mirror of
https://github.com/webmproject/libwebp.git
synced 2024-12-25 21:28:22 +01:00
README: cosmetics
- update swig function references - remove references to decode_vp8.h (no longer installed) - add lossless references - some grammar/spelling changes Change-Id: Icebfbcf6f638762f42d844b6bd3c0129c64d9340
This commit is contained in:
parent
3e5bbe1c2e
commit
c37c23e594
57
README
57
README
@ -49,11 +49,13 @@ will build the binaries examples/cwebp and examples/dwebp, along
|
||||
with the static library src/libwebp.a. No system-wide installation
|
||||
is supplied, as this is a simple alternative to the full installation
|
||||
system based on the autoconf tools (see below).
|
||||
Please refer the makefile.unix for additional details and customizations.
|
||||
Please refer to the makefile.unix for additional details and customizations.
|
||||
|
||||
Using autoconf tools:
|
||||
---------------------
|
||||
./autogen.sh
|
||||
When building from git sources, you will need to run autogen.sh to generate the
|
||||
configure script.
|
||||
|
||||
./configure
|
||||
make
|
||||
make install
|
||||
@ -61,7 +63,6 @@ make install
|
||||
should be all you need to have the following files
|
||||
|
||||
/usr/local/include/webp/decode.h
|
||||
/usr/local/include/webp/decode_vp8.h
|
||||
/usr/local/include/webp/encode.h
|
||||
/usr/local/include/webp/types.h
|
||||
/usr/local/lib/libwebp.*
|
||||
@ -85,17 +86,22 @@ Currently the following functions are mapped:
|
||||
Decode:
|
||||
WebPGetDecoderVersion
|
||||
WebPGetInfo
|
||||
WebPDecodeRGB
|
||||
WebPDecodeRGBA
|
||||
WebPDecodeARGB
|
||||
WebPDecodeBGR
|
||||
WebPDecodeBGRA
|
||||
WebPDecodeBGR
|
||||
WebPDecodeRGB
|
||||
|
||||
Encode:
|
||||
WebPGetEncoderVersion
|
||||
WebPEncodeRGB
|
||||
WebPEncodeRGBA
|
||||
WebPEncodeBGR
|
||||
WebPEncodeBGRA
|
||||
WebPEncodeRGB
|
||||
WebPEncodeBGR
|
||||
WebPEncodeLosslessRGBA
|
||||
WebPEncodeLosslessBGRA
|
||||
WebPEncodeLosslessRGB
|
||||
WebPEncodeLosslessBGR
|
||||
|
||||
Java bindings:
|
||||
|
||||
@ -111,9 +117,13 @@ decoding (dwebp) images.
|
||||
|
||||
The easiest use should look like:
|
||||
cwebp input.png -q 80 -o output.webp
|
||||
which will convert the input PNG or JPEG file to a WebP file using a
|
||||
quality factor of 80 on a 0->100 scale (0 being the lowest quality,
|
||||
100 being the best. Default value is 75).
|
||||
which will convert the input file to a WebP file using a quality factor of 80
|
||||
on a 0->100 scale (0 being the lowest quality, 100 being the best. Default
|
||||
value is 75).
|
||||
You might want to try the -lossless flag too, which will compress the source
|
||||
(in RGBA format) without any loss. The -q quality parameter will in this case
|
||||
control the amount of processing time spent trying to make the output file as
|
||||
small as possible.
|
||||
|
||||
A longer list of options is available using the -longhelp command line flag:
|
||||
|
||||
@ -192,10 +202,11 @@ Namely:
|
||||
but with better quality.
|
||||
Typical value is around '75'.
|
||||
* 'f' option directly links to the filtering strength used by the codec's
|
||||
in-loop processing. The higher, the smoother will highly-compressed area
|
||||
look. This is particularly useful when aiming at very small files.
|
||||
Typical values are around 20-30. Note that using the option -strong will
|
||||
change the type of filtering. Use "-f 0" to turn filtering off.
|
||||
in-loop processing. The higher the value, the smoother the
|
||||
highly-compressed area will look. This is particularly useful when aiming
|
||||
at very small files. Typical values are around 20-30. Note that using the
|
||||
option -strong will change the type of filtering. Use "-f 0" to turn
|
||||
filtering off.
|
||||
* 'm' controls the trade-off between encoding speed and quality. Default is 4.
|
||||
You can try -m 5 or -m 6 to explore more (time-consuming) encoding
|
||||
possibilities. A lower value will result in faster encoding at the expense
|
||||
@ -342,20 +353,18 @@ This is mainly just one function to call:
|
||||
|
||||
#include "webp/decode.h"
|
||||
uint8_t* WebPDecodeRGB(const uint8_t* data, size_t data_size,
|
||||
int *width, int *height);
|
||||
int* width, int* height);
|
||||
|
||||
Please have a look at the file src/webp/decode.h for the details.
|
||||
There are variants for decoding in BGR/RGBA/ARGB/BGRA order, along with
|
||||
decoding to raw Y'CbCr samples. One can also decode the image directly into a
|
||||
pre-allocated buffer.
|
||||
|
||||
To detect a WebP file and gather picture's dimensions, the function:
|
||||
To detect a WebP file and gather the picture's dimensions, the function:
|
||||
int WebPGetInfo(const uint8_t* data, size_t data_size,
|
||||
int *width, int *height);
|
||||
int* width, int* height);
|
||||
is supplied. No decoding is involved when using it.
|
||||
|
||||
A lower-level API is available from the header file <webp/decode_vp8.h>
|
||||
|
||||
Incremental decoding API:
|
||||
=========================
|
||||
|
||||
@ -383,15 +392,15 @@ or by just mentioning the new size of the transmitted data:
|
||||
|
||||
WebPIUpdate(idec, buffer, size_of_transmitted_buffer);
|
||||
|
||||
Note that 'buffer' can be modified between each calls to WebPIUpdate, in
|
||||
Note that 'buffer' can be modified between each call to WebPIUpdate, in
|
||||
particular when the buffer is resized to accommodate larger data.
|
||||
|
||||
These functions will return the decoding status: either VP8_STATUS_SUSPENDED if
|
||||
decoding is not finished yet, or VP8_STATUS_OK when decoding is done.
|
||||
Any other status is an error condition.
|
||||
decoding is not finished yet or VP8_STATUS_OK when decoding is done. Any other
|
||||
status is an error condition.
|
||||
|
||||
The idec object must always be released (even upon an error condition)
|
||||
by calling: WebPDelete(idec).
|
||||
The 'idec' object must always be released (even upon an error condition) by
|
||||
calling: WebPDelete(idec).
|
||||
|
||||
To retrieve partially decoded picture samples, one must use the corresponding
|
||||
method: WebPIDecGetRGB or WebPIDecGetYUV.
|
||||
|
Loading…
Reference in New Issue
Block a user