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@gmail.com)
13 
14 #ifndef WEBP_ENC_VP8ENCI_H_
15 #define WEBP_ENC_VP8ENCI_H_
16 
17 #include <string.h>     // for memcpy()
18 #include "../webp/encode.h"
19 #include "../dsp/dsp.h"
20 #include "../utils/bit_writer.h"
21 #include "../utils/thread.h"
22 
23 #if defined(__cplusplus) || defined(c_plusplus)
24 extern "C" {
25 #endif
26 
27 //------------------------------------------------------------------------------
28 // Various defines and enums
29 
30 // version numbers
31 #define ENC_MAJ_VERSION 0
32 #define ENC_MIN_VERSION 3
33 #define ENC_REV_VERSION 1
34 
35 // intra prediction modes
36 enum { B_DC_PRED = 0,   // 4x4 modes
37        B_TM_PRED = 1,
38        B_VE_PRED = 2,
39        B_HE_PRED = 3,
40        B_RD_PRED = 4,
41        B_VR_PRED = 5,
42        B_LD_PRED = 6,
43        B_VL_PRED = 7,
44        B_HD_PRED = 8,
45        B_HU_PRED = 9,
46        NUM_BMODES = B_HU_PRED + 1 - B_DC_PRED,  // = 10
47 
48        // Luma16 or UV modes
49        DC_PRED = B_DC_PRED, V_PRED = B_VE_PRED,
50        H_PRED = B_HE_PRED, TM_PRED = B_TM_PRED,
51        NUM_PRED_MODES = 4
52      };
53 
54 enum { NUM_MB_SEGMENTS = 4,
55        MAX_NUM_PARTITIONS = 8,
56        NUM_TYPES = 4,   // 0: i16-AC,  1: i16-DC,  2:chroma-AC,  3:i4-AC
57        NUM_BANDS = 8,
58        NUM_CTX = 3,
59        NUM_PROBAS = 11,
60        MAX_LF_LEVELS = 64,       // Maximum loop filter level
61        MAX_VARIABLE_LEVEL = 67,  // last (inclusive) level with variable cost
62        MAX_LEVEL = 2047          // max level (note: max codable is 2047 + 67)
63      };
64 
65 typedef enum {   // Rate-distortion optimization levels
66   RD_OPT_NONE        = 0,  // no rd-opt
67   RD_OPT_BASIC       = 1,  // basic scoring (no trellis)
68   RD_OPT_TRELLIS     = 2,  // perform trellis-quant on the final decision only
69   RD_OPT_TRELLIS_ALL = 3   // trellis-quant for every scoring (much slower)
70 } VP8RDLevel;
71 
72 // YUV-cache parameters. Cache is 16-pixels wide.
73 // The original or reconstructed samples can be accessed using VP8Scan[]
74 // The predicted blocks can be accessed using offsets to yuv_p_ and
75 // the arrays VP8*ModeOffsets[];
76 //         +----+      YUV Samples area. See VP8Scan[] for accessing the blocks.
77 //  Y_OFF  |YYYY| <- original samples  (enc->yuv_in_)
78 //         |YYYY|
79 //         |YYYY|
80 //         |YYYY|
81 //  U_OFF  |UUVV| V_OFF  (=U_OFF + 8)
82 //         |UUVV|
83 //         +----+
84 //  Y_OFF  |YYYY| <- compressed/decoded samples  ('yuv_out_')
85 //         |YYYY|    There are two buffers like this ('yuv_out_'/'yuv_out2_')
86 //         |YYYY|
87 //         |YYYY|
88 //  U_OFF  |UUVV| V_OFF
89 //         |UUVV|
90 //          x2 (for yuv_out2_)
91 //         +----+     Prediction area ('yuv_p_', size = PRED_SIZE)
92 // I16DC16 |YYYY|  Intra16 predictions (16x16 block each)
93 //         |YYYY|
94 //         |YYYY|
95 //         |YYYY|
96 // I16TM16 |YYYY|
97 //         |YYYY|
98 //         |YYYY|
99 //         |YYYY|
100 // I16VE16 |YYYY|
101 //         |YYYY|
102 //         |YYYY|
103 //         |YYYY|
104 // I16HE16 |YYYY|
105 //         |YYYY|
106 //         |YYYY|
107 //         |YYYY|
108 //         +----+  Chroma U/V predictions (16x8 block each)
109 // C8DC8   |UUVV|
110 //         |UUVV|
111 // C8TM8   |UUVV|
112 //         |UUVV|
113 // C8VE8   |UUVV|
114 //         |UUVV|
115 // C8HE8   |UUVV|
116 //         |UUVV|
117 //         +----+  Intra 4x4 predictions (4x4 block each)
118 //         |YYYY| I4DC4 I4TM4 I4VE4 I4HE4
119 //         |YYYY| I4RD4 I4VR4 I4LD4 I4VL4
120 //         |YY..| I4HD4 I4HU4 I4TMP
121 //         +----+
122 #define BPS       16   // this is the common stride
123 #define Y_SIZE   (BPS * 16)
124 #define UV_SIZE  (BPS * 8)
125 #define YUV_SIZE (Y_SIZE + UV_SIZE)
126 #define PRED_SIZE (6 * 16 * BPS + 12 * BPS)
127 #define Y_OFF    (0)
128 #define U_OFF    (Y_SIZE)
129 #define V_OFF    (U_OFF + 8)
130 #define ALIGN_CST 15
131 #define DO_ALIGN(PTR) ((uintptr_t)((PTR) + ALIGN_CST) & ~ALIGN_CST)
132 
133 extern const int VP8Scan[16 + 4 + 4];           // in quant.c
134 extern const int VP8UVModeOffsets[4];           // in analyze.c
135 extern const int VP8I16ModeOffsets[4];
136 extern const int VP8I4ModeOffsets[NUM_BMODES];
137 
138 // Layout of prediction blocks
139 // intra 16x16
140 #define I16DC16 (0 * 16 * BPS)
141 #define I16TM16 (1 * 16 * BPS)
142 #define I16VE16 (2 * 16 * BPS)
143 #define I16HE16 (3 * 16 * BPS)
144 // chroma 8x8, two U/V blocks side by side (hence: 16x8 each)
145 #define C8DC8 (4 * 16 * BPS)
146 #define C8TM8 (4 * 16 * BPS + 8 * BPS)
147 #define C8VE8 (5 * 16 * BPS)
148 #define C8HE8 (5 * 16 * BPS + 8 * BPS)
149 // intra 4x4
150 #define I4DC4 (6 * 16 * BPS +  0)
151 #define I4TM4 (6 * 16 * BPS +  4)
152 #define I4VE4 (6 * 16 * BPS +  8)
153 #define I4HE4 (6 * 16 * BPS + 12)
154 #define I4RD4 (6 * 16 * BPS + 4 * BPS +  0)
155 #define I4VR4 (6 * 16 * BPS + 4 * BPS +  4)
156 #define I4LD4 (6 * 16 * BPS + 4 * BPS +  8)
157 #define I4VL4 (6 * 16 * BPS + 4 * BPS + 12)
158 #define I4HD4 (6 * 16 * BPS + 8 * BPS +  0)
159 #define I4HU4 (6 * 16 * BPS + 8 * BPS +  4)
160 #define I4TMP (6 * 16 * BPS + 8 * BPS +  8)
161 
162 typedef int64_t score_t;     // type used for scores, rate, distortion
163 #define MAX_COST ((score_t)0x7fffffffffffffLL)
164 
165 #define QFIX 17
166 #define BIAS(b)  ((b) << (QFIX - 8))
167 // Fun fact: this is the _only_ line where we're actually being lossy and
168 // discarding bits.
QUANTDIV(int n,int iQ,int B)169 static WEBP_INLINE int QUANTDIV(int n, int iQ, int B) {
170   return (n * iQ + B) >> QFIX;
171 }
172 
173 // size of histogram used by CollectHistogram.
174 #define MAX_COEFF_THRESH   31
175 typedef struct VP8Histogram VP8Histogram;
176 struct VP8Histogram {
177   // TODO(skal): we only need to store the max_value and last_non_zero actually.
178   int distribution[MAX_COEFF_THRESH + 1];
179 };
180 
181 // Uncomment the following to remove token-buffer code:
182 // #define DISABLE_TOKEN_BUFFER
183 
184 //------------------------------------------------------------------------------
185 // Headers
186 
187 typedef uint32_t proba_t;   // 16b + 16b
188 typedef uint8_t ProbaArray[NUM_CTX][NUM_PROBAS];
189 typedef proba_t StatsArray[NUM_CTX][NUM_PROBAS];
190 typedef uint16_t CostArray[NUM_CTX][MAX_VARIABLE_LEVEL + 1];
191 typedef double LFStats[NUM_MB_SEGMENTS][MAX_LF_LEVELS];  // filter stats
192 
193 typedef struct VP8Encoder VP8Encoder;
194 
195 // segment features
196 typedef struct {
197   int num_segments_;      // Actual number of segments. 1 segment only = unused.
198   int update_map_;        // whether to update the segment map or not.
199                           // must be 0 if there's only 1 segment.
200   int size_;              // bit-cost for transmitting the segment map
201 } VP8SegmentHeader;
202 
203 // Struct collecting all frame-persistent probabilities.
204 typedef struct {
205   uint8_t segments_[3];     // probabilities for segment tree
206   uint8_t skip_proba_;      // final probability of being skipped.
207   ProbaArray coeffs_[NUM_TYPES][NUM_BANDS];      // 924 bytes
208   StatsArray stats_[NUM_TYPES][NUM_BANDS];       // 4224 bytes
209   CostArray level_cost_[NUM_TYPES][NUM_BANDS];   // 11.4k
210   int dirty_;               // if true, need to call VP8CalculateLevelCosts()
211   int use_skip_proba_;      // Note: we always use skip_proba for now.
212   int nb_skip_;             // number of skipped blocks
213 } VP8Proba;
214 
215 // Filter parameters. Not actually used in the code (we don't perform
216 // the in-loop filtering), but filled from user's config
217 typedef struct {
218   int simple_;             // filtering type: 0=complex, 1=simple
219   int level_;              // base filter level [0..63]
220   int sharpness_;          // [0..7]
221   int i4x4_lf_delta_;      // delta filter level for i4x4 relative to i16x16
222 } VP8FilterHeader;
223 
224 //------------------------------------------------------------------------------
225 // Informations about the macroblocks.
226 
227 typedef struct {
228   // block type
229   unsigned int type_:2;     // 0=i4x4, 1=i16x16
230   unsigned int uv_mode_:2;
231   unsigned int skip_:1;
232   unsigned int segment_:2;
233   uint8_t alpha_;      // quantization-susceptibility
234 } VP8MBInfo;
235 
236 typedef struct VP8Matrix {
237   uint16_t q_[16];        // quantizer steps
238   uint16_t iq_[16];       // reciprocals, fixed point.
239   uint16_t bias_[16];     // rounding bias
240   uint16_t zthresh_[16];  // value under which a coefficient is zeroed
241   uint16_t sharpen_[16];  // frequency boosters for slight sharpening
242 } VP8Matrix;
243 
244 typedef struct {
245   VP8Matrix y1_, y2_, uv_;  // quantization matrices
246   int alpha_;      // quant-susceptibility, range [-127,127]. Zero is neutral.
247                    // Lower values indicate a lower risk of blurriness.
248   int beta_;       // filter-susceptibility, range [0,255].
249   int quant_;      // final segment quantizer.
250   int fstrength_;  // final in-loop filtering strength
251   // reactivities
252   int lambda_i16_, lambda_i4_, lambda_uv_;
253   int lambda_mode_, lambda_trellis_, tlambda_;
254   int lambda_trellis_i16_, lambda_trellis_i4_, lambda_trellis_uv_;
255 } VP8SegmentInfo;
256 
257 // Handy transcient struct to accumulate score and info during RD-optimization
258 // and mode evaluation.
259 typedef struct {
260   score_t D, SD, R, score;    // Distortion, spectral distortion, rate, score.
261   int16_t y_dc_levels[16];    // Quantized levels for luma-DC, luma-AC, chroma.
262   int16_t y_ac_levels[16][16];
263   int16_t uv_levels[4 + 4][16];
264   int mode_i16;               // mode number for intra16 prediction
265   uint8_t modes_i4[16];       // mode numbers for intra4 predictions
266   int mode_uv;                // mode number of chroma prediction
267   uint32_t nz;                // non-zero blocks
268 } VP8ModeScore;
269 
270 // Iterator structure to iterate through macroblocks, pointing to the
271 // right neighbouring data (samples, predictions, contexts, ...)
272 typedef struct {
273   int x_, y_;                      // current macroblock
274   int y_offset_, uv_offset_;       // offset to the luma / chroma planes
275   int y_stride_, uv_stride_;       // respective strides
276   uint8_t*      yuv_in_;           // borrowed from enc_ (for now)
277   uint8_t*      yuv_out_;          // ''
278   uint8_t*      yuv_out2_;         // ''
279   uint8_t*      yuv_p_;            // ''
280   VP8Encoder*   enc_;              // back-pointer
281   VP8MBInfo*    mb_;               // current macroblock
282   VP8BitWriter* bw_;               // current bit-writer
283   uint8_t*      preds_;            // intra mode predictors (4x4 blocks)
284   uint32_t*     nz_;               // non-zero pattern
285   uint8_t       i4_boundary_[37];  // 32+5 boundary samples needed by intra4x4
286   uint8_t*      i4_top_;           // pointer to the current top boundary sample
287   int           i4_;               // current intra4x4 mode being tested
288   int           top_nz_[9];        // top-non-zero context.
289   int           left_nz_[9];       // left-non-zero. left_nz[8] is independent.
290   uint64_t      bit_count_[4][3];  // bit counters for coded levels.
291   uint64_t      luma_bits_;        // macroblock bit-cost for luma
292   uint64_t      uv_bits_;          // macroblock bit-cost for chroma
293   LFStats*      lf_stats_;         // filter stats (borrowed from enc_)
294   int           do_trellis_;       // if true, perform extra level optimisation
295   int           done_;             // true when scan is finished
296   int           percent0_;         // saved initial progress percent
297 } VP8EncIterator;
298 
299   // in iterator.c
300 // must be called first.
301 void VP8IteratorInit(VP8Encoder* const enc, VP8EncIterator* const it);
302 // restart a scan.
303 void VP8IteratorReset(VP8EncIterator* const it);
304 // import samples from source
305 void VP8IteratorImport(const VP8EncIterator* const it);
306 // export decimated samples
307 void VP8IteratorExport(const VP8EncIterator* const it);
308 // go to next macroblock. Returns !done_. If *block_to_save is non-null, will
309 // save the boundary values to top_/left_ arrays. block_to_save can be
310 // it->yuv_out_ or it->yuv_in_.
311 int VP8IteratorNext(VP8EncIterator* const it,
312                     const uint8_t* const block_to_save);
313 // Report progression based on macroblock rows. Return 0 for user-abort request.
314 int VP8IteratorProgress(const VP8EncIterator* const it,
315                         int final_delta_percent);
316 // Intra4x4 iterations
317 void VP8IteratorStartI4(VP8EncIterator* const it);
318 // returns true if not done.
319 int VP8IteratorRotateI4(VP8EncIterator* const it,
320                         const uint8_t* const yuv_out);
321 
322 // Non-zero context setup/teardown
323 void VP8IteratorNzToBytes(VP8EncIterator* const it);
324 void VP8IteratorBytesToNz(VP8EncIterator* const it);
325 
326 // Helper functions to set mode properties
327 void VP8SetIntra16Mode(const VP8EncIterator* const it, int mode);
328 void VP8SetIntra4Mode(const VP8EncIterator* const it, const uint8_t* modes);
329 void VP8SetIntraUVMode(const VP8EncIterator* const it, int mode);
330 void VP8SetSkip(const VP8EncIterator* const it, int skip);
331 void VP8SetSegment(const VP8EncIterator* const it, int segment);
332 
333 //------------------------------------------------------------------------------
334 // Paginated token buffer
335 
336 typedef struct VP8Tokens VP8Tokens;  // struct details in token.c
337 
338 typedef struct {
339 #if !defined(DISABLE_TOKEN_BUFFER)
340   VP8Tokens* pages_;        // first page
341   VP8Tokens** last_page_;   // last page
342   uint16_t* tokens_;        // set to (*last_page_)->tokens_
343   int left_;          // how many free tokens left before the page is full.
344 #endif
345   int error_;         // true in case of malloc error
346 } VP8TBuffer;
347 
348 void VP8TBufferInit(VP8TBuffer* const b);    // initialize an empty buffer
349 void VP8TBufferClear(VP8TBuffer* const b);   // de-allocate pages memory
350 
351 #if !defined(DISABLE_TOKEN_BUFFER)
352 
353 // Finalizes bitstream when probabilities are known.
354 // Deletes the allocated token memory if final_pass is true.
355 int VP8EmitTokens(VP8TBuffer* const b, VP8BitWriter* const bw,
356                   const uint8_t* const probas, int final_pass);
357 
358 // record the coding of coefficients without knowing the probabilities yet
359 int VP8RecordCoeffTokens(int ctx, int coeff_type, int first, int last,
360                          const int16_t* const coeffs,
361                          VP8TBuffer* const tokens);
362 
363 // unused for now
364 void VP8TokenToStats(const VP8TBuffer* const b, proba_t* const stats);
365 
366 #endif  // !DISABLE_TOKEN_BUFFER
367 
368 //------------------------------------------------------------------------------
369 // VP8Encoder
370 
371 struct VP8Encoder {
372   const WebPConfig* config_;    // user configuration and parameters
373   WebPPicture* pic_;            // input / output picture
374 
375   // headers
376   VP8FilterHeader   filter_hdr_;     // filtering information
377   VP8SegmentHeader  segment_hdr_;    // segment information
378 
379   int profile_;                      // VP8's profile, deduced from Config.
380 
381   // dimension, in macroblock units.
382   int mb_w_, mb_h_;
383   int preds_w_;   // stride of the *preds_ prediction plane (=4*mb_w + 1)
384 
385   // number of partitions (1, 2, 4 or 8 = MAX_NUM_PARTITIONS)
386   int num_parts_;
387 
388   // per-partition boolean decoders.
389   VP8BitWriter bw_;                         // part0
390   VP8BitWriter parts_[MAX_NUM_PARTITIONS];  // token partitions
391   VP8TBuffer tokens_;                       // token buffer
392 
393   int percent_;                             // for progress
394 
395   // transparency blob
396   int has_alpha_;
397   uint8_t* alpha_data_;       // non-NULL if transparency is present
398   uint32_t alpha_data_size_;
399   WebPWorker alpha_worker_;
400 
401   // enhancement layer
402   int use_layer_;
403   VP8BitWriter layer_bw_;
404   uint8_t* layer_data_;
405   size_t layer_data_size_;
406 
407   // quantization info (one set of DC/AC dequant factor per segment)
408   VP8SegmentInfo dqm_[NUM_MB_SEGMENTS];
409   int base_quant_;                 // nominal quantizer value. Only used
410                                    // for relative coding of segments' quant.
411   int alpha_;                      // global susceptibility (<=> complexity)
412   int uv_alpha_;                   // U/V quantization susceptibility
413   // global offset of quantizers, shared by all segments
414   int dq_y1_dc_;
415   int dq_y2_dc_, dq_y2_ac_;
416   int dq_uv_dc_, dq_uv_ac_;
417 
418   // probabilities and statistics
419   VP8Proba proba_;
420   uint64_t sse_[4];        // sum of Y/U/V/A squared errors for all macroblocks
421   uint64_t sse_count_;     // pixel count for the sse_[] stats
422   int      coded_size_;
423   int      residual_bytes_[3][4];
424   int      block_count_[3];
425 
426   // quality/speed settings
427   int method_;               // 0=fastest, 6=best/slowest.
428   VP8RDLevel rd_opt_level_;  // Deduced from method_.
429   int max_i4_header_bits_;   // partition #0 safeness factor
430   int thread_level_;         // derived from config->thread_level
431   int do_search_;            // derived from config->target_XXX
432   int use_tokens_;           // if true, use token buffer
433 
434   // Memory
435   VP8MBInfo* mb_info_;   // contextual macroblock infos (mb_w_ + 1)
436   uint8_t*   preds_;     // predictions modes: (4*mb_w+1) * (4*mb_h+1)
437   uint32_t*  nz_;        // non-zero bit context: mb_w+1
438   uint8_t*   yuv_in_;    // input samples
439   uint8_t*   yuv_out_;   // output samples
440   uint8_t*   yuv_out2_;  // secondary scratch out-buffer. swapped with yuv_out_.
441   uint8_t*   yuv_p_;     // scratch buffer for prediction
442   uint8_t   *y_top_;     // top luma samples.
443   uint8_t   *uv_top_;    // top u/v samples.
444                          // U and V are packed into 16 pixels (8 U + 8 V)
445   uint8_t   *y_left_;    // left luma samples (adressable from index -1 to 15).
446   uint8_t   *u_left_;    // left u samples (adressable from index -1 to 7)
447   uint8_t   *v_left_;    // left v samples (adressable from index -1 to 7)
448 
449   LFStats   *lf_stats_;  // autofilter stats (if NULL, autofilter is off)
450 };
451 
452 //------------------------------------------------------------------------------
453 // internal functions. Not public.
454 
455   // in tree.c
456 extern const uint8_t VP8CoeffsProba0[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS];
457 extern const uint8_t
458     VP8CoeffsUpdateProba[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS];
459 // Reset the token probabilities to their initial (default) values
460 void VP8DefaultProbas(VP8Encoder* const enc);
461 // Write the token probabilities
462 void VP8WriteProbas(VP8BitWriter* const bw, const VP8Proba* const probas);
463 // Writes the partition #0 modes (that is: all intra modes)
464 void VP8CodeIntraModes(VP8Encoder* const enc);
465 
466   // in syntax.c
467 // Generates the final bitstream by coding the partition0 and headers,
468 // and appending an assembly of all the pre-coded token partitions.
469 // Return true if everything is ok.
470 int VP8EncWrite(VP8Encoder* const enc);
471 // Release memory allocated for bit-writing in VP8EncLoop & seq.
472 void VP8EncFreeBitWriters(VP8Encoder* const enc);
473 
474   // in frame.c
475 extern const uint8_t VP8EncBands[16 + 1];
476 extern const uint8_t VP8Cat3[];
477 extern const uint8_t VP8Cat4[];
478 extern const uint8_t VP8Cat5[];
479 extern const uint8_t VP8Cat6[];
480 
481 // Form all the four Intra16x16 predictions in the yuv_p_ cache
482 void VP8MakeLuma16Preds(const VP8EncIterator* const it);
483 // Form all the four Chroma8x8 predictions in the yuv_p_ cache
484 void VP8MakeChroma8Preds(const VP8EncIterator* const it);
485 // Form all the ten Intra4x4 predictions in the yuv_p_ cache
486 // for the 4x4 block it->i4_
487 void VP8MakeIntra4Preds(const VP8EncIterator* const it);
488 // Rate calculation
489 int VP8GetCostLuma16(VP8EncIterator* const it, const VP8ModeScore* const rd);
490 int VP8GetCostLuma4(VP8EncIterator* const it, const int16_t levels[16]);
491 int VP8GetCostUV(VP8EncIterator* const it, const VP8ModeScore* const rd);
492 // Main coding calls
493 int VP8EncLoop(VP8Encoder* const enc);
494 int VP8EncTokenLoop(VP8Encoder* const enc);
495 
496   // in webpenc.c
497 // Assign an error code to a picture. Return false for convenience.
498 int WebPEncodingSetError(const WebPPicture* const pic, WebPEncodingError error);
499 int WebPReportProgress(const WebPPicture* const pic,
500                        int percent, int* const percent_store);
501 
502   // in analysis.c
503 // Main analysis loop. Decides the segmentations and complexity.
504 // Assigns a first guess for Intra16 and uvmode_ prediction modes.
505 int VP8EncAnalyze(VP8Encoder* const enc);
506 
507   // in quant.c
508 // Sets up segment's quantization values, base_quant_ and filter strengths.
509 void VP8SetSegmentParams(VP8Encoder* const enc, float quality);
510 // Pick best modes and fills the levels. Returns true if skipped.
511 int VP8Decimate(VP8EncIterator* const it, VP8ModeScore* const rd,
512                 VP8RDLevel rd_opt);
513 
514   // in alpha.c
515 void VP8EncInitAlpha(VP8Encoder* const enc);    // initialize alpha compression
516 int VP8EncStartAlpha(VP8Encoder* const enc);    // start alpha coding process
517 int VP8EncFinishAlpha(VP8Encoder* const enc);   // finalize compressed data
518 int VP8EncDeleteAlpha(VP8Encoder* const enc);   // delete compressed data
519 
520   // in layer.c
521 void VP8EncInitLayer(VP8Encoder* const enc);     // init everything
522 void VP8EncCodeLayerBlock(VP8EncIterator* it);   // code one more macroblock
523 int VP8EncFinishLayer(VP8Encoder* const enc);    // finalize coding
524 void VP8EncDeleteLayer(VP8Encoder* enc);         // reclaim memory
525 
526   // in filter.c
527 
528 // SSIM utils
529 typedef struct {
530   double w, xm, ym, xxm, xym, yym;
531 } DistoStats;
532 void VP8SSIMAddStats(const DistoStats* const src, DistoStats* const dst);
533 void VP8SSIMAccumulatePlane(const uint8_t* src1, int stride1,
534                             const uint8_t* src2, int stride2,
535                             int W, int H, DistoStats* const stats);
536 double VP8SSIMGet(const DistoStats* const stats);
537 double VP8SSIMGetSquaredError(const DistoStats* const stats);
538 
539 // autofilter
540 void VP8InitFilter(VP8EncIterator* const it);
541 void VP8StoreFilterStats(VP8EncIterator* const it);
542 void VP8AdjustFilterStrength(VP8EncIterator* const it);
543 
544 //------------------------------------------------------------------------------
545 
546 #if defined(__cplusplus) || defined(c_plusplus)
547 }    // extern "C"
548 #endif
549 
550 #endif  /* WEBP_ENC_VP8ENCI_H_ */
551