.
To experiment with the alpha-channel, you need to compile on Unix platform
and use PNGs for input/output.
If 'alpha.png' is a source with alpha channel, then you can try (on Unix):
cwebp alpha.png -o alpha.webp
dwebp alpha.webp -o test.png
cwebp now has a '-noalpha' flag to ignore any alpha information from the
source, if present.
More hacking and experimenting welcome!
Change-Id: I3c7b1fd8411c9e7a9f77690e898479ad85c52f3e
going down to strict -ansi c89 is quite overkill (no 'inline',
and /* */-style comments).
But with these fixes, the code compiles with the stringent flags:
-Wextra -Wold-style-definition -Wmissing-prototypes
-Wmissing-declarations and -Wdeclaration-after-statement
Change-Id: I36222f8f505bcba3d9d1309ad98b5ccb04ec17e3
WebPGetDecoderVersion() and WebPGetEncoderVersion()
will not return 0.1.2 encoded as 0x000102
dwebp and cwebp also have a new "-version" flag
Change-Id: I4fb4b5a8fc4e53681a386ff4b74fffb639fa237a
non-zero dc-bit was mixed with non-zero ac-bit, preventing
finer optimization during VP8ReconstructBlock.
Depending on sparsity, i see 2-5% gain on average.
Change-Id: I7f34f18d0701c77837de3540b732e5b7d85d7c5d
(this makes initialization easier and will be helpful for incremental
decoding).
Modify ParsePartitions() to accommodate for truncated input.
Change-Id: I62f52078d6b7a2314a11880a20d9eac5b4714bd0
This will make the decoder skip the filtering process if needed,
resulting in speed-up, but also non-compliant (blocky?) output
+ Add a versioning check for VP8InitIo(), since we've adding a field to VP8Io
+ add some more error checks while at it
Change-Id: I4e9899edc24ecf8600cbb27aa4038490b7b2cef3
