mirror of
https://github.com/webmproject/libwebp.git
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2e3e8b2ef5
to 'clean up' the fully-transparent area and make it more compressible new cwebp flags: -alpha_cleanup (off by default, since gain is not 100% guaranteed) Change-Id: I74d77e1915eee146584cd61c9c1132a41db922eb
302 lines
14 KiB
C
302 lines
14 KiB
C
// Copyright 2011 Google Inc. All Rights Reserved.
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//
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// This code is licensed under the same terms as WebM:
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// Software License Agreement: http://www.webmproject.org/license/software/
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// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
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// -----------------------------------------------------------------------------
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//
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// WebP encoder: main interface
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#ifndef WEBP_WEBP_ENCODE_H_
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#define WEBP_WEBP_ENCODE_H_
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#include <stdlib.h>
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#include "./types.h"
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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#define WEBP_ENCODER_ABI_VERSION 0x0003
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// Return the encoder's version number, packed in hexadecimal using 8bits for
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// each of major/minor/revision. E.g: v2.5.7 is 0x020507.
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WEBP_EXTERN(int) WebPGetEncoderVersion(void);
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//------------------------------------------------------------------------------
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// One-stop-shop call! No questions asked:
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// Returns the size of the compressed data (pointed to by *output), or 0 if
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// an error occurred. The compressed data must be released by the caller
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// using the call 'free(*output)'.
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WEBP_EXTERN(size_t) WebPEncodeRGB(const uint8_t* rgb,
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int width, int height, int stride,
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float quality_factor, uint8_t** output);
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WEBP_EXTERN(size_t) WebPEncodeBGR(const uint8_t* bgr,
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int width, int height, int stride,
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float quality_factor, uint8_t** output);
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WEBP_EXTERN(size_t) WebPEncodeRGBA(const uint8_t* rgba,
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int width, int height, int stride,
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float quality_factor, uint8_t** output);
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WEBP_EXTERN(size_t) WebPEncodeBGRA(const uint8_t* bgra,
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int width, int height, int stride,
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float quality_factor, uint8_t** output);
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//------------------------------------------------------------------------------
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// Coding parameters
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typedef struct {
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float quality; // between 0 (smallest file) and 100 (biggest)
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int target_size; // if non-zero, set the desired target size in bytes.
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// Takes precedence over the 'compression' parameter.
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float target_PSNR; // if non-zero, specifies the minimal distortion to
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// try to achieve. Takes precedence over target_size.
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int method; // quality/speed trade-off (0=fast, 6=slower-better)
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int segments; // maximum number of segments to use, in [1..4]
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int sns_strength; // Spatial Noise Shaping. 0=off, 100=maximum.
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int filter_strength; // range: [0 = off .. 100 = strongest]
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int filter_sharpness; // range: [0 = off .. 7 = least sharp]
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int filter_type; // filtering type: 0 = simple, 1 = strong
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// (only used if filter_strength > 0 or autofilter > 0)
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int autofilter; // Auto adjust filter's strength [0 = off, 1 = on]
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int pass; // number of entropy-analysis passes (in [1..10]).
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int show_compressed; // if true, export the compressed picture back.
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// In-loop filtering is not applied.
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int preprocessing; // preprocessing filter (0=none, 1=segment-smooth)
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int partitions; // log2(number of token partitions) in [0..3]
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// Default is set to 0 for easier progressive decoding.
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int partition_limit; // quality degradation allowed to fit the 512k limit on
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// prediction modes coding (0=no degradation, 100=full)
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int alpha_compression; // Algorithm for encoding the alpha plane (0 = none,
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// 1 = backward reference counts encoded with
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// arithmetic encoder). Default is 1.
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int alpha_filtering; // Predictive filtering method for alpha plane.
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// 0: none, 1: fast, 2: best. Default if 1.
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int alpha_quality; // Between 0 (smallest size) and 100 (lossless).
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// Default is 100.
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} WebPConfig;
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// Enumerate some predefined settings for WebPConfig, depending on the type
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// of source picture. These presets are used when calling WebPConfigPreset().
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typedef enum {
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WEBP_PRESET_DEFAULT = 0, // default preset.
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WEBP_PRESET_PICTURE, // digital picture, like portrait, inner shot
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WEBP_PRESET_PHOTO, // outdoor photograph, with natural lighting
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WEBP_PRESET_DRAWING, // hand or line drawing, with high-contrast details
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WEBP_PRESET_ICON, // small-sized colorful images
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WEBP_PRESET_TEXT // text-like
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} WebPPreset;
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// Internal, version-checked, entry point
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WEBP_EXTERN(int) WebPConfigInitInternal(
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WebPConfig* const, WebPPreset, float, int);
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// Should always be called, to initialize a fresh WebPConfig structure before
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// modification. Returns 0 in case of version mismatch. WebPConfigInit() must
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// have succeeded before using the 'config' object.
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static WEBP_INLINE int WebPConfigInit(WebPConfig* const config) {
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return WebPConfigInitInternal(config, WEBP_PRESET_DEFAULT, 75.f,
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WEBP_ENCODER_ABI_VERSION);
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}
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// This function will initialize the configuration according to a predefined
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// set of parameters (referred to by 'preset') and a given quality factor.
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// This function can be called as a replacement to WebPConfigInit(). Will
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// return 0 in case of error.
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static WEBP_INLINE int WebPConfigPreset(WebPConfig* const config,
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WebPPreset preset, float quality) {
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return WebPConfigInitInternal(config, preset, quality,
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WEBP_ENCODER_ABI_VERSION);
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}
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// Returns 1 if all parameters are in valid range and the configuration is OK.
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WEBP_EXTERN(int) WebPValidateConfig(const WebPConfig* const config);
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//------------------------------------------------------------------------------
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// Input / Output
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typedef struct WebPPicture WebPPicture; // main structure for I/O
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// non-essential structure for storing auxiliary statistics
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typedef struct {
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float PSNR[4]; // peak-signal-to-noise ratio for Y/U/V/All
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int coded_size; // final size
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int block_count[3]; // number of intra4/intra16/skipped macroblocks
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int header_bytes[2]; // approximate number of bytes spent for header
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// and mode-partition #0
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int residual_bytes[3][4]; // approximate number of bytes spent for
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// DC/AC/uv coefficients for each (0..3) segments.
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int segment_size[4]; // number of macroblocks in each segments
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int segment_quant[4]; // quantizer values for each segments
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int segment_level[4]; // filtering strength for each segments [0..63]
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int alpha_data_size; // size of the transparency data
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int layer_data_size; // size of the enhancement layer data
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void* user_data; // this field is free to be set to any value and
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// used during callbacks (like progress-report e.g.).
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} WebPAuxStats;
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// Signature for output function. Should return 1 if writing was successful.
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// data/data_size is the segment of data to write, and 'picture' is for
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// reference (and so one can make use of picture->custom_ptr).
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typedef int (*WebPWriterFunction)(const uint8_t* data, size_t data_size,
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const WebPPicture* const picture);
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// Progress hook, called from time to time to report progress. It can return 0
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// to request an abort of the encoding process, or 1 otherwise if all is OK.
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typedef int (*WebPProgressHook)(int percent, const WebPPicture* const picture);
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typedef enum {
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// chroma sampling
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WEBP_YUV420 = 0, // 4:2:0
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WEBP_YUV422 = 1, // 4:2:2
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WEBP_YUV444 = 2, // 4:4:4
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WEBP_YUV400 = 3, // grayscale
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WEBP_CSP_UV_MASK = 3, // bit-mask to get the UV sampling factors
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// alpha channel variants
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WEBP_YUV420A = 4,
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WEBP_YUV422A = 5,
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WEBP_YUV444A = 6,
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WEBP_YUV400A = 7, // grayscale + alpha
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WEBP_CSP_ALPHA_BIT = 4 // bit that is set if alpha is present
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} WebPEncCSP;
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// Encoding error conditions.
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typedef enum {
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VP8_ENC_OK = 0,
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VP8_ENC_ERROR_OUT_OF_MEMORY, // memory error allocating objects
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VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY, // memory error while flushing bits
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VP8_ENC_ERROR_NULL_PARAMETER, // a pointer parameter is NULL
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VP8_ENC_ERROR_INVALID_CONFIGURATION, // configuration is invalid
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VP8_ENC_ERROR_BAD_DIMENSION, // picture has invalid width/height
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VP8_ENC_ERROR_PARTITION0_OVERFLOW, // partition is bigger than 512k
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VP8_ENC_ERROR_PARTITION_OVERFLOW, // partition is bigger than 16M
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VP8_ENC_ERROR_BAD_WRITE, // error while flushing bytes
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VP8_ENC_ERROR_FILE_TOO_BIG, // file is bigger than 4G
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VP8_ENC_ERROR_USER_ABORT, // abort request by user
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VP8_ENC_ERROR_LAST // list terminator. always last.
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} WebPEncodingError;
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// maximum width/height allowed (inclusive), in pixels
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#define WEBP_MAX_DIMENSION 16383
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struct WebPPicture {
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// input
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WebPEncCSP colorspace; // colorspace: should be YUV420 for now (=Y'CbCr).
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int width, height; // dimensions (less or equal to WEBP_MAX_DIMENSION)
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uint8_t *y, *u, *v; // pointers to luma/chroma planes.
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int y_stride, uv_stride; // luma/chroma strides.
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uint8_t *a; // pointer to the alpha plane
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int a_stride; // stride of the alpha plane
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// output
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WebPWriterFunction writer; // can be NULL
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void* custom_ptr; // can be used by the writer.
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// map for extra information
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int extra_info_type; // 1: intra type, 2: segment, 3: quant
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// 4: intra-16 prediction mode,
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// 5: chroma prediction mode,
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// 6: bit cost, 7: distortion
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uint8_t* extra_info; // if not NULL, points to an array of size
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// ((width + 15) / 16) * ((height + 15) / 16) that
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// will be filled with a macroblock map, depending
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// on extra_info_type.
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// where to store statistics, if not NULL:
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WebPAuxStats* stats;
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// original samples (for non-YUV420 modes)
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uint8_t *u0, *v0;
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int uv0_stride;
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WebPEncodingError error_code; // error code in case of problem.
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WebPProgressHook progress_hook; // if not NULL, called while encoding.
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};
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// Internal, version-checked, entry point
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WEBP_EXTERN(int) WebPPictureInitInternal(WebPPicture* const, int);
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// Should always be called, to initialize the structure. Returns 0 in case of
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// version mismatch. WebPPictureInit() must have succeeded before using the
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// 'picture' object.
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static WEBP_INLINE int WebPPictureInit(WebPPicture* const picture) {
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return WebPPictureInitInternal(picture, WEBP_ENCODER_ABI_VERSION);
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}
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//------------------------------------------------------------------------------
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// WebPPicture utils
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// Convenience allocation / deallocation based on picture->width/height:
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// Allocate y/u/v buffers as per colorspace/width/height specification.
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// Note! This function will free the previous buffer if needed.
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// Returns 0 in case of memory error.
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WEBP_EXTERN(int) WebPPictureAlloc(WebPPicture* const picture);
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// Release memory allocated by WebPPictureAlloc() or WebPPictureImport*()
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// Note that this function does _not_ free the memory pointed to by 'picture'.
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WEBP_EXTERN(void) WebPPictureFree(WebPPicture* const picture);
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// Copy the pixels of *src into *dst, using WebPPictureAlloc.
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// Returns 0 in case of memory allocation error.
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WEBP_EXTERN(int) WebPPictureCopy(const WebPPicture* const src,
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WebPPicture* const dst);
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// self-crops a picture to the rectangle defined by top/left/width/height.
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// Returns 0 in case of memory allocation error, or if the rectangle is
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// outside of the source picture.
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WEBP_EXTERN(int) WebPPictureCrop(WebPPicture* const picture,
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int left, int top, int width, int height);
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// Rescale a picture to new dimension width x height.
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// Now gamma correction is applied.
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// Returns false in case of error (invalid parameter or insufficient memory).
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WEBP_EXTERN(int) WebPPictureRescale(WebPPicture* const pic,
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int width, int height);
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// Colorspace conversion function to import RGB samples.
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// Previous buffer will be free'd, if any.
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// *rgb buffer should have a size of at least height * rgb_stride.
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// Returns 0 in case of memory error.
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WEBP_EXTERN(int) WebPPictureImportRGB(
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WebPPicture* const picture, const uint8_t* const rgb, int rgb_stride);
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// Same, but for RGBA buffer
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WEBP_EXTERN(int) WebPPictureImportRGBA(
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WebPPicture* const picture, const uint8_t* const rgba, int rgba_stride);
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// Variant of the above, but taking BGR(A) input:
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WEBP_EXTERN(int) WebPPictureImportBGR(
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WebPPicture* const picture, const uint8_t* const bgr, int bgr_stride);
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WEBP_EXTERN(int) WebPPictureImportBGRA(
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WebPPicture* const picture, const uint8_t* const bgra, int bgra_stride);
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// Helper function: given a width x height plane of YUV(A) samples
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// (with stride 'stride'), clean-up the YUV samples under fully transparent
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// area, to help compressibility (no guarantee, though).
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WEBP_EXTERN(void) WebPCleanupTransparentArea(WebPPicture* const picture);
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//------------------------------------------------------------------------------
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// Main call
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// Main encoding call, after config and picture have been initialized.
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// 'picture' must be less than 16384x16384 in dimension (cf WEBP_MAX_DIMENSION),
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// and the 'config' object must be a valid one.
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// Returns false in case of error, true otherwise.
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// In case of error, picture->error_code is updated accordingly.
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WEBP_EXTERN(int) WebPEncode(
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const WebPConfig* const config, WebPPicture* const picture);
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//------------------------------------------------------------------------------
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#if defined(__cplusplus) || defined(c_plusplus)
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} // extern "C"
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#endif
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#endif /* WEBP_WEBP_ENCODE_H_ */
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