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 // WebP encoder: internal header. 11 // 12 // Author: Skal (pascal.massimino (at) gmail.com) 13 14 #ifndef WEBP_ENC_VP8I_ENC_H_ 15 #define WEBP_ENC_VP8I_ENC_H_ 16 17 #include <string.h> // for memcpy() 18 #include "src/dec/common_dec.h" 19 #include "src/dsp/dsp.h" 20 #include "src/utils/bit_writer_utils.h" 21 #include "src/utils/thread_utils.h" 22 #include "src/utils/utils.h" 23 #include "src/webp/encode.h" 24 25 #ifdef __cplusplus 26 extern "C" { 27 #endif 28 29 //------------------------------------------------------------------------------ 30 // Various defines and enums 31 32 // version numbers 33 #define ENC_MAJ_VERSION 1 34 #define ENC_MIN_VERSION 0 35 #define ENC_REV_VERSION 2 36 37 enum { MAX_LF_LEVELS = 64, // Maximum loop filter level 38 MAX_VARIABLE_LEVEL = 67, // last (inclusive) level with variable cost 39 MAX_LEVEL = 2047 // max level (note: max codable is 2047 + 67) 40 }; 41 42 typedef enum { // Rate-distortion optimization levels 43 RD_OPT_NONE = 0, // no rd-opt 44 RD_OPT_BASIC = 1, // basic scoring (no trellis) 45 RD_OPT_TRELLIS = 2, // perform trellis-quant on the final decision only 46 RD_OPT_TRELLIS_ALL = 3 // trellis-quant for every scoring (much slower) 47 } VP8RDLevel; 48 49 // YUV-cache parameters. Cache is 32-bytes wide (= one cacheline). 50 // The original or reconstructed samples can be accessed using VP8Scan[]. 51 // The predicted blocks can be accessed using offsets to yuv_p_ and 52 // the arrays VP8*ModeOffsets[]. 53 // * YUV Samples area (yuv_in_/yuv_out_/yuv_out2_) 54 // (see VP8Scan[] for accessing the blocks, along with 55 // Y_OFF_ENC/U_OFF_ENC/V_OFF_ENC): 56 // +----+----+ 57 // Y_OFF_ENC |YYYY|UUVV| 58 // U_OFF_ENC |YYYY|UUVV| 59 // V_OFF_ENC |YYYY|....| <- 25% wasted U/V area 60 // |YYYY|....| 61 // +----+----+ 62 // * Prediction area ('yuv_p_', size = PRED_SIZE_ENC) 63 // Intra16 predictions (16x16 block each, two per row): 64 // |I16DC16|I16TM16| 65 // |I16VE16|I16HE16| 66 // Chroma U/V predictions (16x8 block each, two per row): 67 // |C8DC8|C8TM8| 68 // |C8VE8|C8HE8| 69 // Intra 4x4 predictions (4x4 block each) 70 // |I4DC4 I4TM4 I4VE4 I4HE4|I4RD4 I4VR4 I4LD4 I4VL4| 71 // |I4HD4 I4HU4 I4TMP .....|.......................| <- ~31% wasted 72 #define YUV_SIZE_ENC (BPS * 16) 73 #define PRED_SIZE_ENC (32 * BPS + 16 * BPS + 8 * BPS) // I16+Chroma+I4 preds 74 #define Y_OFF_ENC (0) 75 #define U_OFF_ENC (16) 76 #define V_OFF_ENC (16 + 8) 77 78 extern const uint16_t VP8Scan[16]; 79 extern const uint16_t VP8UVModeOffsets[4]; 80 extern const uint16_t VP8I16ModeOffsets[4]; 81 extern const uint16_t VP8I4ModeOffsets[NUM_BMODES]; 82 83 // Layout of prediction blocks 84 // intra 16x16 85 #define I16DC16 (0 * 16 * BPS) 86 #define I16TM16 (I16DC16 + 16) 87 #define I16VE16 (1 * 16 * BPS) 88 #define I16HE16 (I16VE16 + 16) 89 // chroma 8x8, two U/V blocks side by side (hence: 16x8 each) 90 #define C8DC8 (2 * 16 * BPS) 91 #define C8TM8 (C8DC8 + 1 * 16) 92 #define C8VE8 (2 * 16 * BPS + 8 * BPS) 93 #define C8HE8 (C8VE8 + 1 * 16) 94 // intra 4x4 95 #define I4DC4 (3 * 16 * BPS + 0) 96 #define I4TM4 (I4DC4 + 4) 97 #define I4VE4 (I4DC4 + 8) 98 #define I4HE4 (I4DC4 + 12) 99 #define I4RD4 (I4DC4 + 16) 100 #define I4VR4 (I4DC4 + 20) 101 #define I4LD4 (I4DC4 + 24) 102 #define I4VL4 (I4DC4 + 28) 103 #define I4HD4 (3 * 16 * BPS + 4 * BPS) 104 #define I4HU4 (I4HD4 + 4) 105 #define I4TMP (I4HD4 + 8) 106 107 typedef int64_t score_t; // type used for scores, rate, distortion 108 // Note that MAX_COST is not the maximum allowed by sizeof(score_t), 109 // in order to allow overflowing computations. 110 #define MAX_COST ((score_t)0x7fffffffffffffLL) 111 112 #define QFIX 17 113 #define BIAS(b) ((b) << (QFIX - 8)) 114 // Fun fact: this is the _only_ line where we're actually being lossy and 115 // discarding bits. 116 static WEBP_INLINE int QUANTDIV(uint32_t n, uint32_t iQ, uint32_t B) { 117 return (int)((n * iQ + B) >> QFIX); 118 } 119 120 // Uncomment the following to remove token-buffer code: 121 // #define DISABLE_TOKEN_BUFFER 122 123 // quality below which error-diffusion is enabled 124 #define ERROR_DIFFUSION_QUALITY 98 125 126 //------------------------------------------------------------------------------ 127 // Headers 128 129 typedef uint32_t proba_t; // 16b + 16b 130 typedef uint8_t ProbaArray[NUM_CTX][NUM_PROBAS]; 131 typedef proba_t StatsArray[NUM_CTX][NUM_PROBAS]; 132 typedef uint16_t CostArray[NUM_CTX][MAX_VARIABLE_LEVEL + 1]; 133 typedef const uint16_t* (*CostArrayPtr)[NUM_CTX]; // for easy casting 134 typedef const uint16_t* CostArrayMap[16][NUM_CTX]; 135 typedef double LFStats[NUM_MB_SEGMENTS][MAX_LF_LEVELS]; // filter stats 136 137 typedef struct VP8Encoder VP8Encoder; 138 139 // segment features 140 typedef struct { 141 int num_segments_; // Actual number of segments. 1 segment only = unused. 142 int update_map_; // whether to update the segment map or not. 143 // must be 0 if there's only 1 segment. 144 int size_; // bit-cost for transmitting the segment map 145 } VP8EncSegmentHeader; 146 147 // Struct collecting all frame-persistent probabilities. 148 typedef struct { 149 uint8_t segments_[3]; // probabilities for segment tree 150 uint8_t skip_proba_; // final probability of being skipped. 151 ProbaArray coeffs_[NUM_TYPES][NUM_BANDS]; // 1056 bytes 152 StatsArray stats_[NUM_TYPES][NUM_BANDS]; // 4224 bytes 153 CostArray level_cost_[NUM_TYPES][NUM_BANDS]; // 13056 bytes 154 CostArrayMap remapped_costs_[NUM_TYPES]; // 1536 bytes 155 int dirty_; // if true, need to call VP8CalculateLevelCosts() 156 int use_skip_proba_; // Note: we always use skip_proba for now. 157 int nb_skip_; // number of skipped blocks 158 } VP8EncProba; 159 160 // Filter parameters. Not actually used in the code (we don't perform 161 // the in-loop filtering), but filled from user's config 162 typedef struct { 163 int simple_; // filtering type: 0=complex, 1=simple 164 int level_; // base filter level [0..63] 165 int sharpness_; // [0..7] 166 int i4x4_lf_delta_; // delta filter level for i4x4 relative to i16x16 167 } VP8EncFilterHeader; 168 169 //------------------------------------------------------------------------------ 170 // Informations about the macroblocks. 171 172 typedef struct { 173 // block type 174 unsigned int type_:2; // 0=i4x4, 1=i16x16 175 unsigned int uv_mode_:2; 176 unsigned int skip_:1; 177 unsigned int segment_:2; 178 uint8_t alpha_; // quantization-susceptibility 179 } VP8MBInfo; 180 181 typedef struct VP8Matrix { 182 uint16_t q_[16]; // quantizer steps 183 uint16_t iq_[16]; // reciprocals, fixed point. 184 uint32_t bias_[16]; // rounding bias 185 uint32_t zthresh_[16]; // value below which a coefficient is zeroed 186 uint16_t sharpen_[16]; // frequency boosters for slight sharpening 187 } VP8Matrix; 188 189 typedef struct { 190 VP8Matrix y1_, y2_, uv_; // quantization matrices 191 int alpha_; // quant-susceptibility, range [-127,127]. Zero is neutral. 192 // Lower values indicate a lower risk of blurriness. 193 int beta_; // filter-susceptibility, range [0,255]. 194 int quant_; // final segment quantizer. 195 int fstrength_; // final in-loop filtering strength 196 int max_edge_; // max edge delta (for filtering strength) 197 int min_disto_; // minimum distortion required to trigger filtering record 198 // reactivities 199 int lambda_i16_, lambda_i4_, lambda_uv_; 200 int lambda_mode_, lambda_trellis_, tlambda_; 201 int lambda_trellis_i16_, lambda_trellis_i4_, lambda_trellis_uv_; 202 203 // lambda values for distortion-based evaluation 204 score_t i4_penalty_; // penalty for using Intra4 205 } VP8SegmentInfo; 206 207 typedef int8_t DError[2 /* u/v */][2 /* top or left */]; 208 209 // Handy transient struct to accumulate score and info during RD-optimization 210 // and mode evaluation. 211 typedef struct { 212 score_t D, SD; // Distortion, spectral distortion 213 score_t H, R, score; // header bits, rate, score. 214 int16_t y_dc_levels[16]; // Quantized levels for luma-DC, luma-AC, chroma. 215 int16_t y_ac_levels[16][16]; 216 int16_t uv_levels[4 + 4][16]; 217 int mode_i16; // mode number for intra16 prediction 218 uint8_t modes_i4[16]; // mode numbers for intra4 predictions 219 int mode_uv; // mode number of chroma prediction 220 uint32_t nz; // non-zero blocks 221 int8_t derr[2][3]; // DC diffusion errors for U/V for blocks #1/2/3 222 } VP8ModeScore; 223 224 // Iterator structure to iterate through macroblocks, pointing to the 225 // right neighbouring data (samples, predictions, contexts, ...) 226 typedef struct { 227 int x_, y_; // current macroblock 228 uint8_t* yuv_in_; // input samples 229 uint8_t* yuv_out_; // output samples 230 uint8_t* yuv_out2_; // secondary buffer swapped with yuv_out_. 231 uint8_t* yuv_p_; // scratch buffer for prediction 232 VP8Encoder* enc_; // back-pointer 233 VP8MBInfo* mb_; // current macroblock 234 VP8BitWriter* bw_; // current bit-writer 235 uint8_t* preds_; // intra mode predictors (4x4 blocks) 236 uint32_t* nz_; // non-zero pattern 237 uint8_t i4_boundary_[37]; // 32+5 boundary samples needed by intra4x4 238 uint8_t* i4_top_; // pointer to the current top boundary sample 239 int i4_; // current intra4x4 mode being tested 240 int top_nz_[9]; // top-non-zero context. 241 int left_nz_[9]; // left-non-zero. left_nz[8] is independent. 242 uint64_t bit_count_[4][3]; // bit counters for coded levels. 243 uint64_t luma_bits_; // macroblock bit-cost for luma 244 uint64_t uv_bits_; // macroblock bit-cost for chroma 245 LFStats* lf_stats_; // filter stats (borrowed from enc_) 246 int do_trellis_; // if true, perform extra level optimisation 247 int count_down_; // number of mb still to be processed 248 int count_down0_; // starting counter value (for progress) 249 int percent0_; // saved initial progress percent 250 251 DError left_derr_; // left error diffusion (u/v) 252 DError *top_derr_; // top diffusion error - NULL if disabled 253 254 uint8_t* y_left_; // left luma samples (addressable from index -1 to 15). 255 uint8_t* u_left_; // left u samples (addressable from index -1 to 7) 256 uint8_t* v_left_; // left v samples (addressable from index -1 to 7) 257 258 uint8_t* y_top_; // top luma samples at position 'x_' 259 uint8_t* uv_top_; // top u/v samples at position 'x_', packed as 16 bytes 260 261 // memory for storing y/u/v_left_ 262 uint8_t yuv_left_mem_[17 + 16 + 16 + 8 + WEBP_ALIGN_CST]; 263 // memory for yuv_* 264 uint8_t yuv_mem_[3 * YUV_SIZE_ENC + PRED_SIZE_ENC + WEBP_ALIGN_CST]; 265 } VP8EncIterator; 266 267 // in iterator.c 268 // must be called first 269 void VP8IteratorInit(VP8Encoder* const enc, VP8EncIterator* const it); 270 // restart a scan 271 void VP8IteratorReset(VP8EncIterator* const it); 272 // reset iterator position to row 'y' 273 void VP8IteratorSetRow(VP8EncIterator* const it, int y); 274 // set count down (=number of iterations to go) 275 void VP8IteratorSetCountDown(VP8EncIterator* const it, int count_down); 276 // return true if iteration is finished 277 int VP8IteratorIsDone(const VP8EncIterator* const it); 278 // Import uncompressed samples from source. 279 // If tmp_32 is not NULL, import boundary samples too. 280 // tmp_32 is a 32-bytes scratch buffer that must be aligned in memory. 281 void VP8IteratorImport(VP8EncIterator* const it, uint8_t* const tmp_32); 282 // export decimated samples 283 void VP8IteratorExport(const VP8EncIterator* const it); 284 // go to next macroblock. Returns false if not finished. 285 int VP8IteratorNext(VP8EncIterator* const it); 286 // save the yuv_out_ boundary values to top_/left_ arrays for next iterations. 287 void VP8IteratorSaveBoundary(VP8EncIterator* const it); 288 // Report progression based on macroblock rows. Return 0 for user-abort request. 289 int VP8IteratorProgress(const VP8EncIterator* const it, 290 int final_delta_percent); 291 // Intra4x4 iterations 292 void VP8IteratorStartI4(VP8EncIterator* const it); 293 // returns true if not done. 294 int VP8IteratorRotateI4(VP8EncIterator* const it, 295 const uint8_t* const yuv_out); 296 297 // Non-zero context setup/teardown 298 void VP8IteratorNzToBytes(VP8EncIterator* const it); 299 void VP8IteratorBytesToNz(VP8EncIterator* const it); 300 301 // Helper functions to set mode properties 302 void VP8SetIntra16Mode(const VP8EncIterator* const it, int mode); 303 void VP8SetIntra4Mode(const VP8EncIterator* const it, const uint8_t* modes); 304 void VP8SetIntraUVMode(const VP8EncIterator* const it, int mode); 305 void VP8SetSkip(const VP8EncIterator* const it, int skip); 306 void VP8SetSegment(const VP8EncIterator* const it, int segment); 307 308 //------------------------------------------------------------------------------ 309 // Paginated token buffer 310 311 typedef struct VP8Tokens VP8Tokens; // struct details in token.c 312 313 typedef struct { 314 #if !defined(DISABLE_TOKEN_BUFFER) 315 VP8Tokens* pages_; // first page 316 VP8Tokens** last_page_; // last page 317 uint16_t* tokens_; // set to (*last_page_)->tokens_ 318 int left_; // how many free tokens left before the page is full 319 int page_size_; // number of tokens per page 320 #endif 321 int error_; // true in case of malloc error 322 } VP8TBuffer; 323 324 // initialize an empty buffer 325 void VP8TBufferInit(VP8TBuffer* const b, int page_size); 326 void VP8TBufferClear(VP8TBuffer* const b); // de-allocate pages memory 327 328 #if !defined(DISABLE_TOKEN_BUFFER) 329 330 // Finalizes bitstream when probabilities are known. 331 // Deletes the allocated token memory if final_pass is true. 332 int VP8EmitTokens(VP8TBuffer* const b, VP8BitWriter* const bw, 333 const uint8_t* const probas, int final_pass); 334 335 // record the coding of coefficients without knowing the probabilities yet 336 int VP8RecordCoeffTokens(int ctx, const struct VP8Residual* const res, 337 VP8TBuffer* const tokens); 338 339 // Estimate the final coded size given a set of 'probas'. 340 size_t VP8EstimateTokenSize(VP8TBuffer* const b, const uint8_t* const probas); 341 342 #endif // !DISABLE_TOKEN_BUFFER 343 344 //------------------------------------------------------------------------------ 345 // VP8Encoder 346 347 struct VP8Encoder { 348 const WebPConfig* config_; // user configuration and parameters 349 WebPPicture* pic_; // input / output picture 350 351 // headers 352 VP8EncFilterHeader filter_hdr_; // filtering information 353 VP8EncSegmentHeader segment_hdr_; // segment information 354 355 int profile_; // VP8's profile, deduced from Config. 356 357 // dimension, in macroblock units. 358 int mb_w_, mb_h_; 359 int preds_w_; // stride of the *preds_ prediction plane (=4*mb_w + 1) 360 361 // number of partitions (1, 2, 4 or 8 = MAX_NUM_PARTITIONS) 362 int num_parts_; 363 364 // per-partition boolean decoders. 365 VP8BitWriter bw_; // part0 366 VP8BitWriter parts_[MAX_NUM_PARTITIONS]; // token partitions 367 VP8TBuffer tokens_; // token buffer 368 369 int percent_; // for progress 370 371 // transparency blob 372 int has_alpha_; 373 uint8_t* alpha_data_; // non-NULL if transparency is present 374 uint32_t alpha_data_size_; 375 WebPWorker alpha_worker_; 376 377 // quantization info (one set of DC/AC dequant factor per segment) 378 VP8SegmentInfo dqm_[NUM_MB_SEGMENTS]; 379 int base_quant_; // nominal quantizer value. Only used 380 // for relative coding of segments' quant. 381 int alpha_; // global susceptibility (<=> complexity) 382 int uv_alpha_; // U/V quantization susceptibility 383 // global offset of quantizers, shared by all segments 384 int dq_y1_dc_; 385 int dq_y2_dc_, dq_y2_ac_; 386 int dq_uv_dc_, dq_uv_ac_; 387 388 // probabilities and statistics 389 VP8EncProba proba_; 390 uint64_t sse_[4]; // sum of Y/U/V/A squared errors for all macroblocks 391 uint64_t sse_count_; // pixel count for the sse_[] stats 392 int coded_size_; 393 int residual_bytes_[3][4]; 394 int block_count_[3]; 395 396 // quality/speed settings 397 int method_; // 0=fastest, 6=best/slowest. 398 VP8RDLevel rd_opt_level_; // Deduced from method_. 399 int max_i4_header_bits_; // partition #0 safeness factor 400 int mb_header_limit_; // rough limit for header bits per MB 401 int thread_level_; // derived from config->thread_level 402 int do_search_; // derived from config->target_XXX 403 int use_tokens_; // if true, use token buffer 404 405 // Memory 406 VP8MBInfo* mb_info_; // contextual macroblock infos (mb_w_ + 1) 407 uint8_t* preds_; // predictions modes: (4*mb_w+1) * (4*mb_h+1) 408 uint32_t* nz_; // non-zero bit context: mb_w+1 409 uint8_t* y_top_; // top luma samples. 410 uint8_t* uv_top_; // top u/v samples. 411 // U and V are packed into 16 bytes (8 U + 8 V) 412 LFStats* lf_stats_; // autofilter stats (if NULL, autofilter is off) 413 DError* top_derr_; // diffusion error (NULL if disabled) 414 }; 415 416 //------------------------------------------------------------------------------ 417 // internal functions. Not public. 418 419 // in tree.c 420 extern const uint8_t VP8CoeffsProba0[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS]; 421 extern const uint8_t 422 VP8CoeffsUpdateProba[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS]; 423 // Reset the token probabilities to their initial (default) values 424 void VP8DefaultProbas(VP8Encoder* const enc); 425 // Write the token probabilities 426 void VP8WriteProbas(VP8BitWriter* const bw, const VP8EncProba* const probas); 427 // Writes the partition #0 modes (that is: all intra modes) 428 void VP8CodeIntraModes(VP8Encoder* const enc); 429 430 // in syntax.c 431 // Generates the final bitstream by coding the partition0 and headers, 432 // and appending an assembly of all the pre-coded token partitions. 433 // Return true if everything is ok. 434 int VP8EncWrite(VP8Encoder* const enc); 435 // Release memory allocated for bit-writing in VP8EncLoop & seq. 436 void VP8EncFreeBitWriters(VP8Encoder* const enc); 437 438 // in frame.c 439 extern const uint8_t VP8Cat3[]; 440 extern const uint8_t VP8Cat4[]; 441 extern const uint8_t VP8Cat5[]; 442 extern const uint8_t VP8Cat6[]; 443 444 // Form all the four Intra16x16 predictions in the yuv_p_ cache 445 void VP8MakeLuma16Preds(const VP8EncIterator* const it); 446 // Form all the four Chroma8x8 predictions in the yuv_p_ cache 447 void VP8MakeChroma8Preds(const VP8EncIterator* const it); 448 // Form all the ten Intra4x4 predictions in the yuv_p_ cache 449 // for the 4x4 block it->i4_ 450 void VP8MakeIntra4Preds(const VP8EncIterator* const it); 451 // Rate calculation 452 int VP8GetCostLuma16(VP8EncIterator* const it, const VP8ModeScore* const rd); 453 int VP8GetCostLuma4(VP8EncIterator* const it, const int16_t levels[16]); 454 int VP8GetCostUV(VP8EncIterator* const it, const VP8ModeScore* const rd); 455 // Main coding calls 456 int VP8EncLoop(VP8Encoder* const enc); 457 int VP8EncTokenLoop(VP8Encoder* const enc); 458 459 // in webpenc.c 460 // Assign an error code to a picture. Return false for convenience. 461 int WebPEncodingSetError(const WebPPicture* const pic, WebPEncodingError error); 462 int WebPReportProgress(const WebPPicture* const pic, 463 int percent, int* const percent_store); 464 465 // in analysis.c 466 // Main analysis loop. Decides the segmentations and complexity. 467 // Assigns a first guess for Intra16 and uvmode_ prediction modes. 468 int VP8EncAnalyze(VP8Encoder* const enc); 469 470 // in quant.c 471 // Sets up segment's quantization values, base_quant_ and filter strengths. 472 void VP8SetSegmentParams(VP8Encoder* const enc, float quality); 473 // Pick best modes and fills the levels. Returns true if skipped. 474 int VP8Decimate(VP8EncIterator* const it, VP8ModeScore* const rd, 475 VP8RDLevel rd_opt); 476 477 // in alpha.c 478 void VP8EncInitAlpha(VP8Encoder* const enc); // initialize alpha compression 479 int VP8EncStartAlpha(VP8Encoder* const enc); // start alpha coding process 480 int VP8EncFinishAlpha(VP8Encoder* const enc); // finalize compressed data 481 int VP8EncDeleteAlpha(VP8Encoder* const enc); // delete compressed data 482 483 // autofilter 484 void VP8InitFilter(VP8EncIterator* const it); 485 void VP8StoreFilterStats(VP8EncIterator* const it); 486 void VP8AdjustFilterStrength(VP8EncIterator* const it); 487 488 // returns the approximate filtering strength needed to smooth a edge 489 // step of 'delta', given a sharpness parameter 'sharpness'. 490 int VP8FilterStrengthFromDelta(int sharpness, int delta); 491 492 // misc utils for picture_*.c: 493 494 // Remove reference to the ARGB/YUVA buffer (doesn't free anything). 495 void WebPPictureResetBuffers(WebPPicture* const picture); 496 497 // Allocates ARGB buffer of given dimension (previous one is always free'd). 498 // Preserves the YUV(A) buffer. Returns false in case of error (invalid param, 499 // out-of-memory). 500 int WebPPictureAllocARGB(WebPPicture* const picture, int width, int height); 501 502 // Allocates YUVA buffer of given dimension (previous one is always free'd). 503 // Uses picture->csp to determine whether an alpha buffer is needed. 504 // Preserves the ARGB buffer. 505 // Returns false in case of error (invalid param, out-of-memory). 506 int WebPPictureAllocYUVA(WebPPicture* const picture, int width, int height); 507 508 // Clean-up the RGB samples under fully transparent area, to help lossless 509 // compressibility (no guarantee, though). Assumes that pic->use_argb is true. 510 void WebPCleanupTransparentAreaLossless(WebPPicture* const pic); 511 512 //------------------------------------------------------------------------------ 513 514 #ifdef __cplusplus 515 } // extern "C" 516 #endif 517 518 #endif // WEBP_ENC_VP8I_ENC_H_ 519
