yuv.h revision 88fe2b83c4b9232cd08729556fd0485d6a6a92cd 
1// Copyright 2010 Google Inc.
2//
3// This code is licensed under the same terms as WebM:
4//  Software License Agreement:  http://www.webmproject.org/license/software/
5//  Additional IP Rights Grant:  http://www.webmproject.org/license/additional/
6// -----------------------------------------------------------------------------
7//
8// inline YUV->RGB conversion function
9//
10// Author: Skal (pascal.massimino@gmail.com)
11
12#ifndef WEBP_DEC_YUV_H_
13#define WEBP_DEC_YUV_H_
14
15#include "webp/decode_vp8.h"
16
17/*
18 * Define ANDROID_WEBP_RGB to enable specific optimizations for Android
19 * RGBA_4444 & RGB_565 color support.
20 *
21 */
22
23#define ANDROID_WEBP_RGB
24
25#if defined(__cplusplus) || defined(c_plusplus)
26extern "C" {
27#endif
28
29enum { YUV_FIX = 16,                // fixed-point precision
30       YUV_RANGE_MIN = -227,        // min value of r/g/b output
31       YUV_RANGE_MAX = 256 + 226    // max value of r/g/b output
32};
33extern int16_t VP8kVToR[256], VP8kUToB[256];
34extern int32_t VP8kVToG[256], VP8kUToG[256];
35extern uint8_t VP8kClip[YUV_RANGE_MAX - YUV_RANGE_MIN];
36extern uint8_t VP8kClip4Bits[YUV_RANGE_MAX - YUV_RANGE_MIN];
37
38static inline void VP8YuvToRgb(uint8_t y, uint8_t u, uint8_t v,
39                               uint8_t* const rgb) {
40  const int r_off = VP8kVToR[v];
41  const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
42  const int b_off = VP8kUToB[u];
43  rgb[0] = VP8kClip[y + r_off - YUV_RANGE_MIN];
44  rgb[1] = VP8kClip[y + g_off - YUV_RANGE_MIN];
45  rgb[2] = VP8kClip[y + b_off - YUV_RANGE_MIN];
46}
47
48static inline void VP8YuvToRgb565(uint8_t y, uint8_t u, uint8_t v,
49                                  uint8_t* const rgb) {
50  const int r_off = VP8kVToR[v];
51  const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
52  const int b_off = VP8kUToB[u];
53#ifdef ANDROID_WEBP_RGB
54  rgb[1] = ((VP8kClip[y + r_off - YUV_RANGE_MIN] & 0xf8) |
55            (VP8kClip[y + g_off - YUV_RANGE_MIN] >> 5));
56  rgb[0] = (((VP8kClip[y + g_off - YUV_RANGE_MIN] << 3) & 0xe0) |
57            (VP8kClip[y + b_off - YUV_RANGE_MIN] >> 3));
58#else
59  rgb[0] = ((VP8kClip[y + r_off - YUV_RANGE_MIN] & 0xf8) |
60            (VP8kClip[y + g_off - YUV_RANGE_MIN] >> 5));
61  rgb[1] = (((VP8kClip[y + g_off - YUV_RANGE_MIN] << 3) & 0xe0) |
62            (VP8kClip[y + b_off - YUV_RANGE_MIN] >> 3));
63#endif
64}
65
66static inline void VP8YuvToArgbKeepA(uint8_t y, uint8_t u, uint8_t v,
67                                     uint8_t* const argb) {
68  // Don't update Aplha (argb[0])
69  VP8YuvToRgb(y, u, v, argb + 1);
70}
71
72static inline void VP8YuvToArgb(uint8_t y, uint8_t u, uint8_t v,
73                                uint8_t* const argb) {
74  argb[0] = 0xff;
75  VP8YuvToArgbKeepA(y, u, v, argb);
76}
77
78static inline void VP8YuvToRgba4444KeepA(uint8_t y, uint8_t u, uint8_t v,
79                                         uint8_t* const argb) {
80  const int r_off = VP8kVToR[v];
81  const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
82  const int b_off = VP8kUToB[u];
83#ifdef ANDROID_WEBP_RGB
84  argb[1] = ((VP8kClip4Bits[y + r_off - YUV_RANGE_MIN] << 4) |
85             VP8kClip4Bits[y + g_off - YUV_RANGE_MIN]);
86  argb[0] = (argb[0] & 0x0f) | (VP8kClip4Bits[y + b_off - YUV_RANGE_MIN] << 4);
87#else
88  argb[0] = ((VP8kClip4Bits[y + r_off - YUV_RANGE_MIN] << 4) |
89             VP8kClip4Bits[y + g_off - YUV_RANGE_MIN]);
90  argb[1] = (argb[1] & 0x0f) | (VP8kClip4Bits[y + b_off - YUV_RANGE_MIN] << 4);
91#endif
92}
93
94static inline void VP8YuvToRgba4444(uint8_t y, uint8_t u, uint8_t v,
95                                    uint8_t* const argb) {
96#ifdef ANDROID_WEBP_RGB
97  argb[0] = 0x0f;
98#else
99  argb[1] = 0x0f;
100#endif
101  VP8YuvToRgba4444KeepA(y, u, v, argb);
102}
103
104static inline void VP8YuvToBgr(uint8_t y, uint8_t u, uint8_t v,
105                               uint8_t* const bgr) {
106  const int r_off = VP8kVToR[v];
107  const int g_off = (VP8kVToG[v] + VP8kUToG[u]) >> YUV_FIX;
108  const int b_off = VP8kUToB[u];
109  bgr[0] = VP8kClip[y + b_off - YUV_RANGE_MIN];
110  bgr[1] = VP8kClip[y + g_off - YUV_RANGE_MIN];
111  bgr[2] = VP8kClip[y + r_off - YUV_RANGE_MIN];
112}
113
114static inline void VP8YuvToBgra(uint8_t y, uint8_t u, uint8_t v,
115                                uint8_t* const bgra) {
116  VP8YuvToBgr(y, u, v, bgra);
117  bgra[3] = 0xff;
118}
119
120static inline void VP8YuvToRgba(uint8_t y, uint8_t u, uint8_t v,
121                                uint8_t* const rgba) {
122  VP8YuvToRgb(y, u, v, rgba);
123  rgba[3] = 0xff;
124}
125
126// Must be called before everything, to initialize the tables.
127void VP8YUVInit(void);
128
129#if defined(__cplusplus) || defined(c_plusplus)
130}    // extern "C"
131#endif
132
133#endif  // WEBP_DEC_YUV_H_
134