picture->error_code can be looked up for finer error diagnose.
Added readable error messages to cwebp too.
Should close bug #75 (http://code.google.com/p/webp/issues/detail?id=75)
Change-Id: I8889d06642d90702f698cd5c27441a058ddb3636
+ 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
we'll always encode using absolute value, not relative ones.
Both methods use the same number of bits, so we'll go for the
simpler and most robust one.
+ add some extra checks about pic->u/v being NULL.
Change-Id: I98ea01a1a6b133ab3c816c0fbc50e18269bd2098
converts PNG & JPEG to WebP
This is an experimental early version, with lot of room
of later optimizations in both speed and quality.
Compile with the usual `./configure && make`
Command line example is examples/cwebp
Usage:
cwebp [options] -q quality input.png -o output.webp
where 'quality' is between 0 (poor) to 100 (very good).
Typical value is around 80.
More encoding options with 'cwebp -longhelp'
Change-Id: I577a94f6f622a0c44bdfa9daf1086ace89d45539
