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add lossless quick encoding functions to the public API

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New functions:
   WebPEncodeLosslessRGB()
   WebPEncodeLosslessBGR()
   WebPEncodeLosslessRGBA()
   WebPEncodeLosslessBGRA()

Change-Id: Id56da7569eee80c57de8f1f053fb87b217d33a4b
This commit is contained in:
Pascal Massimino 2012-07-17 11:56:24 -07:00
parent 4c1f5d6435
commit c2416c9b61
3 changed files with 54 additions and 5 deletions
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14
README
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@ -263,6 +263,20 @@ size_t WebPEncodeBGRA(const uint8_t* bgra, int width, int height, int stride,
They will convert raw RGB samples to a WebP data. The only control supplied
is the quality factor.
There are some variants for using the lossless format:
size_t WebPEncodeLosslessRGB(const uint8_t* rgb, int width, int height,
int stride, uint8_t** output);
size_t WebPEncodeLosslessBGR(const uint8_t* bgr, int width, int height,
int stride, uint8_t** output);
size_t WebPEncodeLosslessRGBA(const uint8_t* rgba, int width, int height,
int stride, uint8_t** output);
size_t WebPEncodeLosslessBGRA(const uint8_t* bgra, int width, int height,
int stride, uint8_t** output);
Of course in this case, no quality factor is needed since the compression
occurs without loss of the input values, at the expense of larger output sizes.
Advanced encoding API:
----------------------

20
src/enc/picture.c
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@ -1008,7 +1008,8 @@ int WebPPictureDistortion(const WebPPicture* const pic1,
typedef int (*Importer)(WebPPicture* const, const uint8_t* const, int);
static size_t Encode(const uint8_t* rgba, int width, int height, int stride,
Importer import, float quality_factor, uint8_t** output) {
Importer import, float quality_factor, int lossless,
uint8_t** output) {
WebPPicture pic;
WebPConfig config;
WebPMemoryWriter wrt;
@ -1019,6 +1020,8 @@ static size_t Encode(const uint8_t* rgba, int width, int height, int stride,
return 0; // shouldn't happen, except if system installation is broken
}
config.lossless = !!lossless;
pic.use_argb_input = !!lossless;
pic.width = width;
pic.height = height;
pic.writer = WebPMemoryWrite;
@ -1039,7 +1042,7 @@ static size_t Encode(const uint8_t* rgba, int width, int height, int stride,
#define ENCODE_FUNC(NAME, IMPORTER) \
size_t NAME(const uint8_t* in, int w, int h, int bps, float q, \
uint8_t** out) { \
return Encode(in, w, h, bps, IMPORTER, q, out); \
return Encode(in, w, h, bps, IMPORTER, q, 0, out); \
}
ENCODE_FUNC(WebPEncodeRGB, WebPPictureImportRGB);
@ -1049,6 +1052,19 @@ ENCODE_FUNC(WebPEncodeBGRA, WebPPictureImportBGRA);
#undef ENCODE_FUNC
#define LOSSLESS_DEFAULT_QUALITY 70.
#define LOSSLESS_ENCODE_FUNC(NAME, IMPORTER) \
size_t NAME(const uint8_t* in, int w, int h, int bps, uint8_t** out) { \
return Encode(in, w, h, bps, IMPORTER, LOSSLESS_DEFAULT_QUALITY, 1, out); \
}
LOSSLESS_ENCODE_FUNC(WebPEncodeLosslessRGB, WebPPictureImportRGB);
LOSSLESS_ENCODE_FUNC(WebPEncodeLosslessBGR, WebPPictureImportBGR);
LOSSLESS_ENCODE_FUNC(WebPEncodeLosslessRGBA, WebPPictureImportRGBA);
LOSSLESS_ENCODE_FUNC(WebPEncodeLosslessBGRA, WebPPictureImportBGRA);
#undef LOSSLESS_ENCODE_FUNC
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)

19
src/webp/encode.h
View File

@ -30,6 +30,9 @@ WEBP_EXTERN(int) WebPGetEncoderVersion(void);
// Returns the size of the compressed data (pointed to by *output), or 0 if
// an error occurred. The compressed data must be released by the caller
// using the call 'free(*output)'.
// These functions compress using the lossy format, and the quality_factor
// can go from 0 (smaller output, lower quality) to 100 (best quality,
// larger output).
WEBP_EXTERN(size_t) WebPEncodeRGB(const uint8_t* rgb,
int width, int height, int stride,
float quality_factor, uint8_t** output);
@ -43,6 +46,22 @@ WEBP_EXTERN(size_t) WebPEncodeBGRA(const uint8_t* bgra,
int width, int height, int stride,
float quality_factor, uint8_t** output);
// These functions are the equivalent of the above, but compressing in a
// lossless manner. Files are usually larger than lossy format, but will
// not suffer any compression loss.
WEBP_EXTERN(size_t) WebPEncodeLosslessRGB(const uint8_t* rgb,
int width, int height, int stride,
uint8_t** output);
WEBP_EXTERN(size_t) WebPEncodeLosslessBGR(const uint8_t* bgr,
int width, int height, int stride,
uint8_t** output);
WEBP_EXTERN(size_t) WebPEncodeLosslessRGBA(const uint8_t* rgba,
int width, int height, int stride,
uint8_t** output);
WEBP_EXTERN(size_t) WebPEncodeLosslessBGRA(const uint8_t* bgra,
int width, int height, int stride,
uint8_t** output);
//------------------------------------------------------------------------------
// Coding parameters