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Editing: encode.h
// 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) 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_ */
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