1 // Copyright 2011 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 // Speed-critical functions. 11 // 12 // Author: Skal ([email protected]) 13 14 #ifndef WEBP_DSP_DSP_H_ 15 #define WEBP_DSP_DSP_H_ 16 17 #ifdef HAVE_CONFIG_H 18 #include "src/webp/config.h" 19 #endif 20 21 #include "src/dsp/cpu.h" 22 #include "src/webp/types.h" 23 24 #ifdef __cplusplus 25 extern "C" { 26 #endif 27 28 #define BPS 32 // this is the common stride for enc/dec 29 30 //------------------------------------------------------------------------------ 31 // WEBP_RESTRICT 32 33 // Declares a pointer with the restrict type qualifier if available. 34 // This allows code to hint to the compiler that only this pointer references a 35 // particular object or memory region within the scope of the block in which it 36 // is declared. This may allow for improved optimizations due to the lack of 37 // pointer aliasing. See also: 38 // https://en.cppreference.com/w/c/language/restrict 39 #if defined(__GNUC__) 40 #define WEBP_RESTRICT __restrict__ 41 #elif defined(_MSC_VER) 42 #define WEBP_RESTRICT __restrict 43 #else 44 #define WEBP_RESTRICT 45 #endif 46 47 48 //------------------------------------------------------------------------------ 49 // Init stub generator 50 51 // Defines an init function stub to ensure each module exposes a symbol, 52 // avoiding a compiler warning. 53 #define WEBP_DSP_INIT_STUB(func) \ 54 extern void func(void); \ 55 void func(void) {} 56 57 //------------------------------------------------------------------------------ 58 // Encoding 59 60 // Transforms 61 // VP8Idct: Does one of two inverse transforms. If do_two is set, the transforms 62 // will be done for (ref, in, dst) and (ref + 4, in + 16, dst + 4). 63 typedef void (*VP8Idct)(const uint8_t* ref, const int16_t* in, uint8_t* dst, 64 int do_two); 65 typedef void (*VP8Fdct)(const uint8_t* src, const uint8_t* ref, int16_t* out); 66 typedef void (*VP8WHT)(const int16_t* in, int16_t* out); 67 extern VP8Idct VP8ITransform; 68 extern VP8Fdct VP8FTransform; 69 extern VP8Fdct VP8FTransform2; // performs two transforms at a time 70 extern VP8WHT VP8FTransformWHT; 71 // Predictions 72 // *dst is the destination block. *top and *left can be NULL. 73 typedef void (*VP8IntraPreds)(uint8_t* dst, const uint8_t* left, 74 const uint8_t* top); 75 typedef void (*VP8Intra4Preds)(uint8_t* dst, const uint8_t* top); 76 extern VP8Intra4Preds VP8EncPredLuma4; 77 extern VP8IntraPreds VP8EncPredLuma16; 78 extern VP8IntraPreds VP8EncPredChroma8; 79 80 typedef int (*VP8Metric)(const uint8_t* pix, const uint8_t* ref); 81 extern VP8Metric VP8SSE16x16, VP8SSE16x8, VP8SSE8x8, VP8SSE4x4; 82 typedef int (*VP8WMetric)(const uint8_t* pix, const uint8_t* ref, 83 const uint16_t* const weights); 84 // The weights for VP8TDisto4x4 and VP8TDisto16x16 contain a row-major 85 // 4 by 4 symmetric matrix. 86 extern VP8WMetric VP8TDisto4x4, VP8TDisto16x16; 87 88 // Compute the average (DC) of four 4x4 blocks. 89 // Each sub-4x4 block #i sum is stored in dc[i]. 90 typedef void (*VP8MeanMetric)(const uint8_t* ref, uint32_t dc[4]); 91 extern VP8MeanMetric VP8Mean16x4; 92 93 typedef void (*VP8BlockCopy)(const uint8_t* src, uint8_t* dst); 94 extern VP8BlockCopy VP8Copy4x4; 95 extern VP8BlockCopy VP8Copy16x8; 96 // Quantization 97 struct VP8Matrix; // forward declaration 98 typedef int (*VP8QuantizeBlock)(int16_t in[16], int16_t out[16], 99 const struct VP8Matrix* const mtx); 100 // Same as VP8QuantizeBlock, but quantizes two consecutive blocks. 101 typedef int (*VP8Quantize2Blocks)(int16_t in[32], int16_t out[32], 102 const struct VP8Matrix* const mtx); 103 104 extern VP8QuantizeBlock VP8EncQuantizeBlock; 105 extern VP8Quantize2Blocks VP8EncQuantize2Blocks; 106 107 // specific to 2nd transform: 108 typedef int (*VP8QuantizeBlockWHT)(int16_t in[16], int16_t out[16], 109 const struct VP8Matrix* const mtx); 110 extern VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT; 111 112 extern const int VP8DspScan[16 + 4 + 4]; 113 114 // Collect histogram for susceptibility calculation. 115 #define MAX_COEFF_THRESH 31 // size of histogram used by CollectHistogram. 116 typedef struct { 117 // We only need to store max_value and last_non_zero, not the distribution. 118 int max_value; 119 int last_non_zero; 120 } VP8Histogram; 121 typedef void (*VP8CHisto)(const uint8_t* ref, const uint8_t* pred, 122 int start_block, int end_block, 123 VP8Histogram* const histo); 124 extern VP8CHisto VP8CollectHistogram; 125 // General-purpose util function to help VP8CollectHistogram(). 126 void VP8SetHistogramData(const int distribution[MAX_COEFF_THRESH + 1], 127 VP8Histogram* const histo); 128 129 // must be called before using any of the above 130 void VP8EncDspInit(void); 131 132 //------------------------------------------------------------------------------ 133 // cost functions (encoding) 134 135 extern const uint16_t VP8EntropyCost[256]; // 8bit fixed-point log(p) 136 // approximate cost per level: 137 extern const uint16_t VP8LevelFixedCosts[2047 /*MAX_LEVEL*/ + 1]; 138 extern const uint8_t VP8EncBands[16 + 1]; 139 140 struct VP8Residual; 141 typedef void (*VP8SetResidualCoeffsFunc)(const int16_t* const coeffs, 142 struct VP8Residual* const res); 143 extern VP8SetResidualCoeffsFunc VP8SetResidualCoeffs; 144 145 // Cost calculation function. 146 typedef int (*VP8GetResidualCostFunc)(int ctx0, 147 const struct VP8Residual* const res); 148 extern VP8GetResidualCostFunc VP8GetResidualCost; 149 150 // must be called before anything using the above 151 void VP8EncDspCostInit(void); 152 153 //------------------------------------------------------------------------------ 154 // SSIM / PSNR utils 155 156 // struct for accumulating statistical moments 157 typedef struct { 158 uint32_t w; // sum(w_i) : sum of weights 159 uint32_t xm, ym; // sum(w_i * x_i), sum(w_i * y_i) 160 uint32_t xxm, xym, yym; // sum(w_i * x_i * x_i), etc. 161 } VP8DistoStats; 162 163 // Compute the final SSIM value 164 // The non-clipped version assumes stats->w = (2 * VP8_SSIM_KERNEL + 1)^2. 165 double VP8SSIMFromStats(const VP8DistoStats* const stats); 166 double VP8SSIMFromStatsClipped(const VP8DistoStats* const stats); 167 168 #define VP8_SSIM_KERNEL 3 // total size of the kernel: 2 * VP8_SSIM_KERNEL + 1 169 typedef double (*VP8SSIMGetClippedFunc)(const uint8_t* src1, int stride1, 170 const uint8_t* src2, int stride2, 171 int xo, int yo, // center position 172 int W, int H); // plane dimension 173 174 #if !defined(WEBP_REDUCE_SIZE) 175 // This version is called with the guarantee that you can load 8 bytes and 176 // 8 rows at offset src1 and src2 177 typedef double (*VP8SSIMGetFunc)(const uint8_t* src1, int stride1, 178 const uint8_t* src2, int stride2); 179 180 extern VP8SSIMGetFunc VP8SSIMGet; // unclipped / unchecked 181 extern VP8SSIMGetClippedFunc VP8SSIMGetClipped; // with clipping 182 #endif 183 184 #if !defined(WEBP_DISABLE_STATS) 185 typedef uint32_t (*VP8AccumulateSSEFunc)(const uint8_t* src1, 186 const uint8_t* src2, int len); 187 extern VP8AccumulateSSEFunc VP8AccumulateSSE; 188 #endif 189 190 // must be called before using any of the above directly 191 void VP8SSIMDspInit(void); 192 193 //------------------------------------------------------------------------------ 194 // Decoding 195 196 typedef void (*VP8DecIdct)(const int16_t* coeffs, uint8_t* dst); 197 // when doing two transforms, coeffs is actually int16_t[2][16]. 198 typedef void (*VP8DecIdct2)(const int16_t* coeffs, uint8_t* dst, int do_two); 199 extern VP8DecIdct2 VP8Transform; 200 extern VP8DecIdct VP8TransformAC3; 201 extern VP8DecIdct VP8TransformUV; 202 extern VP8DecIdct VP8TransformDC; 203 extern VP8DecIdct VP8TransformDCUV; 204 extern VP8WHT VP8TransformWHT; 205 206 #define WEBP_TRANSFORM_AC3_C1 20091 207 #define WEBP_TRANSFORM_AC3_C2 35468 208 #define WEBP_TRANSFORM_AC3_MUL1(a) ((((a) * WEBP_TRANSFORM_AC3_C1) >> 16) + (a)) 209 #define WEBP_TRANSFORM_AC3_MUL2(a) (((a) * WEBP_TRANSFORM_AC3_C2) >> 16) 210 211 // *dst is the destination block, with stride BPS. Boundary samples are 212 // assumed accessible when needed. 213 typedef void (*VP8PredFunc)(uint8_t* dst); 214 extern VP8PredFunc VP8PredLuma16[/* NUM_B_DC_MODES */]; 215 extern VP8PredFunc VP8PredChroma8[/* NUM_B_DC_MODES */]; 216 extern VP8PredFunc VP8PredLuma4[/* NUM_BMODES */]; 217 218 // clipping tables (for filtering) 219 extern const int8_t* const VP8ksclip1; // clips [-1020, 1020] to [-128, 127] 220 extern const int8_t* const VP8ksclip2; // clips [-112, 112] to [-16, 15] 221 extern const uint8_t* const VP8kclip1; // clips [-255,511] to [0,255] 222 extern const uint8_t* const VP8kabs0; // abs(x) for x in [-255,255] 223 // must be called first 224 void VP8InitClipTables(void); 225 226 // simple filter (only for luma) 227 typedef void (*VP8SimpleFilterFunc)(uint8_t* p, int stride, int thresh); 228 extern VP8SimpleFilterFunc VP8SimpleVFilter16; 229 extern VP8SimpleFilterFunc VP8SimpleHFilter16; 230 extern VP8SimpleFilterFunc VP8SimpleVFilter16i; // filter 3 inner edges 231 extern VP8SimpleFilterFunc VP8SimpleHFilter16i; 232 233 // regular filter (on both macroblock edges and inner edges) 234 typedef void (*VP8LumaFilterFunc)(uint8_t* luma, int stride, 235 int thresh, int ithresh, int hev_t); 236 typedef void (*VP8ChromaFilterFunc)(uint8_t* u, uint8_t* v, int stride, 237 int thresh, int ithresh, int hev_t); 238 // on outer edge 239 extern VP8LumaFilterFunc VP8VFilter16; 240 extern VP8LumaFilterFunc VP8HFilter16; 241 extern VP8ChromaFilterFunc VP8VFilter8; 242 extern VP8ChromaFilterFunc VP8HFilter8; 243 244 // on inner edge 245 extern VP8LumaFilterFunc VP8VFilter16i; // filtering 3 inner edges altogether 246 extern VP8LumaFilterFunc VP8HFilter16i; 247 extern VP8ChromaFilterFunc VP8VFilter8i; // filtering u and v altogether 248 extern VP8ChromaFilterFunc VP8HFilter8i; 249 250 // Dithering. Combines dithering values (centered around 128) with dst[], 251 // according to: dst[] = clip(dst[] + (((dither[]-128) + 8) >> 4) 252 #define VP8_DITHER_DESCALE 4 253 #define VP8_DITHER_DESCALE_ROUNDER (1 << (VP8_DITHER_DESCALE - 1)) 254 #define VP8_DITHER_AMP_BITS 7 255 #define VP8_DITHER_AMP_CENTER (1 << VP8_DITHER_AMP_BITS) 256 extern void (*VP8DitherCombine8x8)(const uint8_t* dither, uint8_t* dst, 257 int dst_stride); 258 259 // must be called before anything using the above 260 void VP8DspInit(void); 261 262 //------------------------------------------------------------------------------ 263 // WebP I/O 264 265 #define FANCY_UPSAMPLING // undefined to remove fancy upsampling support 266 267 // Convert a pair of y/u/v lines together to the output rgb/a colorspace. 268 // bottom_y can be NULL if only one line of output is needed (at top/bottom). 269 typedef void (*WebPUpsampleLinePairFunc)( 270 const uint8_t* top_y, const uint8_t* bottom_y, 271 const uint8_t* top_u, const uint8_t* top_v, 272 const uint8_t* cur_u, const uint8_t* cur_v, 273 uint8_t* top_dst, uint8_t* bottom_dst, int len); 274 275 #ifdef FANCY_UPSAMPLING 276 277 // Fancy upsampling functions to convert YUV to RGB(A) modes 278 extern WebPUpsampleLinePairFunc WebPUpsamplers[/* MODE_LAST */]; 279 280 #endif // FANCY_UPSAMPLING 281 282 // Per-row point-sampling methods. 283 typedef void (*WebPSamplerRowFunc)(const uint8_t* y, 284 const uint8_t* u, const uint8_t* v, 285 uint8_t* dst, int len); 286 // Generic function to apply 'WebPSamplerRowFunc' to the whole plane: 287 void WebPSamplerProcessPlane(const uint8_t* y, int y_stride, 288 const uint8_t* u, const uint8_t* v, int uv_stride, 289 uint8_t* dst, int dst_stride, 290 int width, int height, WebPSamplerRowFunc func); 291 292 // Sampling functions to convert rows of YUV to RGB(A) 293 extern WebPSamplerRowFunc WebPSamplers[/* MODE_LAST */]; 294 295 // General function for converting two lines of ARGB or RGBA. 296 // 'alpha_is_last' should be true if 0xff000000 is stored in memory as 297 // as 0x00, 0x00, 0x00, 0xff (little endian). 298 WebPUpsampleLinePairFunc WebPGetLinePairConverter(int alpha_is_last); 299 300 // YUV444->RGB converters 301 typedef void (*WebPYUV444Converter)(const uint8_t* y, 302 const uint8_t* u, const uint8_t* v, 303 uint8_t* dst, int len); 304 305 extern WebPYUV444Converter WebPYUV444Converters[/* MODE_LAST */]; 306 307 // Must be called before using the WebPUpsamplers[] (and for premultiplied 308 // colorspaces like rgbA, rgbA4444, etc) 309 void WebPInitUpsamplers(void); 310 // Must be called before using WebPSamplers[] 311 void WebPInitSamplers(void); 312 // Must be called before using WebPYUV444Converters[] 313 void WebPInitYUV444Converters(void); 314 315 //------------------------------------------------------------------------------ 316 // ARGB -> YUV converters 317 318 // Convert ARGB samples to luma Y. 319 extern void (*WebPConvertARGBToY)(const uint32_t* argb, uint8_t* y, int width); 320 // Convert ARGB samples to U/V with downsampling. do_store should be '1' for 321 // even lines and '0' for odd ones. 'src_width' is the original width, not 322 // the U/V one. 323 extern void (*WebPConvertARGBToUV)(const uint32_t* argb, uint8_t* u, uint8_t* v, 324 int src_width, int do_store); 325 326 // Convert a row of accumulated (four-values) of rgba32 toward U/V 327 extern void (*WebPConvertRGBA32ToUV)(const uint16_t* rgb, 328 uint8_t* u, uint8_t* v, int width); 329 330 // Convert RGB or BGR to Y 331 extern void (*WebPConvertRGB24ToY)(const uint8_t* rgb, uint8_t* y, int width); 332 extern void (*WebPConvertBGR24ToY)(const uint8_t* bgr, uint8_t* y, int width); 333 334 // used for plain-C fallback. 335 extern void WebPConvertARGBToUV_C(const uint32_t* argb, uint8_t* u, uint8_t* v, 336 int src_width, int do_store); 337 extern void WebPConvertRGBA32ToUV_C(const uint16_t* rgb, 338 uint8_t* u, uint8_t* v, int width); 339 340 // Must be called before using the above. 341 void WebPInitConvertARGBToYUV(void); 342 343 //------------------------------------------------------------------------------ 344 // Rescaler 345 346 struct WebPRescaler; 347 348 // Import a row of data and save its contribution in the rescaler. 349 // 'channel' denotes the channel number to be imported. 'Expand' corresponds to 350 // the wrk->x_expand case. Otherwise, 'Shrink' is to be used. 351 typedef void (*WebPRescalerImportRowFunc)(struct WebPRescaler* const wrk, 352 const uint8_t* src); 353 354 extern WebPRescalerImportRowFunc WebPRescalerImportRowExpand; 355 extern WebPRescalerImportRowFunc WebPRescalerImportRowShrink; 356 357 // Export one row (starting at x_out position) from rescaler. 358 // 'Expand' corresponds to the wrk->y_expand case. 359 // Otherwise 'Shrink' is to be used 360 typedef void (*WebPRescalerExportRowFunc)(struct WebPRescaler* const wrk); 361 extern WebPRescalerExportRowFunc WebPRescalerExportRowExpand; 362 extern WebPRescalerExportRowFunc WebPRescalerExportRowShrink; 363 364 // Plain-C implementation, as fall-back. 365 extern void WebPRescalerImportRowExpand_C(struct WebPRescaler* const wrk, 366 const uint8_t* src); 367 extern void WebPRescalerImportRowShrink_C(struct WebPRescaler* const wrk, 368 const uint8_t* src); 369 extern void WebPRescalerExportRowExpand_C(struct WebPRescaler* const wrk); 370 extern void WebPRescalerExportRowShrink_C(struct WebPRescaler* const wrk); 371 372 // Main entry calls: 373 extern void WebPRescalerImportRow(struct WebPRescaler* const wrk, 374 const uint8_t* src); 375 // Export one row (starting at x_out position) from rescaler. 376 extern void WebPRescalerExportRow(struct WebPRescaler* const wrk); 377 378 // Must be called first before using the above. 379 void WebPRescalerDspInit(void); 380 381 //------------------------------------------------------------------------------ 382 // Utilities for processing transparent channel. 383 384 // Apply alpha pre-multiply on an rgba, bgra or argb plane of size w * h. 385 // alpha_first should be 0 for argb, 1 for rgba or bgra (where alpha is last). 386 extern void (*WebPApplyAlphaMultiply)( 387 uint8_t* rgba, int alpha_first, int w, int h, int stride); 388 389 // Same, buf specifically for RGBA4444 format 390 extern void (*WebPApplyAlphaMultiply4444)( 391 uint8_t* rgba4444, int w, int h, int stride); 392 393 // Dispatch the values from alpha[] plane to the ARGB destination 'dst'. 394 // Returns true if alpha[] plane has non-trivial values different from 0xff. 395 extern int (*WebPDispatchAlpha)(const uint8_t* WEBP_RESTRICT alpha, 396 int alpha_stride, int width, int height, 397 uint8_t* WEBP_RESTRICT dst, int dst_stride); 398 399 // Transfer packed 8b alpha[] values to green channel in dst[], zero'ing the 400 // A/R/B values. 'dst_stride' is the stride for dst[] in uint32_t units. 401 extern void (*WebPDispatchAlphaToGreen)(const uint8_t* WEBP_RESTRICT alpha, 402 int alpha_stride, int width, int height, 403 uint32_t* WEBP_RESTRICT dst, 404 int dst_stride); 405 406 // Extract the alpha values from 32b values in argb[] and pack them into alpha[] 407 // (this is the opposite of WebPDispatchAlpha). 408 // Returns true if there's only trivial 0xff alpha values. 409 extern int (*WebPExtractAlpha)(const uint8_t* WEBP_RESTRICT argb, 410 int argb_stride, int width, int height, 411 uint8_t* WEBP_RESTRICT alpha, 412 int alpha_stride); 413 414 // Extract the green values from 32b values in argb[] and pack them into alpha[] 415 // (this is the opposite of WebPDispatchAlphaToGreen). 416 extern void (*WebPExtractGreen)(const uint32_t* WEBP_RESTRICT argb, 417 uint8_t* WEBP_RESTRICT alpha, int size); 418 419 // Pre-Multiply operation transforms x into x * A / 255 (where x=Y,R,G or B). 420 // Un-Multiply operation transforms x into x * 255 / A. 421 422 // Pre-Multiply or Un-Multiply (if 'inverse' is true) argb values in a row. 423 extern void (*WebPMultARGBRow)(uint32_t* const ptr, int width, int inverse); 424 425 // Same a WebPMultARGBRow(), but for several rows. 426 void WebPMultARGBRows(uint8_t* ptr, int stride, int width, int num_rows, 427 int inverse); 428 429 // Same for a row of single values, with side alpha values. 430 extern void (*WebPMultRow)(uint8_t* WEBP_RESTRICT const ptr, 431 const uint8_t* WEBP_RESTRICT const alpha, 432 int width, int inverse); 433 434 // Same a WebPMultRow(), but for several 'num_rows' rows. 435 void WebPMultRows(uint8_t* WEBP_RESTRICT ptr, int stride, 436 const uint8_t* WEBP_RESTRICT alpha, int alpha_stride, 437 int width, int num_rows, int inverse); 438 439 // Plain-C versions, used as fallback by some implementations. 440 void WebPMultRow_C(uint8_t* WEBP_RESTRICT const ptr, 441 const uint8_t* WEBP_RESTRICT const alpha, 442 int width, int inverse); 443 void WebPMultARGBRow_C(uint32_t* const ptr, int width, int inverse); 444 445 #ifdef WORDS_BIGENDIAN 446 // ARGB packing function: a/r/g/b input is rgba or bgra order. 447 extern void (*WebPPackARGB)(const uint8_t* WEBP_RESTRICT a, 448 const uint8_t* WEBP_RESTRICT r, 449 const uint8_t* WEBP_RESTRICT g, 450 const uint8_t* WEBP_RESTRICT b, 451 int len, uint32_t* WEBP_RESTRICT out); 452 #endif 453 454 // RGB packing function. 'step' can be 3 or 4. r/g/b input is rgb or bgr order. 455 extern void (*WebPPackRGB)(const uint8_t* WEBP_RESTRICT r, 456 const uint8_t* WEBP_RESTRICT g, 457 const uint8_t* WEBP_RESTRICT b, 458 int len, int step, uint32_t* WEBP_RESTRICT out); 459 460 // This function returns true if src[i] contains a value different from 0xff. 461 extern int (*WebPHasAlpha8b)(const uint8_t* src, int length); 462 // This function returns true if src[4*i] contains a value different from 0xff. 463 extern int (*WebPHasAlpha32b)(const uint8_t* src, int length); 464 // replaces transparent values in src[] by 'color'. 465 extern void (*WebPAlphaReplace)(uint32_t* src, int length, uint32_t color); 466 467 // To be called first before using the above. 468 void WebPInitAlphaProcessing(void); 469 470 //------------------------------------------------------------------------------ 471 // Filter functions 472 473 typedef enum { // Filter types. 474 WEBP_FILTER_NONE = 0, 475 WEBP_FILTER_HORIZONTAL, 476 WEBP_FILTER_VERTICAL, 477 WEBP_FILTER_GRADIENT, 478 WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1, // end marker 479 WEBP_FILTER_BEST, // meta-types 480 WEBP_FILTER_FAST 481 } WEBP_FILTER_TYPE; 482 483 typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height, 484 int stride, uint8_t* out); 485 // In-place un-filtering. 486 // Warning! 'prev_line' pointer can be equal to 'cur_line' or 'preds'. 487 typedef void (*WebPUnfilterFunc)(const uint8_t* prev_line, const uint8_t* preds, 488 uint8_t* cur_line, int width); 489 490 // Filter the given data using the given predictor. 491 // 'in' corresponds to a 2-dimensional pixel array of size (stride * height) 492 // in raster order. 493 // 'stride' is number of bytes per scan line (with possible padding). 494 // 'out' should be pre-allocated. 495 extern WebPFilterFunc WebPFilters[WEBP_FILTER_LAST]; 496 497 // In-place reconstruct the original data from the given filtered data. 498 // The reconstruction will be done for 'num_rows' rows starting from 'row' 499 // (assuming rows upto 'row - 1' are already reconstructed). 500 extern WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST]; 501 502 // To be called first before using the above. 503 void VP8FiltersInit(void); 504 505 #ifdef __cplusplus 506 } // extern "C" 507 #endif 508 509 #endif // WEBP_DSP_DSP_H_ 510