Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 546 insertions, 0 deletions

diff --git a/media/libwebp/src/webp/encode.h b/media/libwebp/src/webp/encode.h
new file mode 100644
index 0000000000..655166e7d4
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+++ b/media/libwebp/src/webp/encode.h
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+// 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 0x020f    // 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.
+// Note these functions, like the lossy versions, use the library's default
+// settings. For lossless this means 'exact' is disabled. RGB values in
+// transparent areas will be modified to improve compression. To avoid this,
+// use WebPEncode() and set WebPConfig::exact to 1.
+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
+
+// 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)
+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 16384x16384 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_