129 lines
4.6 KiB
C
129 lines
4.6 KiB
C
// Copyright 2010 Google Inc. All Rights Reserved.
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//
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// This code is licensed under the same terms as WebM:
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// Software License Agreement: http://www.webmproject.org/license/software/
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// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
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// -----------------------------------------------------------------------------
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//
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// inline YUV<->RGB conversion function
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#ifndef WEBP_DSP_YUV_H_
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#define WEBP_DSP_YUV_H_
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#include "../dec/decode_vp8.h"
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//------------------------------------------------------------------------------
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// YUV -> RGB conversion
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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enum { YUV_FIX = 16, // fixed-point precision
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YUV_RANGE_MIN = -227, // min value of r/g/b output
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YUV_RANGE_MAX = 256 + 226 // max value of r/g/b output
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};
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extern int16_t VP8kVToR[256], VP8kUToB[256];
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extern int32_t VP8kVToG[256], VP8kUToG[256];
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extern uint8_t VP8kClip[YUV_RANGE_MAX - YUV_RANGE_MIN];
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extern uint8_t VP8kClip4Bits[YUV_RANGE_MAX - YUV_RANGE_MIN];
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static WEBP_INLINE void VP8YuvToRgb(uint8_t y, uint8_t u, uint8_t v,
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uint8_t* const rgb) {
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const int r_off = VP8kVToR[v];
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const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
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const int b_off = VP8kUToB[u];
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rgb[0] = VP8kClip[y + r_off - YUV_RANGE_MIN];
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rgb[1] = VP8kClip[y + g_off - YUV_RANGE_MIN];
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rgb[2] = VP8kClip[y + b_off - YUV_RANGE_MIN];
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}
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static WEBP_INLINE void VP8YuvToRgb565(uint8_t y, uint8_t u, uint8_t v,
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uint8_t* const rgb) {
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const int r_off = VP8kVToR[v];
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const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
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const int b_off = VP8kUToB[u];
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rgb[0] = ((VP8kClip[y + r_off - YUV_RANGE_MIN] & 0xf8) |
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(VP8kClip[y + g_off - YUV_RANGE_MIN] >> 5));
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rgb[1] = (((VP8kClip[y + g_off - YUV_RANGE_MIN] << 3) & 0xe0) |
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(VP8kClip[y + b_off - YUV_RANGE_MIN] >> 3));
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}
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static WEBP_INLINE void VP8YuvToArgb(uint8_t y, uint8_t u, uint8_t v,
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uint8_t* const argb) {
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argb[0] = 0xff;
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VP8YuvToRgb(y, u, v, argb + 1);
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}
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static WEBP_INLINE void VP8YuvToRgba4444(uint8_t y, uint8_t u, uint8_t v,
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uint8_t* const argb) {
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const int r_off = VP8kVToR[v];
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const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
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const int b_off = VP8kUToB[u];
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// Don't update alpha (last 4 bits of argb[1])
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argb[0] = ((VP8kClip4Bits[y + r_off - YUV_RANGE_MIN] << 4) |
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VP8kClip4Bits[y + g_off - YUV_RANGE_MIN]);
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argb[1] = 0x0f | (VP8kClip4Bits[y + b_off - YUV_RANGE_MIN] << 4);
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}
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static WEBP_INLINE void VP8YuvToBgr(uint8_t y, uint8_t u, uint8_t v,
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uint8_t* const bgr) {
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const int r_off = VP8kVToR[v];
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const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
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const int b_off = VP8kUToB[u];
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bgr[0] = VP8kClip[y + b_off - YUV_RANGE_MIN];
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bgr[1] = VP8kClip[y + g_off - YUV_RANGE_MIN];
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bgr[2] = VP8kClip[y + r_off - YUV_RANGE_MIN];
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}
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static WEBP_INLINE void VP8YuvToBgra(uint8_t y, uint8_t u, uint8_t v,
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uint8_t* const bgra) {
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VP8YuvToBgr(y, u, v, bgra);
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bgra[3] = 0xff;
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}
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static WEBP_INLINE void VP8YuvToRgba(uint8_t y, uint8_t u, uint8_t v,
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uint8_t* const rgba) {
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VP8YuvToRgb(y, u, v, rgba);
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rgba[3] = 0xff;
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}
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// Must be called before everything, to initialize the tables.
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void VP8YUVInit(void);
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//------------------------------------------------------------------------------
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// RGB -> YUV conversion
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// The exact naming is Y'CbCr, following the ITU-R BT.601 standard.
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// More information at: http://en.wikipedia.org/wiki/YCbCr
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// Y = 0.2569 * R + 0.5044 * G + 0.0979 * B + 16
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// U = -0.1483 * R - 0.2911 * G + 0.4394 * B + 128
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// V = 0.4394 * R - 0.3679 * G - 0.0715 * B + 128
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// We use 16bit fixed point operations.
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static WEBP_INLINE int VP8ClipUV(int v) {
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v = (v + (257 << (YUV_FIX + 2 - 1))) >> (YUV_FIX + 2);
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return ((v & ~0xff) == 0) ? v : (v < 0) ? 0 : 255;
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}
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static WEBP_INLINE int VP8RGBToY(int r, int g, int b) {
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const int kRound = (1 << (YUV_FIX - 1)) + (16 << YUV_FIX);
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const int luma = 16839 * r + 33059 * g + 6420 * b;
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return (luma + kRound) >> YUV_FIX; // no need to clip
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}
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static WEBP_INLINE int VP8RGBToU(int r, int g, int b) {
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return VP8ClipUV(-9719 * r - 19081 * g + 28800 * b);
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}
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static WEBP_INLINE int VP8RGBToV(int r, int g, int b) {
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return VP8ClipUV(+28800 * r - 24116 * g - 4684 * b);
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}
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#if defined(__cplusplus) || defined(c_plusplus)
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} // extern "C"
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#endif
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#endif /* WEBP_DSP_YUV_H_ */
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