New API options: WebPDecoderOptions.flip and 'dwebp -flip ...'
it uses negative stride trick.
Also changed the decoder code to support user-supplied
buffers with negative stride, independently of the
WebPDecoderOptions.flip value.
Change-Id: I4dc0d06f0c87e51a3f3428be4fee2d6b5ad76053
Even at high quality setting, the U/V quantizer step is limited
to 4 which can lead to banding on gradient.
This option allows to selectively apply some randomness to
potentially flattened-out U/V blocks and attenuate the banding.
This option is off by default in 'dwebp', but set to -dither 50
by default in 'vwebp'.
Note: depending on the number of blocks selectively dithered,
we can have up to a 10% slow-down in decoding speed it seems.
Change-Id: Icc2446007f33ddacb60b3a80a9e63f2d5ad162de
rather than symlink the webm/vpx terms, use the same header as libvpx to
reference in-tree files
based on the discussion in:
https://codereview.chromium.org/12771026/
Change-Id: Ia3067ecddefaa7ee01550136e00f7b3f086d4af4
The output surface CAN be changed inbetween calls to
WebPIUpdate() or WebPIAppend(), but with precautions.
Change-Id: I899afbd95738a6a8e0e7000f8daef3e74c99ddd8
If a NULL pre-allocated buffer is passed, a buffer will be automatically
allocated.
+ add some parameter checks.
reported in http://code.google.com/p/webp/issues/detail?id=139
Change-Id: I9e14ed97db30ee12e46b5e92aac7eeaaeb99bfd5
Change-Id: I36d3765e94d2b5529b321c186ccee1744785c5b3
fixes:
error: ISO C++ forbids forward references to 'enum' types
since:
28d25c8 replace 'typedef struct {} X;" by "typedef struct X X; struct X {};"
Put emphasis on RGBA decoding instead of RGB/BGR
Clarify doc at some rough spots
Misc typo fix and cosmetics
Change-Id: Ic5fcfcc5bf4d612c5de23b0a5499f1fadde55bfe
minor revision shouldn't matter, we only check major revision number.
Bumped all version numbers so that incompatibility starts *now*
Change-Id: Id06c20f03039845ae4cfb3fd121807b931d67ee4
The new modes are
MODE_rgbA
MODE_bgrA
MODE_Argb
MODE_rgbA_4444
It's binary incompatible, since the enums changed.
While at it, i removed the now unneeded KeepAlpha methods.
-> Saved ~12k of code!
* made explicit mention that alpha_plane is persistent,
so we have access to the full alpha plane data at all time.
Incremental decoding of alpha was planned for, but not
implemented. So better not dragged this constaint for now
and make the code easier until we revisit that.
Change-Id: Idaba281a6ca819965ca062d1c23329f36d90c7ff
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
Add WEBP_EXTERN(type) macro which should make Windows DLL builds simpler
by allowing the signature to be changed.
Change-Id: I0cfa45dff779985680b1a38ddff30973a0d26639
RGB565 and ARGB4444 are only supported through the advanced decoding API.
ARGB being somewhat generic, there's an easy WebPDecodeARGB()
new function for convenience.
Patch by Vikas Arora (vikaas dot arora at gmail dot com)
Change-Id: Ic7b6f72bd70aca458d14e7fdd23679212430ebca
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
The object WebPIDecoder is available to store the
decoding state. The flow is typically:
WebPIDecoder* const idec = WebPINew(mode);
while (has_more_data) {
// ... (get additional data)
status = WebPIAppend(idec, new_data, new_data_size);
if (status != VP8_STATUS_SUSPENDED ||
break;
}
// The above call decodes the current available buffer.
// Part of the image can now be refreshed by calling to
// WebPIDecGetRGB()/WebPIDecGetYUV() etc.
}
WebPIDelete(idec);
Doing so, one can try and decode new macroblocks everytime fresh
bytes are available.
There's two operating modes: either appending fresh bytes, or
updating the whole buffer with additional data in the end.
The latter requires less memcpy()'s
main patch by Somnath Banerjee (somnath at google.com)
Change-Id: Ie81cbd0b50f175743af06b1f964de838b9a10a4a
