There was 1 unneeded sample line allocated for the filter cache in of simple filtering.
+ Add an explaining comment.
Change-Id: I775a596c8b8643e773e0eade8aa341dc23fb290f
+ 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
libvpx (and ffvp8) implementations are completely skipping the deblocking
step if loop_filter_level is 0, which is _not_ equivalent to performing
the loop-filtering with a 0 value for loop_filter_level. In the latter case
(which we followed), few pixels were modified here and there and you could
observe off-by-1 errors on few places.
This patch will reconcile the 3 implementations (since the difference
is minor, skipping the deblocking step will save CPU for virtually
no visible difference).
The spec will be made clearer about the expected behaviour:
* if the global loop_filter_level is 0, turn deblocking off.
* if it's not 0 but the local loop_filter_level ends up being 0 for whatever
reason (lf_delta, mode delta, ref delta, etc.) on a particular
macroblock, skip the deblocking too.
Change-Id: I157f1f8de463b8a76caddb3f347b7fbc7bd527d2
