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172 lines
7.1 KiB
172 lines
7.1 KiB
// Copyright 2022 Google Inc. All Rights Reserved. |
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// |
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// Use of this source code is governed by a BSD-style license |
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// that can be found in the COPYING file in the root of the source |
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// tree. An additional intellectual property rights grant can be found |
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// in the file PATENTS. All contributing project authors may |
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// be found in the AUTHORS file in the root of the source tree. |
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// ----------------------------------------------------------------------------- |
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// |
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// Sharp RGB to YUV conversion. |
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#ifndef WEBP_SHARPYUV_SHARPYUV_H_ |
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#define WEBP_SHARPYUV_SHARPYUV_H_ |
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#ifdef __cplusplus |
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extern "C" { |
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#endif |
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#ifndef SHARPYUV_EXTERN |
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#ifdef WEBP_EXTERN |
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#define SHARPYUV_EXTERN WEBP_EXTERN |
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#else |
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// This explicitly marks library functions and allows for changing the |
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// signature for e.g., Windows DLL builds. |
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#if defined(_WIN32) && defined(WEBP_DLL) |
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#define SHARPYUV_EXTERN __declspec(dllexport) |
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#elif defined(__GNUC__) && __GNUC__ >= 4 |
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#define SHARPYUV_EXTERN extern __attribute__((visibility("default"))) |
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#else |
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#define SHARPYUV_EXTERN extern |
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#endif /* defined(_WIN32) && defined(WEBP_DLL) */ |
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#endif /* WEBP_EXTERN */ |
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#endif /* SHARPYUV_EXTERN */ |
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#ifndef SHARPYUV_INLINE |
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#ifdef WEBP_INLINE |
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#define SHARPYUV_INLINE WEBP_INLINE |
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#else |
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#ifndef _MSC_VER |
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#if defined(__cplusplus) || !defined(__STRICT_ANSI__) || \ |
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(defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) |
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#define SHARPYUV_INLINE inline |
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#else |
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#define SHARPYUV_INLINE |
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#endif |
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#else |
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#define SHARPYUV_INLINE __forceinline |
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#endif /* _MSC_VER */ |
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#endif /* WEBP_INLINE */ |
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#endif /* SHARPYUV_INLINE */ |
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// SharpYUV API version following the convention from semver.org |
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#define SHARPYUV_VERSION_MAJOR 0 |
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#define SHARPYUV_VERSION_MINOR 4 |
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#define SHARPYUV_VERSION_PATCH 0 |
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// Version as a uint32_t. The major number is the high 8 bits. |
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// The minor number is the middle 8 bits. The patch number is the low 16 bits. |
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#define SHARPYUV_MAKE_VERSION(MAJOR, MINOR, PATCH) \ |
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(((MAJOR) << 24) | ((MINOR) << 16) | (PATCH)) |
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#define SHARPYUV_VERSION \ |
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SHARPYUV_MAKE_VERSION(SHARPYUV_VERSION_MAJOR, SHARPYUV_VERSION_MINOR, \ |
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SHARPYUV_VERSION_PATCH) |
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// Returns the library's version number, packed in hexadecimal. See |
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// SHARPYUV_VERSION. |
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SHARPYUV_EXTERN int SharpYuvGetVersion(void); |
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// RGB to YUV conversion matrix, in 16 bit fixed point. |
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// y = rgb_to_y[0] * r + rgb_to_y[1] * g + rgb_to_y[2] * b + rgb_to_y[3] |
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// u = rgb_to_u[0] * r + rgb_to_u[1] * g + rgb_to_u[2] * b + rgb_to_u[3] |
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// v = rgb_to_v[0] * r + rgb_to_v[1] * g + rgb_to_v[2] * b + rgb_to_v[3] |
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// Then y, u and v values are divided by 1<<16 and rounded. |
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typedef struct { |
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int rgb_to_y[4]; |
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int rgb_to_u[4]; |
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int rgb_to_v[4]; |
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} SharpYuvConversionMatrix; |
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typedef struct SharpYuvOptions SharpYuvOptions; |
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// Enums for transfer functions, as defined in H.273, |
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// https://www.itu.int/rec/T-REC-H.273-202107-I/en |
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typedef enum SharpYuvTransferFunctionType { |
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// 0 is reserved |
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kSharpYuvTransferFunctionBt709 = 1, |
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// 2 is unspecified |
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// 3 is reserved |
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kSharpYuvTransferFunctionBt470M = 4, |
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kSharpYuvTransferFunctionBt470Bg = 5, |
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kSharpYuvTransferFunctionBt601 = 6, |
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kSharpYuvTransferFunctionSmpte240 = 7, |
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kSharpYuvTransferFunctionLinear = 8, |
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kSharpYuvTransferFunctionLog100 = 9, |
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kSharpYuvTransferFunctionLog100_Sqrt10 = 10, |
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kSharpYuvTransferFunctionIec61966 = 11, |
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kSharpYuvTransferFunctionBt1361 = 12, |
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kSharpYuvTransferFunctionSrgb = 13, |
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kSharpYuvTransferFunctionBt2020_10Bit = 14, |
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kSharpYuvTransferFunctionBt2020_12Bit = 15, |
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kSharpYuvTransferFunctionSmpte2084 = 16, // PQ |
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kSharpYuvTransferFunctionSmpte428 = 17, |
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kSharpYuvTransferFunctionHlg = 18, |
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kSharpYuvTransferFunctionNum |
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} SharpYuvTransferFunctionType; |
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// Converts RGB to YUV420 using a downsampling algorithm that minimizes |
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// artefacts caused by chroma subsampling. |
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// This is slower than standard downsampling (averaging of 4 UV values). |
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// Assumes that the image will be upsampled using a bilinear filter. If nearest |
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// neighbor is used instead, the upsampled image might look worse than with |
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// standard downsampling. |
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// r_ptr, g_ptr, b_ptr: pointers to the source r, g and b channels. Should point |
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// to uint8_t buffers if rgb_bit_depth is 8, or uint16_t buffers otherwise. |
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// rgb_step: distance in bytes between two horizontally adjacent pixels on the |
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// r, g and b channels. If rgb_bit_depth is > 8, it should be a |
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// multiple of 2. |
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// rgb_stride: distance in bytes between two vertically adjacent pixels on the |
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// r, g, and b channels. If rgb_bit_depth is > 8, it should be a |
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// multiple of 2. |
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// rgb_bit_depth: number of bits for each r/g/b value. One of: 8, 10, 12, 16. |
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// Note: 16 bit input is truncated to 14 bits before conversion to yuv. |
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// yuv_bit_depth: number of bits for each y/u/v value. One of: 8, 10, 12. |
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// y_ptr, u_ptr, v_ptr: pointers to the destination y, u and v channels. Should |
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// point to uint8_t buffers if yuv_bit_depth is 8, or uint16_t buffers |
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// otherwise. |
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// y_stride, u_stride, v_stride: distance in bytes between two vertically |
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// adjacent pixels on the y, u and v channels. If yuv_bit_depth > 8, they |
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// should be multiples of 2. |
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// width, height: width and height of the image in pixels |
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// This function calls SharpYuvConvertWithOptions with a default transfer |
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// function of kSharpYuvTransferFunctionSrgb. |
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SHARPYUV_EXTERN int SharpYuvConvert(const void* r_ptr, const void* g_ptr, |
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const void* b_ptr, int rgb_step, |
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int rgb_stride, int rgb_bit_depth, |
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void* y_ptr, int y_stride, void* u_ptr, |
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int u_stride, void* v_ptr, int v_stride, |
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int yuv_bit_depth, int width, int height, |
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const SharpYuvConversionMatrix* yuv_matrix); |
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struct SharpYuvOptions { |
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// This matrix cannot be NULL and can be initialized by |
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// SharpYuvComputeConversionMatrix. |
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const SharpYuvConversionMatrix* yuv_matrix; |
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SharpYuvTransferFunctionType transfer_type; |
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}; |
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// Internal, version-checked, entry point |
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SHARPYUV_EXTERN int SharpYuvOptionsInitInternal(const SharpYuvConversionMatrix*, |
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SharpYuvOptions*, int); |
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// Should always be called, to initialize a fresh SharpYuvOptions |
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// structure before modification. SharpYuvOptionsInit() must have succeeded |
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// before using the 'options' object. |
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static SHARPYUV_INLINE int SharpYuvOptionsInit( |
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const SharpYuvConversionMatrix* yuv_matrix, SharpYuvOptions* options) { |
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return SharpYuvOptionsInitInternal(yuv_matrix, options, SHARPYUV_VERSION); |
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} |
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SHARPYUV_EXTERN int SharpYuvConvertWithOptions( |
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const void* r_ptr, const void* g_ptr, const void* b_ptr, int rgb_step, |
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int rgb_stride, int rgb_bit_depth, void* y_ptr, int y_stride, void* u_ptr, |
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int u_stride, void* v_ptr, int v_stride, int yuv_bit_depth, int width, |
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int height, const SharpYuvOptions* options); |
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// TODO(b/194336375): Add YUV444 to YUV420 conversion. Maybe also add 422 |
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// support (it's rarely used in practice, especially for images). |
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#ifdef __cplusplus |
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} // extern "C" |
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#endif |
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#endif // WEBP_SHARPYUV_SHARPYUV_H_
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