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| 1 | +// Copyright 2022 Google Inc. All Rights Reserved. |
| 2 | +// |
| 3 | +// Use of this source code is governed by a BSD-style license |
| 4 | +// that can be found in the COPYING file in the root of the source |
| 5 | +// tree. An additional intellectual property rights grant can be found |
| 6 | +// in the file PATENTS. All contributing project authors may |
| 7 | +// be found in the AUTHORS file in the root of the source tree. |
| 8 | +// ----------------------------------------------------------------------------- |
| 9 | +// |
| 10 | +// Sharp RGB to YUV conversion. |
| 11 | + |
| 12 | +#ifndef WEBP_SHARPYUV_SHARPYUV_H_ |
| 13 | +#define WEBP_SHARPYUV_SHARPYUV_H_ |
| 14 | + |
| 15 | +#ifdef __cplusplus |
| 16 | +extern "C" { |
| 17 | +#endif |
| 18 | + |
| 19 | +#ifndef SHARPYUV_EXTERN |
| 20 | +#ifdef WEBP_EXTERN |
| 21 | +#define SHARPYUV_EXTERN WEBP_EXTERN |
| 22 | +#else |
| 23 | +// This explicitly marks library functions and allows for changing the |
| 24 | +// signature for e.g., Windows DLL builds. |
| 25 | +#if defined(_WIN32) && defined(WEBP_DLL) |
| 26 | +#define SHARPYUV_EXTERN __declspec(dllexport) |
| 27 | +#elif defined(__GNUC__) && __GNUC__ >= 4 |
| 28 | +#define SHARPYUV_EXTERN extern __attribute__((visibility("default"))) |
| 29 | +#else |
| 30 | +#define SHARPYUV_EXTERN extern |
| 31 | +#endif /* defined(_WIN32) && defined(WEBP_DLL) */ |
| 32 | +#endif /* WEBP_EXTERN */ |
| 33 | +#endif /* SHARPYUV_EXTERN */ |
| 34 | + |
| 35 | +#ifndef SHARPYUV_INLINE |
| 36 | +#ifdef WEBP_INLINE |
| 37 | +#define SHARPYUV_INLINE WEBP_INLINE |
| 38 | +#else |
| 39 | +#ifndef _MSC_VER |
| 40 | +#if defined(__cplusplus) || !defined(__STRICT_ANSI__) || \ |
| 41 | + (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) |
| 42 | +#define SHARPYUV_INLINE inline |
| 43 | +#else |
| 44 | +#define SHARPYUV_INLINE |
| 45 | +#endif |
| 46 | +#else |
| 47 | +#define SHARPYUV_INLINE __forceinline |
| 48 | +#endif /* _MSC_VER */ |
| 49 | +#endif /* WEBP_INLINE */ |
| 50 | +#endif /* SHARPYUV_INLINE */ |
| 51 | + |
| 52 | +// SharpYUV API version following the convention from semver.org |
| 53 | +#define SHARPYUV_VERSION_MAJOR 0 |
| 54 | +#define SHARPYUV_VERSION_MINOR 4 |
| 55 | +#define SHARPYUV_VERSION_PATCH 0 |
| 56 | +// Version as a uint32_t. The major number is the high 8 bits. |
| 57 | +// The minor number is the middle 8 bits. The patch number is the low 16 bits. |
| 58 | +#define SHARPYUV_MAKE_VERSION(MAJOR, MINOR, PATCH) \ |
| 59 | + (((MAJOR) << 24) | ((MINOR) << 16) | (PATCH)) |
| 60 | +#define SHARPYUV_VERSION \ |
| 61 | + SHARPYUV_MAKE_VERSION(SHARPYUV_VERSION_MAJOR, SHARPYUV_VERSION_MINOR, \ |
| 62 | + SHARPYUV_VERSION_PATCH) |
| 63 | + |
| 64 | +// Returns the library's version number, packed in hexadecimal. See |
| 65 | +// SHARPYUV_VERSION. |
| 66 | +SHARPYUV_EXTERN int SharpYuvGetVersion(void); |
| 67 | + |
| 68 | +// RGB to YUV conversion matrix, in 16 bit fixed point. |
| 69 | +// y = rgb_to_y[0] * r + rgb_to_y[1] * g + rgb_to_y[2] * b + rgb_to_y[3] |
| 70 | +// u = rgb_to_u[0] * r + rgb_to_u[1] * g + rgb_to_u[2] * b + rgb_to_u[3] |
| 71 | +// v = rgb_to_v[0] * r + rgb_to_v[1] * g + rgb_to_v[2] * b + rgb_to_v[3] |
| 72 | +// Then y, u and v values are divided by 1<<16 and rounded. |
| 73 | +typedef struct { |
| 74 | + int rgb_to_y[4]; |
| 75 | + int rgb_to_u[4]; |
| 76 | + int rgb_to_v[4]; |
| 77 | +} SharpYuvConversionMatrix; |
| 78 | + |
| 79 | +typedef struct SharpYuvOptions SharpYuvOptions; |
| 80 | + |
| 81 | +// Enums for transfer functions, as defined in H.273, |
| 82 | +// https://www.itu.int/rec/T-REC-H.273-202107-I/en |
| 83 | +typedef enum SharpYuvTransferFunctionType { |
| 84 | + // 0 is reserved |
| 85 | + kSharpYuvTransferFunctionBt709 = 1, |
| 86 | + // 2 is unspecified |
| 87 | + // 3 is reserved |
| 88 | + kSharpYuvTransferFunctionBt470M = 4, |
| 89 | + kSharpYuvTransferFunctionBt470Bg = 5, |
| 90 | + kSharpYuvTransferFunctionBt601 = 6, |
| 91 | + kSharpYuvTransferFunctionSmpte240 = 7, |
| 92 | + kSharpYuvTransferFunctionLinear = 8, |
| 93 | + kSharpYuvTransferFunctionLog100 = 9, |
| 94 | + kSharpYuvTransferFunctionLog100_Sqrt10 = 10, |
| 95 | + kSharpYuvTransferFunctionIec61966 = 11, |
| 96 | + kSharpYuvTransferFunctionBt1361 = 12, |
| 97 | + kSharpYuvTransferFunctionSrgb = 13, |
| 98 | + kSharpYuvTransferFunctionBt2020_10Bit = 14, |
| 99 | + kSharpYuvTransferFunctionBt2020_12Bit = 15, |
| 100 | + kSharpYuvTransferFunctionSmpte2084 = 16, // PQ |
| 101 | + kSharpYuvTransferFunctionSmpte428 = 17, |
| 102 | + kSharpYuvTransferFunctionHlg = 18, |
| 103 | + kSharpYuvTransferFunctionNum |
| 104 | +} SharpYuvTransferFunctionType; |
| 105 | + |
| 106 | +// Converts RGB to YUV420 using a downsampling algorithm that minimizes |
| 107 | +// artefacts caused by chroma subsampling. |
| 108 | +// This is slower than standard downsampling (averaging of 4 UV values). |
| 109 | +// Assumes that the image will be upsampled using a bilinear filter. If nearest |
| 110 | +// neighbor is used instead, the upsampled image might look worse than with |
| 111 | +// standard downsampling. |
| 112 | +// r_ptr, g_ptr, b_ptr: pointers to the source r, g and b channels. Should point |
| 113 | +// to uint8_t buffers if rgb_bit_depth is 8, or uint16_t buffers otherwise. |
| 114 | +// rgb_step: distance in bytes between two horizontally adjacent pixels on the |
| 115 | +// r, g and b channels. If rgb_bit_depth is > 8, it should be a |
| 116 | +// multiple of 2. |
| 117 | +// rgb_stride: distance in bytes between two vertically adjacent pixels on the |
| 118 | +// r, g, and b channels. If rgb_bit_depth is > 8, it should be a |
| 119 | +// multiple of 2. |
| 120 | +// rgb_bit_depth: number of bits for each r/g/b value. One of: 8, 10, 12, 16. |
| 121 | +// Note: 16 bit input is truncated to 14 bits before conversion to yuv. |
| 122 | +// yuv_bit_depth: number of bits for each y/u/v value. One of: 8, 10, 12. |
| 123 | +// y_ptr, u_ptr, v_ptr: pointers to the destination y, u and v channels. Should |
| 124 | +// point to uint8_t buffers if yuv_bit_depth is 8, or uint16_t buffers |
| 125 | +// otherwise. |
| 126 | +// y_stride, u_stride, v_stride: distance in bytes between two vertically |
| 127 | +// adjacent pixels on the y, u and v channels. If yuv_bit_depth > 8, they |
| 128 | +// should be multiples of 2. |
| 129 | +// width, height: width and height of the image in pixels |
| 130 | +// This function calls SharpYuvConvertWithOptions with a default transfer |
| 131 | +// function of kSharpYuvTransferFunctionSrgb. |
| 132 | +SHARPYUV_EXTERN int SharpYuvConvert(const void* r_ptr, const void* g_ptr, |
| 133 | + const void* b_ptr, int rgb_step, |
| 134 | + int rgb_stride, int rgb_bit_depth, |
| 135 | + void* y_ptr, int y_stride, void* u_ptr, |
| 136 | + int u_stride, void* v_ptr, int v_stride, |
| 137 | + int yuv_bit_depth, int width, int height, |
| 138 | + const SharpYuvConversionMatrix* yuv_matrix); |
| 139 | + |
| 140 | +struct SharpYuvOptions { |
| 141 | + // This matrix cannot be NULL and can be initialized by |
| 142 | + // SharpYuvComputeConversionMatrix. |
| 143 | + const SharpYuvConversionMatrix* yuv_matrix; |
| 144 | + SharpYuvTransferFunctionType transfer_type; |
| 145 | +}; |
| 146 | + |
| 147 | +// Internal, version-checked, entry point |
| 148 | +SHARPYUV_EXTERN int SharpYuvOptionsInitInternal(const SharpYuvConversionMatrix*, |
| 149 | + SharpYuvOptions*, int); |
| 150 | + |
| 151 | +// Should always be called, to initialize a fresh SharpYuvOptions |
| 152 | +// structure before modification. SharpYuvOptionsInit() must have succeeded |
| 153 | +// before using the 'options' object. |
| 154 | +static SHARPYUV_INLINE int SharpYuvOptionsInit( |
| 155 | + const SharpYuvConversionMatrix* yuv_matrix, SharpYuvOptions* options) { |
| 156 | + return SharpYuvOptionsInitInternal(yuv_matrix, options, SHARPYUV_VERSION); |
| 157 | +} |
| 158 | + |
| 159 | +SHARPYUV_EXTERN int SharpYuvConvertWithOptions( |
| 160 | + const void* r_ptr, const void* g_ptr, const void* b_ptr, int rgb_step, |
| 161 | + int rgb_stride, int rgb_bit_depth, void* y_ptr, int y_stride, void* u_ptr, |
| 162 | + int u_stride, void* v_ptr, int v_stride, int yuv_bit_depth, int width, |
| 163 | + int height, const SharpYuvOptions* options); |
| 164 | + |
| 165 | +// TODO(b/194336375): Add YUV444 to YUV420 conversion. Maybe also add 422 |
| 166 | +// support (it's rarely used in practice, especially for images). |
| 167 | + |
| 168 | +#ifdef __cplusplus |
| 169 | +} // extern "C" |
| 170 | +#endif |
| 171 | + |
| 172 | +#endif // WEBP_SHARPYUV_SHARPYUV_H_ |
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