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/*===========================================================================*
- Copyright 2010 Google Inc.
-
- This code is licensed under the same terms as WebM:
- Software License Agreement: http://www.webmproject.org/license/software/
- Additional IP Rights Grant: http://www.webmproject.org/license/additional/
*===========================================================================*/
/*
* Encoding/Decoding of WebP still image compression format.
*
* 1. WebPDecode: Takes an array of bytes (string) corresponding to the WebP
* encoded image and generates output in the YUV format with
* the color components U, V subsampled to 1/2 resolution along
* each dimension.
*
* 2. YUV420toRGBA: Converts from YUV (with color subsampling) such as produced
* by the WebPDecode routine into 32 bits per pixel RGBA data
* array. This data array can be directly used by the Leptonica
* Pix in-memory image format.
*
* 3. WebPEncode: Takes a Y, U, V data buffers (with color components U and V
* subsampled to 1/2 resolution) and generates the WebP string
*
* 4. RGBAToYUV420: Generates Y, U, V data (with color subsampling) from 32 bits
* per pixel RGBA data buffer. The resulting YUV data can be
* directly fed into the WebPEncode routine.
*
* 5. AdjustColorspace:
*
* 6. AdjustColorspaceBack:
*/
#ifndef THIRD_PARTY_VP8_VP8IMG_H_
#define THIRD_PARTY_VP8_VP8IMG_H_
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
typedef unsigned char uint8;
typedef unsigned int uint32;
typedef enum WebPResultType {
webp_success = 0,
webp_failure = -1
} WebPResult;
/* Takes an array of bytes (string) corresponding to the WebP
* encoded image and generates output in the YUV format with
* the color components U, V subsampled to 1/2 resolution along
* each dimension.
* Input:
* 1. data: the WebP data stream (array of bytes)
* 2. data_size: count of bytes in the WebP data stream
*
* Output:
* 3. p_Y/p_U/p_V : pointer to the Y/U/V data buffer (this routine will
* allocate memory for the buffer, fill the buffer with
* appropriate data and transfer owner ship of the buffer
* to caller. Caller is reponsible for freeing the memory).
* Note that the memory for Y, U, V buffers is alloacted
* in one chunk, hence one should call free(*p_Y) only.
* Do not try to free the U and V buffers.
*
* 6. p_width: this routine returns the width of the decoded image here
* 7. p_height: this routine returns the width of the decoded image here
* Return: success/failure
*/
WebPResult WebPDecode(const uint8* data,
int data_size,
uint8** p_Y,
uint8** p_U,
uint8** p_V,
int* p_width,
int* p_height);
/* WebPEncode: Takes a Y, U, V data buffers (with color components U and V
* subsampled to 1/2 resolution) and generates the WebP string.
* Input:
* 1, 2, 3. Y, U, V: The input YUV data buffers
* 4, 5. y_width, y_height: The width and height of the image whose data
* is in Y, U, V. This matches the Y plane. The U
* and V planes typically have 1/2 width and
* height.
* 6. y_stride: The width (in bytes) of one row of Y data. This may not
* match width if there is end of row padding (e.g., for 32
* bit row alignment).
* 7. QP: the quantization parameter. This parameter controls the
* compression vs quality tradeoff. Use smaller numbers for better
* quality (compression will be lesser) and vice versa. 20 is a
* good optimal value.
* Output:
* 8. p_out: the output array of bytes corresponding to the encoded WebP
* image. This routine allocates memory for the buffer, fills it
* with appropriate values and transfers ownership to caller.
* Caller responsible for freeing of memory.
* Return: success/failure
*/
WebPResult WebPEncode(const uint8* Y,
const uint8* U,
const uint8* V,
int y_width,
int y_height,
int y_stride,
int uv_width,
int uv_height,
int uv_stride,
int QP,
unsigned char** p_out,
int* p_out_size_bytes,
double* psnr);
/* Converts from YUV (with color subsampling) such as produced by the WebPDecode
* routine into 32 bits per pixel RGBA data array. This data array can be
* directly used by the Leptonica Pix in-memory image format.
* Input:
* 1, 2, 3. Y, U, V: the input data buffers
* 4. pixwpl: the desired words per line corresponding to the supplied
* output pixdata.
* 5. width, height: the dimensions of the image whose data resides in Y,
* U, V.
* Output:
* 6. pixdata: the output data buffer. Caller should allocate
* height * pixwpl bytes of memory before calling this routine.
*/
void YUV420toRGBA(uint8* Y,
uint8* U,
uint8* V,
int words_per_line,
int width,
int height,
uint32* pixdata);
/* Generates Y, U, V data (with color subsampling) from 32 bits
* per pixel RGBA data buffer. The resulting YUV data can be directly fed into
* the WebPEncode routine.
* Input:
* 1. pix data input rgba data buffer
* 2. words per line corresponding to pixdata
* 3, 4. image width and height respectively
* Output:
* 5, 6, 7. Output YUV data buffers
*/
void RGBAToYUV420(uint32* pixdata,
int words_per_line,
int width,
int height,
uint8* Y,
uint8* U,
uint8* V);
/* This function adjust from YUV420J (jpeg decoding) to YUV420 (webp input)
* Hints: http://en.wikipedia.org/wiki/YCbCr
*/
void AdjustColorspace(uint8* Y, uint8* U, uint8* V, int width, int height);
/* Inverse function: convert from YUV420 to YUV420J */
void AdjustColorspaceBack(uint8* Y, uint8* U, uint8* V, int width, int height);
/* Checks WebP image header and outputs height and width information of
* the image
*
* Input:
* 1. data: the WebP data stream (array of bytes)
* 2. data_size: count of bytes in the WebP data stream
*
* Outut:
* width/height: width and height of the image
*
* Return: success/failure
*/
WebPResult WebPGetInfo(const uint8* data,
int data_size,
int *width,
int *height);
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* THIRD_PARTY_VP8_VP8IMG_H_ */