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// Author: Skal (pascal.massimino@gmail.com)
13
14#include "sharpyuv/sharpyuv.h"
15
16#include <assert.h>
17#include <limits.h>
18#include <stddef.h>
19#include <stdlib.h>
20#include <string.h>
21
22#include "src/webp/types.h"
23#include "sharpyuv/sharpyuv_cpu.h"
24#include "sharpyuv/sharpyuv_dsp.h"
25#include "sharpyuv/sharpyuv_gamma.h"
26
27//------------------------------------------------------------------------------
28
29int SharpYuvGetVersion(void) {
30 return SHARPYUV_VERSION;
31}
32
33//------------------------------------------------------------------------------
34// Sharp RGB->YUV conversion
35
36static const int kNumIterations = 4;
37
38#define YUV_FIX 16 // fixed-point precision for RGB->YUV
39static const int kYuvHalf = 1 << (YUV_FIX - 1);
40
41// Max bit depth so that intermediate calculations fit in 16 bits.
42static const int kMaxBitDepth = 14;
43
44// Returns the precision shift to use based on the input rgb_bit_depth.
45static int GetPrecisionShift(int rgb_bit_depth) {
46 // Try to add 2 bits of precision if it fits in kMaxBitDepth. Otherwise remove
47 // bits if needed.
48 return ((rgb_bit_depth + 2) <= kMaxBitDepth) ? 2
49 : (kMaxBitDepth - rgb_bit_depth);
50}
51
52typedef int16_t fixed_t; // signed type with extra precision for UV
53typedef uint16_t fixed_y_t; // unsigned type with extra precision for W
54
55//------------------------------------------------------------------------------
56
57static uint8_t clip_8b(fixed_t v) {
58 return (!(v & ~0xff)) ? (uint8_t)v : (v < 0) ? 0u : 255u;
59}
60
61static uint16_t clip(fixed_t v, int max) {
62 return (v < 0) ? 0 : (v > max) ? max : (uint16_t)v;
63}
64
65static fixed_y_t clip_bit_depth(int y, int bit_depth) {
66 const int max = (1 << bit_depth) - 1;
67 return (!(y & ~max)) ? (fixed_y_t)y : (y < 0) ? 0 : max;
68}
69
70//------------------------------------------------------------------------------
71
72static int RGBToGray(int64_t r, int64_t g, int64_t b) {
73 const int64_t luma = 13933 * r + 46871 * g + 4732 * b + kYuvHalf;
74 return (int)(luma >> YUV_FIX);
75}
76
77static uint32_t ScaleDown(uint16_t a, uint16_t b, uint16_t c, uint16_t d,
78 int rgb_bit_depth,
79 SharpYuvTransferFunctionType transfer_type) {
80 const int bit_depth = rgb_bit_depth + GetPrecisionShift(rgb_bit_depth);
81 const uint32_t A = SharpYuvGammaToLinear(v: a, bit_depth, transfer_type);
82 const uint32_t B = SharpYuvGammaToLinear(v: b, bit_depth, transfer_type);
83 const uint32_t C = SharpYuvGammaToLinear(v: c, bit_depth, transfer_type);
84 const uint32_t D = SharpYuvGammaToLinear(v: d, bit_depth, transfer_type);
85 return SharpYuvLinearToGamma(value: (A + B + C + D + 2) >> 2, bit_depth,
86 transfer_type);
87}
88
89static WEBP_INLINE void UpdateW(const fixed_y_t* src, fixed_y_t* dst, int w,
90 int rgb_bit_depth,
91 SharpYuvTransferFunctionType transfer_type) {
92 const int bit_depth = rgb_bit_depth + GetPrecisionShift(rgb_bit_depth);
93 int i = 0;
94 do {
95 const uint32_t R =
96 SharpYuvGammaToLinear(v: src[0 * w + i], bit_depth, transfer_type);
97 const uint32_t G =
98 SharpYuvGammaToLinear(v: src[1 * w + i], bit_depth, transfer_type);
99 const uint32_t B =
100 SharpYuvGammaToLinear(v: src[2 * w + i], bit_depth, transfer_type);
101 const uint32_t Y = RGBToGray(r: R, g: G, b: B);
102 dst[i] = (fixed_y_t)SharpYuvLinearToGamma(value: Y, bit_depth, transfer_type);
103 } while (++i < w);
104}
105
106static void UpdateChroma(const fixed_y_t* src1, const fixed_y_t* src2,
107 fixed_t* dst, int uv_w, int rgb_bit_depth,
108 SharpYuvTransferFunctionType transfer_type) {
109 int i = 0;
110 do {
111 const int r =
112 ScaleDown(a: src1[0 * uv_w + 0], b: src1[0 * uv_w + 1], c: src2[0 * uv_w + 0],
113 d: src2[0 * uv_w + 1], rgb_bit_depth, transfer_type);
114 const int g =
115 ScaleDown(a: src1[2 * uv_w + 0], b: src1[2 * uv_w + 1], c: src2[2 * uv_w + 0],
116 d: src2[2 * uv_w + 1], rgb_bit_depth, transfer_type);
117 const int b =
118 ScaleDown(a: src1[4 * uv_w + 0], b: src1[4 * uv_w + 1], c: src2[4 * uv_w + 0],
119 d: src2[4 * uv_w + 1], rgb_bit_depth, transfer_type);
120 const int W = RGBToGray(r, g, b);
121 dst[0 * uv_w] = (fixed_t)(r - W);
122 dst[1 * uv_w] = (fixed_t)(g - W);
123 dst[2 * uv_w] = (fixed_t)(b - W);
124 dst += 1;
125 src1 += 2;
126 src2 += 2;
127 } while (++i < uv_w);
128}
129
130static void StoreGray(const fixed_y_t* rgb, fixed_y_t* y, int w) {
131 int i = 0;
132 assert(w > 0);
133 do {
134 y[i] = RGBToGray(r: rgb[0 * w + i], g: rgb[1 * w + i], b: rgb[2 * w + i]);
135 } while (++i < w);
136}
137
138//------------------------------------------------------------------------------
139
140static WEBP_INLINE fixed_y_t Filter2(int A, int B, int W0, int bit_depth) {
141 const int v0 = (A * 3 + B + 2) >> 2;
142 return clip_bit_depth(y: v0 + W0, bit_depth);
143}
144
145//------------------------------------------------------------------------------
146
147static WEBP_INLINE int Shift(int v, int shift) {
148 return (shift >= 0) ? (v << shift) : (v >> -shift);
149}
150
151static void ImportOneRow(const uint8_t* const r_ptr,
152 const uint8_t* const g_ptr,
153 const uint8_t* const b_ptr,
154 int rgb_step,
155 int rgb_bit_depth,
156 int pic_width,
157 fixed_y_t* const dst) {
158 // Convert the rgb_step from a number of bytes to a number of uint8_t or
159 // uint16_t values depending the bit depth.
160 const int step = (rgb_bit_depth > 8) ? rgb_step / 2 : rgb_step;
161 int i = 0;
162 const int w = (pic_width + 1) & ~1;
163 do {
164 const int off = i * step;
165 const int shift = GetPrecisionShift(rgb_bit_depth);
166 if (rgb_bit_depth == 8) {
167 dst[i + 0 * w] = Shift(v: r_ptr[off], shift);
168 dst[i + 1 * w] = Shift(v: g_ptr[off], shift);
169 dst[i + 2 * w] = Shift(v: b_ptr[off], shift);
170 } else {
171 dst[i + 0 * w] = Shift(v: ((uint16_t*)r_ptr)[off], shift);
172 dst[i + 1 * w] = Shift(v: ((uint16_t*)g_ptr)[off], shift);
173 dst[i + 2 * w] = Shift(v: ((uint16_t*)b_ptr)[off], shift);
174 }
175 } while (++i < pic_width);
176 if (pic_width & 1) { // replicate rightmost pixel
177 dst[pic_width + 0 * w] = dst[pic_width + 0 * w - 1];
178 dst[pic_width + 1 * w] = dst[pic_width + 1 * w - 1];
179 dst[pic_width + 2 * w] = dst[pic_width + 2 * w - 1];
180 }
181}
182
183static void InterpolateTwoRows(const fixed_y_t* const best_y,
184 const fixed_t* prev_uv,
185 const fixed_t* cur_uv,
186 const fixed_t* next_uv,
187 int w,
188 fixed_y_t* out1,
189 fixed_y_t* out2,
190 int rgb_bit_depth) {
191 const int uv_w = w >> 1;
192 const int len = (w - 1) >> 1; // length to filter
193 int k = 3;
194 const int bit_depth = rgb_bit_depth + GetPrecisionShift(rgb_bit_depth);
195 while (k-- > 0) { // process each R/G/B segments in turn
196 // special boundary case for i==0
197 out1[0] = Filter2(A: cur_uv[0], B: prev_uv[0], W0: best_y[0], bit_depth);
198 out2[0] = Filter2(A: cur_uv[0], B: next_uv[0], W0: best_y[w], bit_depth);
199
200 SharpYuvFilterRow(cur_uv, prev_uv, len, best_y + 0 + 1, out1 + 1,
201 bit_depth);
202 SharpYuvFilterRow(cur_uv, next_uv, len, best_y + w + 1, out2 + 1,
203 bit_depth);
204
205 // special boundary case for i == w - 1 when w is even
206 if (!(w & 1)) {
207 out1[w - 1] = Filter2(A: cur_uv[uv_w - 1], B: prev_uv[uv_w - 1],
208 W0: best_y[w - 1 + 0], bit_depth);
209 out2[w - 1] = Filter2(A: cur_uv[uv_w - 1], B: next_uv[uv_w - 1],
210 W0: best_y[w - 1 + w], bit_depth);
211 }
212 out1 += w;
213 out2 += w;
214 prev_uv += uv_w;
215 cur_uv += uv_w;
216 next_uv += uv_w;
217 }
218}
219
220static WEBP_INLINE int RGBToYUVComponent(int r, int g, int b,
221 const int coeffs[4], int sfix) {
222 const int srounder = 1 << (YUV_FIX + sfix - 1);
223 const int luma = coeffs[0] * r + coeffs[1] * g + coeffs[2] * b +
224 coeffs[3] + srounder;
225 return (luma >> (YUV_FIX + sfix));
226}
227
228static int ConvertWRGBToYUV(const fixed_y_t* best_y, const fixed_t* best_uv,
229 uint8_t* y_ptr, int y_stride, uint8_t* u_ptr,
230 int u_stride, uint8_t* v_ptr, int v_stride,
231 int rgb_bit_depth,
232 int yuv_bit_depth, int width, int height,
233 const SharpYuvConversionMatrix* yuv_matrix) {
234 int i, j;
235 const fixed_t* const best_uv_base = best_uv;
236 const int w = (width + 1) & ~1;
237 const int h = (height + 1) & ~1;
238 const int uv_w = w >> 1;
239 const int uv_h = h >> 1;
240 const int sfix = GetPrecisionShift(rgb_bit_depth);
241 const int yuv_max = (1 << yuv_bit_depth) - 1;
242
243 best_uv = best_uv_base;
244 j = 0;
245 do {
246 i = 0;
247 do {
248 const int off = (i >> 1);
249 const int W = best_y[i];
250 const int r = best_uv[off + 0 * uv_w] + W;
251 const int g = best_uv[off + 1 * uv_w] + W;
252 const int b = best_uv[off + 2 * uv_w] + W;
253 const int y = RGBToYUVComponent(r, g, b, coeffs: yuv_matrix->rgb_to_y, sfix);
254 if (yuv_bit_depth <= 8) {
255 y_ptr[i] = clip_8b(v: y);
256 } else {
257 ((uint16_t*)y_ptr)[i] = clip(v: y, max: yuv_max);
258 }
259 } while (++i < width);
260 best_y += w;
261 best_uv += (j & 1) * 3 * uv_w;
262 y_ptr += y_stride;
263 } while (++j < height);
264
265 best_uv = best_uv_base;
266 j = 0;
267 do {
268 i = 0;
269 do {
270 // Note r, g and b values here are off by W, but a constant offset on all
271 // 3 components doesn't change the value of u and v with a YCbCr matrix.
272 const int r = best_uv[i + 0 * uv_w];
273 const int g = best_uv[i + 1 * uv_w];
274 const int b = best_uv[i + 2 * uv_w];
275 const int u = RGBToYUVComponent(r, g, b, coeffs: yuv_matrix->rgb_to_u, sfix);
276 const int v = RGBToYUVComponent(r, g, b, coeffs: yuv_matrix->rgb_to_v, sfix);
277 if (yuv_bit_depth <= 8) {
278 u_ptr[i] = clip_8b(v: u);
279 v_ptr[i] = clip_8b(v);
280 } else {
281 ((uint16_t*)u_ptr)[i] = clip(v: u, max: yuv_max);
282 ((uint16_t*)v_ptr)[i] = clip(v, max: yuv_max);
283 }
284 } while (++i < uv_w);
285 best_uv += 3 * uv_w;
286 u_ptr += u_stride;
287 v_ptr += v_stride;
288 } while (++j < uv_h);
289 return 1;
290}
291
292//------------------------------------------------------------------------------
293// Main function
294
295static void* SafeMalloc(uint64_t nmemb, size_t size) {
296 const uint64_t total_size = nmemb * (uint64_t)size;
297 if (total_size != (size_t)total_size) return NULL;
298 return malloc(size: (size_t)total_size);
299}
300
301#define SAFE_ALLOC(W, H, T) ((T*)SafeMalloc((uint64_t)(W) * (H), sizeof(T)))
302
303static int DoSharpArgbToYuv(const uint8_t* r_ptr, const uint8_t* g_ptr,
304 const uint8_t* b_ptr, int rgb_step, int rgb_stride,
305 int rgb_bit_depth, uint8_t* y_ptr, int y_stride,
306 uint8_t* u_ptr, int u_stride, uint8_t* v_ptr,
307 int v_stride, int yuv_bit_depth, int width,
308 int height,
309 const SharpYuvConversionMatrix* yuv_matrix,
310 SharpYuvTransferFunctionType transfer_type) {
311 // we expand the right/bottom border if needed
312 const int w = (width + 1) & ~1;
313 const int h = (height + 1) & ~1;
314 const int uv_w = w >> 1;
315 const int uv_h = h >> 1;
316 const int y_bit_depth = rgb_bit_depth + GetPrecisionShift(rgb_bit_depth);
317 uint64_t prev_diff_y_sum = ~0;
318 int j, iter;
319
320 // TODO(skal): allocate one big memory chunk. But for now, it's easier
321 // for valgrind debugging to have several chunks.
322 fixed_y_t* const tmp_buffer = SAFE_ALLOC(w * 3, 2, fixed_y_t); // scratch
323 fixed_y_t* const best_y_base = SAFE_ALLOC(w, h, fixed_y_t);
324 fixed_y_t* const target_y_base = SAFE_ALLOC(w, h, fixed_y_t);
325 fixed_y_t* const best_rgb_y = SAFE_ALLOC(w, 2, fixed_y_t);
326 fixed_t* const best_uv_base = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t);
327 fixed_t* const target_uv_base = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t);
328 fixed_t* const best_rgb_uv = SAFE_ALLOC(uv_w * 3, 1, fixed_t);
329 fixed_y_t* best_y = best_y_base;
330 fixed_y_t* target_y = target_y_base;
331 fixed_t* best_uv = best_uv_base;
332 fixed_t* target_uv = target_uv_base;
333 const uint64_t diff_y_threshold = (uint64_t)(3.0 * w * h);
334 int ok;
335 assert(w > 0);
336 assert(h > 0);
337
338 if (best_y_base == NULL || best_uv_base == NULL ||
339 target_y_base == NULL || target_uv_base == NULL ||
340 best_rgb_y == NULL || best_rgb_uv == NULL ||
341 tmp_buffer == NULL) {
342 ok = 0;
343 goto End;
344 }
345
346 // Import RGB samples to W/RGB representation.
347 for (j = 0; j < height; j += 2) {
348 const int is_last_row = (j == height - 1);
349 fixed_y_t* const src1 = tmp_buffer + 0 * w;
350 fixed_y_t* const src2 = tmp_buffer + 3 * w;
351
352 // prepare two rows of input
353 ImportOneRow(r_ptr, g_ptr, b_ptr, rgb_step, rgb_bit_depth, pic_width: width,
354 dst: src1);
355 if (!is_last_row) {
356 ImportOneRow(r_ptr: r_ptr + rgb_stride, g_ptr: g_ptr + rgb_stride, b_ptr: b_ptr + rgb_stride,
357 rgb_step, rgb_bit_depth, pic_width: width, dst: src2);
358 } else {
359 memcpy(dest: src2, src: src1, n: 3 * w * sizeof(*src2));
360 }
361 StoreGray(rgb: src1, y: best_y + 0, w);
362 StoreGray(rgb: src2, y: best_y + w, w);
363
364 UpdateW(src: src1, dst: target_y, w, rgb_bit_depth, transfer_type);
365 UpdateW(src: src2, dst: target_y + w, w, rgb_bit_depth, transfer_type);
366 UpdateChroma(src1, src2, dst: target_uv, uv_w, rgb_bit_depth, transfer_type);
367 memcpy(dest: best_uv, src: target_uv, n: 3 * uv_w * sizeof(*best_uv));
368 best_y += 2 * w;
369 best_uv += 3 * uv_w;
370 target_y += 2 * w;
371 target_uv += 3 * uv_w;
372 r_ptr += 2 * rgb_stride;
373 g_ptr += 2 * rgb_stride;
374 b_ptr += 2 * rgb_stride;
375 }
376
377 // Iterate and resolve clipping conflicts.
378 for (iter = 0; iter < kNumIterations; ++iter) {
379 const fixed_t* cur_uv = best_uv_base;
380 const fixed_t* prev_uv = best_uv_base;
381 uint64_t diff_y_sum = 0;
382
383 best_y = best_y_base;
384 best_uv = best_uv_base;
385 target_y = target_y_base;
386 target_uv = target_uv_base;
387 j = 0;
388 do {
389 fixed_y_t* const src1 = tmp_buffer + 0 * w;
390 fixed_y_t* const src2 = tmp_buffer + 3 * w;
391 {
392 const fixed_t* const next_uv = cur_uv + ((j < h - 2) ? 3 * uv_w : 0);
393 InterpolateTwoRows(best_y, prev_uv, cur_uv, next_uv, w,
394 out1: src1, out2: src2, rgb_bit_depth);
395 prev_uv = cur_uv;
396 cur_uv = next_uv;
397 }
398
399 UpdateW(src: src1, dst: best_rgb_y + 0 * w, w, rgb_bit_depth, transfer_type);
400 UpdateW(src: src2, dst: best_rgb_y + 1 * w, w, rgb_bit_depth, transfer_type);
401 UpdateChroma(src1, src2, dst: best_rgb_uv, uv_w, rgb_bit_depth, transfer_type);
402
403 // update two rows of Y and one row of RGB
404 diff_y_sum +=
405 SharpYuvUpdateY(target_y, best_rgb_y, best_y, 2 * w, y_bit_depth);
406 SharpYuvUpdateRGB(target_uv, best_rgb_uv, best_uv, 3 * uv_w);
407
408 best_y += 2 * w;
409 best_uv += 3 * uv_w;
410 target_y += 2 * w;
411 target_uv += 3 * uv_w;
412 j += 2;
413 } while (j < h);
414 // test exit condition
415 if (iter > 0) {
416 if (diff_y_sum < diff_y_threshold) break;
417 if (diff_y_sum > prev_diff_y_sum) break;
418 }
419 prev_diff_y_sum = diff_y_sum;
420 }
421
422 // final reconstruction
423 ok = ConvertWRGBToYUV(best_y: best_y_base, best_uv: best_uv_base, y_ptr, y_stride, u_ptr,
424 u_stride, v_ptr, v_stride, rgb_bit_depth, yuv_bit_depth,
425 width, height, yuv_matrix);
426
427 End:
428 free(ptr: best_y_base);
429 free(ptr: best_uv_base);
430 free(ptr: target_y_base);
431 free(ptr: target_uv_base);
432 free(ptr: best_rgb_y);
433 free(ptr: best_rgb_uv);
434 free(ptr: tmp_buffer);
435 return ok;
436}
437
438#undef SAFE_ALLOC
439
440#if defined(WEBP_USE_THREAD) && !defined(_WIN32)
441#include <pthread.h> // NOLINT
442
443#define LOCK_ACCESS \
444 static pthread_mutex_t sharpyuv_lock = PTHREAD_MUTEX_INITIALIZER; \
445 if (pthread_mutex_lock(&sharpyuv_lock)) return
446#define UNLOCK_ACCESS_AND_RETURN \
447 do { \
448 (void)pthread_mutex_unlock(&sharpyuv_lock); \
449 return; \
450 } while (0)
451#else // !(defined(WEBP_USE_THREAD) && !defined(_WIN32))
452#define LOCK_ACCESS do {} while (0)
453#define UNLOCK_ACCESS_AND_RETURN return
454#endif // defined(WEBP_USE_THREAD) && !defined(_WIN32)
455
456// Hidden exported init function.
457// By default SharpYuvConvert calls it with SharpYuvGetCPUInfo. If needed,
458// users can declare it as extern and call it with an alternate VP8CPUInfo
459// function.
460extern VP8CPUInfo SharpYuvGetCPUInfo;
461SHARPYUV_EXTERN void SharpYuvInit(VP8CPUInfo cpu_info_func);
462void SharpYuvInit(VP8CPUInfo cpu_info_func) {
463 static volatile VP8CPUInfo sharpyuv_last_cpuinfo_used =
464 (VP8CPUInfo)&sharpyuv_last_cpuinfo_used;
465 LOCK_ACCESS;
466 // Only update SharpYuvGetCPUInfo when called from external code to avoid a
467 // race on reading the value in SharpYuvConvert().
468 if (cpu_info_func != (VP8CPUInfo)&SharpYuvGetCPUInfo) {
469 SharpYuvGetCPUInfo = cpu_info_func;
470 }
471 if (sharpyuv_last_cpuinfo_used == SharpYuvGetCPUInfo) {
472 UNLOCK_ACCESS_AND_RETURN;
473 }
474
475 SharpYuvInitDsp();
476 SharpYuvInitGammaTables();
477
478 sharpyuv_last_cpuinfo_used = SharpYuvGetCPUInfo;
479 UNLOCK_ACCESS_AND_RETURN;
480}
481
482int SharpYuvConvert(const void* r_ptr, const void* g_ptr, const void* b_ptr,
483 int rgb_step, int rgb_stride, int rgb_bit_depth,
484 void* y_ptr, int y_stride, void* u_ptr, int u_stride,
485 void* v_ptr, int v_stride, int yuv_bit_depth, int width,
486 int height, const SharpYuvConversionMatrix* yuv_matrix) {
487 SharpYuvOptions options;
488 options.yuv_matrix = yuv_matrix;
489 options.transfer_type = kSharpYuvTransferFunctionSrgb;
490 return SharpYuvConvertWithOptions(
491 r_ptr, g_ptr, b_ptr, rgb_step, rgb_stride, rgb_bit_depth, y_ptr, y_stride,
492 u_ptr, u_stride, v_ptr, v_stride, yuv_bit_depth, width, height, options: &options);
493}
494
495int SharpYuvOptionsInitInternal(const SharpYuvConversionMatrix* yuv_matrix,
496 SharpYuvOptions* options, int version) {
497 const int major = (version >> 24);
498 const int minor = (version >> 16) & 0xff;
499 if (options == NULL || yuv_matrix == NULL ||
500 (major == SHARPYUV_VERSION_MAJOR && major == 0 &&
501 minor != SHARPYUV_VERSION_MINOR) ||
502 (major != SHARPYUV_VERSION_MAJOR)) {
503 return 0;
504 }
505 options->yuv_matrix = yuv_matrix;
506 options->transfer_type = kSharpYuvTransferFunctionSrgb;
507 return 1;
508}
509
510int SharpYuvConvertWithOptions(const void* r_ptr, const void* g_ptr,
511 const void* b_ptr, int rgb_step, int rgb_stride,
512 int rgb_bit_depth, void* y_ptr, int y_stride,
513 void* u_ptr, int u_stride, void* v_ptr,
514 int v_stride, int yuv_bit_depth, int width,
515 int height, const SharpYuvOptions* options) {
516 const SharpYuvConversionMatrix* yuv_matrix = options->yuv_matrix;
517 SharpYuvTransferFunctionType transfer_type = options->transfer_type;
518 SharpYuvConversionMatrix scaled_matrix;
519 const int rgb_max = (1 << rgb_bit_depth) - 1;
520 const int rgb_round = 1 << (rgb_bit_depth - 1);
521 const int yuv_max = (1 << yuv_bit_depth) - 1;
522 const int sfix = GetPrecisionShift(rgb_bit_depth);
523
524 if (width < 1 || height < 1 || width == INT_MAX || height == INT_MAX ||
525 r_ptr == NULL || g_ptr == NULL || b_ptr == NULL || y_ptr == NULL ||
526 u_ptr == NULL || v_ptr == NULL) {
527 return 0;
528 }
529 if (rgb_bit_depth != 8 && rgb_bit_depth != 10 && rgb_bit_depth != 12 &&
530 rgb_bit_depth != 16) {
531 return 0;
532 }
533 if (yuv_bit_depth != 8 && yuv_bit_depth != 10 && yuv_bit_depth != 12) {
534 return 0;
535 }
536 if (rgb_bit_depth > 8 && (rgb_step % 2 != 0 || rgb_stride % 2 != 0)) {
537 // Step/stride should be even for uint16_t buffers.
538 return 0;
539 }
540 if (yuv_bit_depth > 8 &&
541 (y_stride % 2 != 0 || u_stride % 2 != 0 || v_stride % 2 != 0)) {
542 // Stride should be even for uint16_t buffers.
543 return 0;
544 }
545 // The address of the function pointer is used to avoid a read race.
546 SharpYuvInit(cpu_info_func: (VP8CPUInfo)&SharpYuvGetCPUInfo);
547
548 // Add scaling factor to go from rgb_bit_depth to yuv_bit_depth, to the
549 // rgb->yuv conversion matrix.
550 if (rgb_bit_depth == yuv_bit_depth) {
551 memcpy(dest: &scaled_matrix, src: yuv_matrix, n: sizeof(scaled_matrix));
552 } else {
553 int i;
554 for (i = 0; i < 3; ++i) {
555 scaled_matrix.rgb_to_y[i] =
556 (yuv_matrix->rgb_to_y[i] * yuv_max + rgb_round) / rgb_max;
557 scaled_matrix.rgb_to_u[i] =
558 (yuv_matrix->rgb_to_u[i] * yuv_max + rgb_round) / rgb_max;
559 scaled_matrix.rgb_to_v[i] =
560 (yuv_matrix->rgb_to_v[i] * yuv_max + rgb_round) / rgb_max;
561 }
562 }
563 // Also incorporate precision change scaling.
564 scaled_matrix.rgb_to_y[3] = Shift(v: yuv_matrix->rgb_to_y[3], shift: sfix);
565 scaled_matrix.rgb_to_u[3] = Shift(v: yuv_matrix->rgb_to_u[3], shift: sfix);
566 scaled_matrix.rgb_to_v[3] = Shift(v: yuv_matrix->rgb_to_v[3], shift: sfix);
567
568 return DoSharpArgbToYuv(
569 r_ptr: (const uint8_t*)r_ptr, g_ptr: (const uint8_t*)g_ptr, b_ptr: (const uint8_t*)b_ptr,
570 rgb_step, rgb_stride, rgb_bit_depth, y_ptr: (uint8_t*)y_ptr, y_stride,
571 u_ptr: (uint8_t*)u_ptr, u_stride, v_ptr: (uint8_t*)v_ptr, v_stride, yuv_bit_depth,
572 width, height, yuv_matrix: &scaled_matrix, transfer_type);
573}
574
575//------------------------------------------------------------------------------
576

source code of qtimageformats/src/3rdparty/libwebp/sharpyuv/sharpyuv.c