WebP-encode.h详解

// Copyright 2011 Google Inc. All Rights Reserved.

//

// Use of this source code is governed by a BSD-style license

// that can be found in the COPYING file in the root of the source

// tree. An additional intellectual property rights grant can be found

// in the file PATENTS. All contributing project authors may

// be found in the AUTHORS file in the root of the source tree.

// —————————————————————————–

//

//   WebP encoder: main interface

//

// Author: Skal (pascal.massimino@gmail.com)

#ifndef WEBP_WEBP_ENCODE_H_

#define WEBP_WEBP_ENCODE_H_

#include “./types.h”

#ifdef __cplusplus

extern “C” {

#endif

#define WEBP_ENCODER_ABI_VERSION 0x020e    // MAJOR(8b) + MINOR(8b)

// Note: forward declaring enumerations is not allowed in (strict) C and C++,

// the types are left here for reference.

// typedef enum WebPImageHint WebPImageHint;

// typedef enum WebPEncCSP WebPEncCSP;

// typedef enum WebPPreset WebPPreset;

// typedef enum WebPEncodingError WebPEncodingError;

typedef struct WebPConfig WebPConfig;

typedef struct WebPPicture WebPPicture;   // main structure for I/O

typedef struct WebPAuxStats WebPAuxStats;

typedef struct WebPMemoryWriter WebPMemoryWriter;

// Return the encoder’s version number, packed in hexadecimal using 8bits for

// each of major/minor/revision. E.g: v2.5.7 is 0x020507.

WEBP_EXTERN int WebPGetEncoderVersion(void);

//——————————————————————————

// One-stop-shop call! No questions asked:

// 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 ‘WebPFree(*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);

WEBP_EXTERN size_t WebPEncodeBGR(const uint8_t* bgr,

                                 int width, int height, int stride,

                                 float quality_factor, uint8_t** output);

WEBP_EXTERN size_t WebPEncodeRGBA(const uint8_t* rgba,

                                  int width, int height, int stride,

                                  float quality_factor, uint8_t** output);

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);

// Releases memory returned by the WebPEncode*() functions above.

WEBP_EXTERN void WebPFree(void* ptr);

//——————————————————————————

// Coding parameters

// Image characteristics hint for the underlying encoder.

typedef enum WebPImageHint {

  WEBP_HINT_DEFAULT = 0,  // default preset.

  WEBP_HINT_PICTURE,      // digital picture, like portrait, inner shot

  WEBP_HINT_PHOTO,        // outdoor photograph, with natural lighting

  WEBP_HINT_GRAPH,        // Discrete tone image (graph, map-tile etc).

  WEBP_HINT_LAST

} WebPImageHint;

// Compression parameters.

struct WebPConfig {

  int lossless;           // Lossless encoding (0=lossy(default), 1=lossless).

  float quality;          // between 0 and 100. For lossy, 0 gives the smallest

                          // size and 100 the largest. For lossless, this

                          // parameter is the amount of effort put into the

                          // compression: 0 is the fastest but gives larger

                          // files compared to the slowest, but best, 100.

  int method;             // quality/speed trade-off (0=fast, 6=slower-better)

  WebPImageHint image_hint;  // Hint for image type (lossless only for now).

  int target_size;        // if non-zero, set the desired target size in bytes.

                          // Takes precedence over the ‘compression’ parameter.

  float target_PSNR;      // if non-zero, specifies the minimal distortion to

                          // try to achieve. Takes precedence over target_size.

  int segments;           // maximum number of segments to use, in [1..4]

  int sns_strength;       // Spatial Noise Shaping. 0=off, 100=maximum.

  int filter_strength;    // range: [0 = off .. 100 = strongest]

  int filter_sharpness;   // range: [0 = off .. 7 = least sharp]

  int filter_type;        // filtering type: 0 = simple, 1 = strong (only used

                          // if filter_strength > 0 or autofilter > 0)

  int autofilter;         // Auto adjust filter’s strength [0 = off, 1 = on]

  int alpha_compression;  // Algorithm for encoding the alpha plane (0 = none,

                          // 1 = compressed with WebP lossless). Default is 1.

  int alpha_filtering;    // Predictive filtering method for alpha plane.

                          //  0: none, 1: fast, 2: best. Default if 1.

  int alpha_quality;      // Between 0 (smallest size) and 100 (lossless).

                          // Default is 100.

  int pass;               // number of entropy-analysis passes (in [1..10]).

  int show_compressed;    // if true, export the compressed picture back.

                          // In-loop filtering is not applied.

  int preprocessing;      // preprocessing filter:

                          // 0=none, 1=segment-smooth, 2=pseudo-random dithering

  int partitions;         // log2(number of token partitions) in [0..3]. Default

                          // is set to 0 for easier progressive decoding.

  int partition_limit;    // quality degradation allowed to fit the 512k limit

                          // on prediction modes coding (0: no degradation,

                          // 100: maximum possible degradation).

  int emulate_jpeg_size;  // If true, compression parameters will be remapped

                          // to better match the expected output size from

                          // JPEG compression. Generally, the output size will

                          // be similar but the degradation will be lower.

  int thread_level;       // If non-zero, try and use multi-threaded encoding.

  int low_memory;         // If set, reduce memory usage (but increase CPU use).

  int near_lossless;      // Near lossless encoding [0 = max loss .. 100 = off

                          // (default)].

  int exact;              // if non-zero, preserve the exact RGB values under

                          // transparent area. Otherwise, discard this invisible

                          // RGB information for better compression. The default

                          // value is 0.

  int use_delta_palette;  // reserved for future lossless feature

  int use_sharp_yuv;      // if needed, use sharp (and slow) RGB->YUV conversion

  uint32_t pad[2];        // padding for later use

};

// Enumerate some predefined settings for WebPConfig, depending on the type

// of source picture. These presets are used when calling WebPConfigPreset().

typedef enum WebPPreset {

  WEBP_PRESET_DEFAULT = 0,  // default preset.

  WEBP_PRESET_PICTURE,      // digital picture, like portrait, inner shot

  WEBP_PRESET_PHOTO,        // outdoor photograph, with natural lighting

  WEBP_PRESET_DRAWING,      // hand or line drawing, with high-contrast details

  WEBP_PRESET_ICON,         // small-sized colorful images

  WEBP_PRESET_TEXT          // text-like

} WebPPreset;

// Internal, version-checked, entry point

WEBP_EXTERN int WebPConfigInitInternal(WebPConfig*, WebPPreset, float, int);

// Should always be called, to initialize a fresh WebPConfig structure before

// modification. Returns false in case of version mismatch. WebPConfigInit()

// must have succeeded before using the ‘config‘ object.

// Note that the default values are lossless=0 and quality=75.

static WEBP_INLINE int WebPConfigInit(WebPConfig* config) {

  return WebPConfigInitInternal(config, WEBP_PRESET_DEFAULT, 75.f,

                                WEBP_ENCODER_ABI_VERSION);

}

// This function will initialize the configuration according to a predefined

// set of parameters (referred to by ‘preset’) and a given quality factor.

// This function can be called as a replacement to WebPConfigInit(). Will

// return false in case of error.

static WEBP_INLINE int WebPConfigPreset(WebPConfig* config,

                                        WebPPreset preset, float quality) {

  return WebPConfigInitInternal(config, preset, quality,

                                WEBP_ENCODER_ABI_VERSION);

}

// Activate the lossless compression mode with the desired efficiency level

// between 0 (fastest, lowest compression) and 9 (slower, best compression).

// A good default level is ‘6’, providing a fair tradeoff between compression

// speed and final compressed size.

// This function will overwrite several fields from config: ‘method’, ‘quality’

// and ‘lossless‘. Returns false in case of parameter error.

WEBP_EXTERN int WebPConfigLosslessPreset(WebPConfig* config, int level);

// Returns true if ‘config‘ is non-NULL and all configuration parameters are

// within their valid ranges.

WEBP_EXTERN int WebPValidateConfig(const WebPConfig* config);

//——————————————————————————

// Input / Output

// Structure for storing auxiliary statistics.

struct WebPAuxStats {

  int coded_size;         // final size

  float PSNR[5];          // peak-signal-to-noise ratio for Y/U/V/All/Alpha

  int block_count[3];     // number of intra4/intra16/skipped macroblocks

  int header_bytes[2];    // approximate number of bytes spent for header

                          // and mode-partition #0

  int residual_bytes[3][4];  // approximate number of bytes spent for

                             // DC/AC/uv coefficients for each (0..3) segments.

  int segment_size[4];    // number of macroblocks in each segments

  int segment_quant[4];   // quantizer values for each segments

  int segment_level[4];   // filtering strength for each segments [0..63]

  int alpha_data_size;    // size of the transparency data

  int layer_data_size;    // size of the enhancement layer data

  // lossless encoder statistics

  uint32_t lossless_features;  // bit0:predictor bit1:cross-color transform

                               // bit2:subtract-green bit3:color indexing

  int histogram_bits;          // number of precision bits of histogram

  int transform_bits;          // precision bits for transform

  int cache_bits;              // number of bits for color cache lookup

  int palette_size;            // number of color in palette, if used

  int lossless_size;           // final lossless size

  int lossless_hdr_size;       // lossless header (transform, huffman etc) size

  int lossless_data_size;      // lossless image data size

  uint32_t pad[2];        // padding for later use

};

// Signature for output function. Should return true if writing was successful.

// data/data_size is the segment of data to write, and ‘picture’ is for

// reference (and so one can make use of picture->custom_ptr).

typedef int (*WebPWriterFunction)(const uint8_t* data, size_t data_size,

                                  const WebPPicture* picture);

// WebPMemoryWrite: a special WebPWriterFunction that writes to memory using

// the following WebPMemoryWriter object (to be set as a custom_ptr).

struct WebPMemoryWriter {

  uint8_t* mem;       // final buffer (of size ‘max_size’, larger than ‘size’).

  size_t   size;      // final size

  size_t   max_size;  // total capacity

  uint32_t pad[1];    // padding for later use

};

// The following must be called first before any use.

WEBP_EXTERN void WebPMemoryWriterInit(WebPMemoryWriter* writer);

// The following must be called to deallocate writer->mem memory. The ‘writer’

// object itself is not deallocated.

WEBP_EXTERN void WebPMemoryWriterClear(WebPMemoryWriter* writer);

// The custom writer to be used with WebPMemoryWriter as custom_ptr. Upon

// completion, writer.mem and writer.size will hold the coded data.

// writer.mem must be freed by calling WebPMemoryWriterClear.

WEBP_EXTERN int WebPMemoryWrite(const uint8_t* data, size_t data_size,

                                const WebPPicture* picture);

// Progress hook, called from time to time to report progress. It can return

// false to request an abort of the encoding process, or true otherwise if

// everything is OK.

typedef int (*WebPProgressHook)(int percent, const WebPPicture* picture);

// Color spaces.

typedef enum WebPEncCSP {

  // chroma sampling

  WEBP_YUV420  = 0,        // 4:2:0

  WEBP_YUV420A = 4,        // alpha channel variant

  WEBP_CSP_UV_MASK = 3,    // bit-mask to get the UV sampling factors

  WEBP_CSP_ALPHA_BIT = 4   // bit that is set if alpha is present

} WebPEncCSP;

// Encoding error conditions.

typedef enum WebPEncodingError {

  VP8_ENC_OK = 0,

  VP8_ENC_ERROR_OUT_OF_MEMORY,            // memory error allocating objects

  VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY,  // memory error while flushing bits

  VP8_ENC_ERROR_NULL_PARAMETER,           // a pointer parameter is NULL

  VP8_ENC_ERROR_INVALID_CONFIGURATION,    // configuration is invalid

  VP8_ENC_ERROR_BAD_DIMENSION,            // picture has invalid width/height

  VP8_ENC_ERROR_PARTITION0_OVERFLOW,      // partition is bigger than 512k

  VP8_ENC_ERROR_PARTITION_OVERFLOW,       // partition is bigger than 16M

  VP8_ENC_ERROR_BAD_WRITE,                // error while flushing bytes

  VP8_ENC_ERROR_FILE_TOO_BIG,             // file is bigger than 4G

  VP8_ENC_ERROR_USER_ABORT,               // abort request by user

  VP8_ENC_ERROR_LAST                      // list terminator. always last.

} WebPEncodingError;

// maximum width/height allowed (inclusive), in pixels

#define WEBP_MAX_DIMENSION 16383

// Main exchange structure (input samples, output bytes, statistics)

//主交换结构(输入样本,输出字节,统计)

struct WebPPicture {

  //   INPUT

  //////////////

  // Main flag for encoder selecting between ARGB or YUV input.

  // It is recommended to use ARGB input (*argb, argb_stride) for lossless

  // compression, and YUV input (*y, *u, *v, etc.) for lossy compression

  // since these are the respective native colorspace for these formats.

  int use_argb;

  // YUV input (mostly used for input to lossy compression)

  WebPEncCSP colorspace;     // colorspace: should be YUV420 for now (=Y’CbCr).

  int width, height;         // dimensions (less or equal to WEBP_MAX_DIMENSION)

  uint8_t *y, *u, *v;        // pointers to luma/chroma planes.

  int y_stride, uv_stride;   // luma/chroma strides.

  uint8_t* a;                // pointer to the alpha plane

  int a_stride;              // stride of the alpha plane

  uint32_t pad1[2];          // padding for later use

  // ARGB input (mostly used for input to lossless compression)

  uint32_t* argb;            // Pointer to argb (32 bit) plane.

  int argb_stride;           // This is stride in pixels units, not bytes.

  uint32_t pad2[3];          // padding for later use

  //   OUTPUT

  ///////////////

  // Byte-emission hook, to store compressed bytes as they are ready.

  WebPWriterFunction writer;  // can be NULL

  void* custom_ptr;           // can be used by the writer.

  // map for extra information (only for lossy compression mode)

  int extra_info_type;    // 1: intra type, 2: segment, 3: quant

                          // 4: intra-16 prediction mode,

                          // 5: chroma prediction mode,

                          // 6: bit cost, 7: distortion

  uint8_t* extra_info;    // if not NULL, points to an array of size

                          // ((width + 15) / 16) * ((height + 15) / 16) that

                          // will be filled with a macroblock map, depending

                          // on extra_info_type.

  //   STATS AND REPORTS

  ///////////////////////////

  // Pointer to side statistics (updated only if not NULL)

  WebPAuxStats* stats;

  // Error code for the latest error encountered during encoding

  WebPEncodingError error_code;

  // If not NULL, report progress during encoding.

  WebPProgressHook progress_hook;

  void* user_data;        // this field is free to be set to any value and

                          // used during callbacks (like progress-report e.g.).

  uint32_t pad3[3];       // padding for later use

  // Unused for now

  uint8_t *pad4, *pad5;

  uint32_t pad6[8];       // padding for later use

  // PRIVATE FIELDS

  ////////////////////

  void* memory_;          // row chunk of memory for yuva planes

  void* memory_argb_;     // and for argb too.

  void* pad7[2];          // padding for later use

};

// Internal, version-checked, entry point

WEBP_EXTERN int WebPPictureInitInternal(WebPPicture*, int);

// Should always be called, to initialize the structure. Returns false in case

// of version mismatch. WebPPictureInit() must have succeeded before using the

// ‘picture’ object.

// Note that, by default, use_argb is false and colorspace is WEBP_YUV420.

static WEBP_INLINE int WebPPictureInit(WebPPicture* picture) {

  return WebPPictureInitInternal(picture, WEBP_ENCODER_ABI_VERSION);

}

//——————————————————————————

// WebPPicture utils

// Convenience allocation / deallocation based on picture->width/height:

// Allocate y/u/v buffers as per colorspace/width/height specification.

// Note! This function will free the previous buffer if needed.

// Returns false in case of memory error.

WEBP_EXTERN int WebPPictureAlloc(WebPPicture* picture);

// Release the memory allocated by WebPPictureAlloc() or WebPPictureImport*().

// Note that this function does _not_ free the memory used by the ‘picture’

// object itself.

// Besides memory (which is reclaimed) all other fields of ‘picture’ are

// preserved.

WEBP_EXTERN void WebPPictureFree(WebPPicture* picture);

// Copy the pixels of *src into *dst, using WebPPictureAlloc. Upon return, *dst

// will fully own the copied pixels (this is not a view). The ‘dst‘ picture need

// not be initialized as its content is overwritten.

// Returns false in case of memory allocation error.

WEBP_EXTERN int WebPPictureCopy(const WebPPicture* src, WebPPicture* dst);

// Compute the single distortion for packed planes of samples.

// ‘src‘ will be compared to ‘ref‘, and the raw distortion stored into

// ‘*distortion’. The refined metric (log(MSE), log(1 – ssim),…’ will be

// stored in ‘*result’.

// ‘x_step’ is the horizontal stride (in bytes) between samples.

// ‘src/ref_stride’ is the byte distance between rows.

// Returns false in case of error (bad parameter, memory allocation error, …).

WEBP_EXTERN int WebPPlaneDistortion(const uint8_t* src, size_t src_stride,

                                    const uint8_t* ref, size_t ref_stride,

                                    int width, int height,

                                    size_t x_step,

                                    int type,   // 0 = PSNR, 1 = SSIM, 2 = LSIM

                                    float* distortion, float* result);

// Compute PSNR, SSIM or LSIM distortion metric between two pictures. Results

// are in dB, stored in result[] in the B/G/R/A/All order. The distortion is

// always performed using ARGB samples. Hence if the input is YUV(A), the

// picture will be internally converted to ARGB (just for the measurement).

// Warning: this function is rather CPU-intensive.

WEBP_EXTERN int WebPPictureDistortion(

    const WebPPicture* src, const WebPPicture* ref,

    int metric_type,           // 0 = PSNR, 1 = SSIM, 2 = LSIM

    float result[5]);

// self-crops a picture to the rectangle defined by top/left/width/height.

// Returns false in case of memory allocation error, or if the rectangle is

// outside of the source picture.

// The rectangle for the view is defined by the top-left corner pixel

// coordinates (left, top) as well as its width and height. This rectangle

// must be fully be comprised inside the ‘src‘ source picture. If the source

// picture uses the YUV420 colorspace, the top and left coordinates will be

// snapped to even values.

WEBP_EXTERN int WebPPictureCrop(WebPPicture* picture,

                                int left, int top, int width, int height);

// Extracts a view from ‘src‘ picture into ‘dst‘. The rectangle for the view

// is defined by the top-left corner pixel coordinates (left, top) as well

// as its width and height. This rectangle must be fully be comprised inside

// the ‘src‘ source picture. If the source picture uses the YUV420 colorspace,

// the top and left coordinates will be snapped to even values.

// Picture ‘src‘ must out-live ‘dst‘ picture. Self-extraction of view is allowed

// (‘src‘ equal to ‘dst‘) as a mean of fast-cropping (but note that doing so,

// the original dimension will be lost). Picture ‘dst‘ need not be initialized

// with WebPPictureInit() if it is different from ‘src‘, since its content will

// be overwritten.

// Returns false in case of memory allocation error or invalid parameters.

WEBP_EXTERN int WebPPictureView(const WebPPicture* src,

                                int left, int top, int width, int height,

                                WebPPicture* dst);

// Returns true if the ‘picture’ is actually a view and therefore does

// not own the memory for pixels.

WEBP_EXTERN int WebPPictureIsView(const WebPPicture* picture);

// Rescale a picture to new dimension width x height.

// If either ‘width’ or ‘height’ (but not both) is 0 the corresponding

// dimension will be calculated preserving the aspect ratio.

// No gamma correction is applied.

// Returns false in case of error (invalid parameter or insufficient memory).

WEBP_EXTERN int WebPPictureRescale(WebPPicture* pic, int width, int height);

// Colorspace conversion function to import RGB samples.

// Previous buffer will be free’d, if any.

// *rgb buffer should have a size of at least height * rgb_stride.

// Returns false in case of memory error.

WEBP_EXTERN int WebPPictureImportRGB(

    WebPPicture* picture, const uint8_t* rgb, int rgb_stride);

// Same, but for RGBA buffer.

WEBP_EXTERN int WebPPictureImportRGBA(

    WebPPicture* picture, const uint8_t* rgba, int rgba_stride);

// Same, but for RGBA buffer. Imports the RGB direct from the 32-bit format

// input buffer ignoring the alpha channel. Avoids needing to copy the data

// to a temporary 24-bit RGB buffer to import the RGB only.

WEBP_EXTERN int WebPPictureImportRGBX(

    WebPPicture* picture, const uint8_t* rgbx, int rgbx_stride);

// Variants of the above, but taking BGR(A|X) input.

WEBP_EXTERN int WebPPictureImportBGR(

    WebPPicture* picture, const uint8_t* bgr, int bgr_stride);

WEBP_EXTERN int WebPPictureImportBGRA(

    WebPPicture* picture, const uint8_t* bgra, int bgra_stride);

WEBP_EXTERN int WebPPictureImportBGRX(

    WebPPicture* picture, const uint8_t* bgrx, int bgrx_stride);

// Converts picture->argb data to the YUV420A format. The ‘colorspace

// parameter is deprecated and should be equal to WEBP_YUV420.

// Upon return, picture->use_argb is set to false. The presence of real

// non-opaque transparent values is detected, and ‘colorspace‘ will be

// adjusted accordingly. Note that this method is lossy.

// Returns false in case of error.

WEBP_EXTERN int WebPPictureARGBToYUVA(WebPPicture* picture,

                                      WebPEncCSP /*colorspace = WEBP_YUV420*/);

// Same as WebPPictureARGBToYUVA(), but the conversion is done using

// pseudo-random dithering with a strength ‘dithering‘ between

// 0.0 (no dithering) and 1.0 (maximum dithering). This is useful

// for photographic picture.

WEBP_EXTERN int WebPPictureARGBToYUVADithered(

    WebPPicture* picture, WebPEncCSP colorspace, float dithering);

// Performs ‘sharp’ RGBA->YUVA420 downsampling and colorspace conversion.

// Downsampling is handled with extra care in case of color clipping. This

// method is roughly 2x slower than WebPPictureARGBToYUVA() but produces better

// and sharper YUV representation.

// Returns false in case of error.

WEBP_EXTERN int WebPPictureSharpARGBToYUVA(WebPPicture* picture);

// kept for backward compatibility:

WEBP_EXTERN int WebPPictureSmartARGBToYUVA(WebPPicture* picture);

// Converts picture->yuv to picture->argb and sets picture->use_argb to true.

// The input format must be YUV_420 or YUV_420A. The conversion from YUV420 to

// ARGB incurs a small loss too.

// Note that the use of this colorspace is discouraged if one has access to the

// raw ARGB samples, since using YUV420 is comparatively lossy.

// Returns false in case of error.

WEBP_EXTERN int WebPPictureYUVAToARGB(WebPPicture* picture);

// Helper function: given a width x height plane of RGBA or YUV(A) samples

// clean-up or smoothen the YUV or RGB samples under fully transparent area,

// to help compressibility (no guarantee, though).

WEBP_EXTERN void WebPCleanupTransparentArea(WebPPicture* picture);

// Scan the picture ‘picture’ for the presence of non fully opaque alpha values.

// Returns true in such case. Otherwise returns false (indicating that the

// alpha plane can be ignored altogether e.g.).

WEBP_EXTERN int WebPPictureHasTransparency(const WebPPicture* picture);

// Remove the transparency information (if present) by blending the color with

// the background color ‘background_rgb’ (specified as 24bit RGB triplet).

// After this call, all alpha values are reset to 0xff.

WEBP_EXTERN void WebPBlendAlpha(WebPPicture* pic, uint32_t background_rgb);

//——————————————————————————

// Main call

// Main encoding call, after config and picture have been initialized.

// ‘picture’ must be less than 16384×16384 in dimension (cf WEBP_MAX_DIMENSION),

// and the ‘config‘ object must be a valid one.

// Returns false in case of error, true otherwise.

// In case of error, picture->error_code is updated accordingly.

// ‘picture’ can hold the source samples in both YUV(A) or ARGB input, depending

// on the value of ‘picture->use_argb’. It is highly recommended to use

// the former for lossy encoding, and the latter for lossless encoding

// (when config.lossless is true). Automatic conversion from one format to

// another is provided but they both incur some loss.

WEBP_EXTERN int WebPEncode(const WebPConfig* config, WebPPicture* picture);

//——————————————————————————

#ifdef __cplusplus

}    // extern “C”

#endif

#endif  /* WEBP_WEBP_ENCODE_H_ */

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