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      1 // Copyright 2011 Google Inc. All Rights Reserved.
      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 //   WebP encoder: internal header.
      9 //
     10 // Author: Skal (pascal.massimino (at) gmail.com)
     11 
     12 #ifndef WEBP_ENC_VP8ENCI_H_
     13 #define WEBP_ENC_VP8ENCI_H_
     14 
     15 #include <string.h>     // for memcpy()
     16 #include "webp/encode.h"
     17 #include "../dsp/dsp.h"
     18 #include "../utils/bit_writer.h"
     19 #include "../utils/thread.h"
     20 
     21 #if defined(__cplusplus) || defined(c_plusplus)
     22 extern "C" {
     23 #endif
     24 
     25 //------------------------------------------------------------------------------
     26 // Various defines and enums
     27 
     28 // version numbers
     29 #define ENC_MAJ_VERSION 0
     30 #define ENC_MIN_VERSION 2
     31 #define ENC_REV_VERSION 1
     32 
     33 // intra prediction modes
     34 enum { B_DC_PRED = 0,   // 4x4 modes
     35        B_TM_PRED = 1,
     36        B_VE_PRED = 2,
     37        B_HE_PRED = 3,
     38        B_RD_PRED = 4,
     39        B_VR_PRED = 5,
     40        B_LD_PRED = 6,
     41        B_VL_PRED = 7,
     42        B_HD_PRED = 8,
     43        B_HU_PRED = 9,
     44        NUM_BMODES = B_HU_PRED + 1 - B_DC_PRED,  // = 10
     45 
     46        // Luma16 or UV modes
     47        DC_PRED = B_DC_PRED, V_PRED = B_VE_PRED,
     48        H_PRED = B_HE_PRED, TM_PRED = B_TM_PRED,
     49        NUM_PRED_MODES = 4
     50      };
     51 
     52 enum { NUM_MB_SEGMENTS = 4,
     53        MAX_NUM_PARTITIONS = 8,
     54        NUM_TYPES = 4,   // 0: i16-AC,  1: i16-DC,  2:chroma-AC,  3:i4-AC
     55        NUM_BANDS = 8,
     56        NUM_CTX = 3,
     57        NUM_PROBAS = 11,
     58        MAX_LF_LEVELS = 64,      // Maximum loop filter level
     59        MAX_VARIABLE_LEVEL = 67  // last (inclusive) level with variable cost
     60      };
     61 
     62 typedef enum {   // Rate-distortion optimization levels
     63   RD_OPT_NONE        = 0,  // no rd-opt
     64   RD_OPT_BASIC       = 1,  // basic scoring (no trellis)
     65   RD_OPT_TRELLIS     = 2,  // perform trellis-quant on the final decision only
     66   RD_OPT_TRELLIS_ALL = 3   // trellis-quant for every scoring (much slower)
     67 } VP8RDLevel;
     68 
     69 // YUV-cache parameters. Cache is 16-pixels wide.
     70 // The original or reconstructed samples can be accessed using VP8Scan[]
     71 // The predicted blocks can be accessed using offsets to yuv_p_ and
     72 // the arrays VP8*ModeOffsets[];
     73 //         +----+      YUV Samples area. See VP8Scan[] for accessing the blocks.
     74 //  Y_OFF  |YYYY| <- original samples  (enc->yuv_in_)
     75 //         |YYYY|
     76 //         |YYYY|
     77 //         |YYYY|
     78 //  U_OFF  |UUVV| V_OFF  (=U_OFF + 8)
     79 //         |UUVV|
     80 //         +----+
     81 //  Y_OFF  |YYYY| <- compressed/decoded samples  ('yuv_out_')
     82 //         |YYYY|    There are two buffers like this ('yuv_out_'/'yuv_out2_')
     83 //         |YYYY|
     84 //         |YYYY|
     85 //  U_OFF  |UUVV| V_OFF
     86 //         |UUVV|
     87 //          x2 (for yuv_out2_)
     88 //         +----+     Prediction area ('yuv_p_', size = PRED_SIZE)
     89 // I16DC16 |YYYY|  Intra16 predictions (16x16 block each)
     90 //         |YYYY|
     91 //         |YYYY|
     92 //         |YYYY|
     93 // I16TM16 |YYYY|
     94 //         |YYYY|
     95 //         |YYYY|
     96 //         |YYYY|
     97 // I16VE16 |YYYY|
     98 //         |YYYY|
     99 //         |YYYY|
    100 //         |YYYY|
    101 // I16HE16 |YYYY|
    102 //         |YYYY|
    103 //         |YYYY|
    104 //         |YYYY|
    105 //         +----+  Chroma U/V predictions (16x8 block each)
    106 // C8DC8   |UUVV|
    107 //         |UUVV|
    108 // C8TM8   |UUVV|
    109 //         |UUVV|
    110 // C8VE8   |UUVV|
    111 //         |UUVV|
    112 // C8HE8   |UUVV|
    113 //         |UUVV|
    114 //         +----+  Intra 4x4 predictions (4x4 block each)
    115 //         |YYYY| I4DC4 I4TM4 I4VE4 I4HE4
    116 //         |YYYY| I4RD4 I4VR4 I4LD4 I4VL4
    117 //         |YY..| I4HD4 I4HU4 I4TMP
    118 //         +----+
    119 #define BPS       16   // this is the common stride
    120 #define Y_SIZE   (BPS * 16)
    121 #define UV_SIZE  (BPS * 8)
    122 #define YUV_SIZE (Y_SIZE + UV_SIZE)
    123 #define PRED_SIZE (6 * 16 * BPS + 12 * BPS)
    124 #define Y_OFF    (0)
    125 #define U_OFF    (Y_SIZE)
    126 #define V_OFF    (U_OFF + 8)
    127 #define ALIGN_CST 15
    128 #define DO_ALIGN(PTR) ((uintptr_t)((PTR) + ALIGN_CST) & ~ALIGN_CST)
    129 
    130 extern const int VP8Scan[16 + 4 + 4];           // in quant.c
    131 extern const int VP8UVModeOffsets[4];           // in analyze.c
    132 extern const int VP8I16ModeOffsets[4];
    133 extern const int VP8I4ModeOffsets[NUM_BMODES];
    134 
    135 // Layout of prediction blocks
    136 // intra 16x16
    137 #define I16DC16 (0 * 16 * BPS)
    138 #define I16TM16 (1 * 16 * BPS)
    139 #define I16VE16 (2 * 16 * BPS)
    140 #define I16HE16 (3 * 16 * BPS)
    141 // chroma 8x8, two U/V blocks side by side (hence: 16x8 each)
    142 #define C8DC8 (4 * 16 * BPS)
    143 #define C8TM8 (4 * 16 * BPS + 8 * BPS)
    144 #define C8VE8 (5 * 16 * BPS)
    145 #define C8HE8 (5 * 16 * BPS + 8 * BPS)
    146 // intra 4x4
    147 #define I4DC4 (6 * 16 * BPS +  0)
    148 #define I4TM4 (6 * 16 * BPS +  4)
    149 #define I4VE4 (6 * 16 * BPS +  8)
    150 #define I4HE4 (6 * 16 * BPS + 12)
    151 #define I4RD4 (6 * 16 * BPS + 4 * BPS +  0)
    152 #define I4VR4 (6 * 16 * BPS + 4 * BPS +  4)
    153 #define I4LD4 (6 * 16 * BPS + 4 * BPS +  8)
    154 #define I4VL4 (6 * 16 * BPS + 4 * BPS + 12)
    155 #define I4HD4 (6 * 16 * BPS + 8 * BPS +  0)
    156 #define I4HU4 (6 * 16 * BPS + 8 * BPS +  4)
    157 #define I4TMP (6 * 16 * BPS + 8 * BPS +  8)
    158 
    159 typedef int64_t score_t;     // type used for scores, rate, distortion
    160 #define MAX_COST ((score_t)0x7fffffffffffffLL)
    161 
    162 #define QFIX 17
    163 #define BIAS(b)  ((b) << (QFIX - 8))
    164 // Fun fact: this is the _only_ line where we're actually being lossy and
    165 // discarding bits.
    166 static WEBP_INLINE int QUANTDIV(int n, int iQ, int B) {
    167   return (n * iQ + B) >> QFIX;
    168 }
    169 
    170 // size of histogram used by CollectHistogram.
    171 #define MAX_COEFF_THRESH   31
    172 typedef struct VP8Histogram VP8Histogram;
    173 struct VP8Histogram {
    174   // TODO(skal): we only need to store the max_value and last_non_zero actually.
    175   int distribution[MAX_COEFF_THRESH + 1];
    176 };
    177 
    178 // Uncomment the following to remove token-buffer code:
    179 // #define DISABLE_TOKEN_BUFFER
    180 
    181 //------------------------------------------------------------------------------
    182 // Headers
    183 
    184 typedef uint32_t proba_t;   // 16b + 16b
    185 typedef uint8_t ProbaArray[NUM_CTX][NUM_PROBAS];
    186 typedef proba_t StatsArray[NUM_CTX][NUM_PROBAS];
    187 typedef uint16_t CostArray[NUM_CTX][MAX_VARIABLE_LEVEL + 1];
    188 typedef double LFStats[NUM_MB_SEGMENTS][MAX_LF_LEVELS];  // filter stats
    189 
    190 typedef struct VP8Encoder VP8Encoder;
    191 
    192 // segment features
    193 typedef struct {
    194   int num_segments_;      // Actual number of segments. 1 segment only = unused.
    195   int update_map_;        // whether to update the segment map or not.
    196                           // must be 0 if there's only 1 segment.
    197   int size_;              // bit-cost for transmitting the segment map
    198 } VP8SegmentHeader;
    199 
    200 // Struct collecting all frame-persistent probabilities.
    201 typedef struct {
    202   uint8_t segments_[3];     // probabilities for segment tree
    203   uint8_t skip_proba_;      // final probability of being skipped.
    204   ProbaArray coeffs_[NUM_TYPES][NUM_BANDS];      // 924 bytes
    205   StatsArray stats_[NUM_TYPES][NUM_BANDS];       // 4224 bytes
    206   CostArray level_cost_[NUM_TYPES][NUM_BANDS];   // 11.4k
    207   int dirty_;               // if true, need to call VP8CalculateLevelCosts()
    208   int use_skip_proba_;      // Note: we always use skip_proba for now.
    209   int nb_skip_;             // number of skipped blocks
    210 } VP8Proba;
    211 
    212 // Filter parameters. Not actually used in the code (we don't perform
    213 // the in-loop filtering), but filled from user's config
    214 typedef struct {
    215   int simple_;             // filtering type: 0=complex, 1=simple
    216   int level_;              // base filter level [0..63]
    217   int sharpness_;          // [0..7]
    218   int i4x4_lf_delta_;      // delta filter level for i4x4 relative to i16x16
    219 } VP8FilterHeader;
    220 
    221 //------------------------------------------------------------------------------
    222 // Informations about the macroblocks.
    223 
    224 typedef struct {
    225   // block type
    226   unsigned int type_:2;     // 0=i4x4, 1=i16x16
    227   unsigned int uv_mode_:2;
    228   unsigned int skip_:1;
    229   unsigned int segment_:2;
    230   uint8_t alpha_;      // quantization-susceptibility
    231 } VP8MBInfo;
    232 
    233 typedef struct VP8Matrix {
    234   uint16_t q_[16];        // quantizer steps
    235   uint16_t iq_[16];       // reciprocals, fixed point.
    236   uint16_t bias_[16];     // rounding bias
    237   uint16_t zthresh_[16];  // value under which a coefficient is zeroed
    238   uint16_t sharpen_[16];  // frequency boosters for slight sharpening
    239 } VP8Matrix;
    240 
    241 typedef struct {
    242   VP8Matrix y1_, y2_, uv_;  // quantization matrices
    243   int alpha_;      // quant-susceptibility, range [-127,127]. Zero is neutral.
    244                    // Lower values indicate a lower risk of blurriness.
    245   int beta_;       // filter-susceptibility, range [0,255].
    246   int quant_;      // final segment quantizer.
    247   int fstrength_;  // final in-loop filtering strength
    248   // reactivities
    249   int lambda_i16_, lambda_i4_, lambda_uv_;
    250   int lambda_mode_, lambda_trellis_, tlambda_;
    251   int lambda_trellis_i16_, lambda_trellis_i4_, lambda_trellis_uv_;
    252 } VP8SegmentInfo;
    253 
    254 // Handy transcient struct to accumulate score and info during RD-optimization
    255 // and mode evaluation.
    256 typedef struct {
    257   score_t D, SD, R, score;    // Distortion, spectral distortion, rate, score.
    258   int16_t y_dc_levels[16];    // Quantized levels for luma-DC, luma-AC, chroma.
    259   int16_t y_ac_levels[16][16];
    260   int16_t uv_levels[4 + 4][16];
    261   int mode_i16;               // mode number for intra16 prediction
    262   uint8_t modes_i4[16];       // mode numbers for intra4 predictions
    263   int mode_uv;                // mode number of chroma prediction
    264   uint32_t nz;                // non-zero blocks
    265 } VP8ModeScore;
    266 
    267 // Iterator structure to iterate through macroblocks, pointing to the
    268 // right neighbouring data (samples, predictions, contexts, ...)
    269 typedef struct {
    270   int x_, y_;                      // current macroblock
    271   int y_offset_, uv_offset_;       // offset to the luma / chroma planes
    272   int y_stride_, uv_stride_;       // respective strides
    273   uint8_t*      yuv_in_;           // borrowed from enc_ (for now)
    274   uint8_t*      yuv_out_;          // ''
    275   uint8_t*      yuv_out2_;         // ''
    276   uint8_t*      yuv_p_;            // ''
    277   VP8Encoder*   enc_;              // back-pointer
    278   VP8MBInfo*    mb_;               // current macroblock
    279   VP8BitWriter* bw_;               // current bit-writer
    280   uint8_t*      preds_;            // intra mode predictors (4x4 blocks)
    281   uint32_t*     nz_;               // non-zero pattern
    282   uint8_t       i4_boundary_[37];  // 32+5 boundary samples needed by intra4x4
    283   uint8_t*      i4_top_;           // pointer to the current top boundary sample
    284   int           i4_;               // current intra4x4 mode being tested
    285   int           top_nz_[9];        // top-non-zero context.
    286   int           left_nz_[9];       // left-non-zero. left_nz[8] is independent.
    287   uint64_t      bit_count_[4][3];  // bit counters for coded levels.
    288   uint64_t      luma_bits_;        // macroblock bit-cost for luma
    289   uint64_t      uv_bits_;          // macroblock bit-cost for chroma
    290   LFStats*      lf_stats_;         // filter stats (borrowed from enc_)
    291   int           do_trellis_;       // if true, perform extra level optimisation
    292   int           done_;             // true when scan is finished
    293   int           percent0_;         // saved initial progress percent
    294 } VP8EncIterator;
    295 
    296   // in iterator.c
    297 // must be called first.
    298 void VP8IteratorInit(VP8Encoder* const enc, VP8EncIterator* const it);
    299 // restart a scan.
    300 void VP8IteratorReset(VP8EncIterator* const it);
    301 // import samples from source
    302 void VP8IteratorImport(const VP8EncIterator* const it);
    303 // export decimated samples
    304 void VP8IteratorExport(const VP8EncIterator* const it);
    305 // go to next macroblock. Returns !done_. If *block_to_save is non-null, will
    306 // save the boundary values to top_/left_ arrays. block_to_save can be
    307 // it->yuv_out_ or it->yuv_in_.
    308 int VP8IteratorNext(VP8EncIterator* const it,
    309                     const uint8_t* const block_to_save);
    310 // Report progression based on macroblock rows. Return 0 for user-abort request.
    311 int VP8IteratorProgress(const VP8EncIterator* const it,
    312                         int final_delta_percent);
    313 // Intra4x4 iterations
    314 void VP8IteratorStartI4(VP8EncIterator* const it);
    315 // returns true if not done.
    316 int VP8IteratorRotateI4(VP8EncIterator* const it,
    317                         const uint8_t* const yuv_out);
    318 
    319 // Non-zero context setup/teardown
    320 void VP8IteratorNzToBytes(VP8EncIterator* const it);
    321 void VP8IteratorBytesToNz(VP8EncIterator* const it);
    322 
    323 // Helper functions to set mode properties
    324 void VP8SetIntra16Mode(const VP8EncIterator* const it, int mode);
    325 void VP8SetIntra4Mode(const VP8EncIterator* const it, const uint8_t* modes);
    326 void VP8SetIntraUVMode(const VP8EncIterator* const it, int mode);
    327 void VP8SetSkip(const VP8EncIterator* const it, int skip);
    328 void VP8SetSegment(const VP8EncIterator* const it, int segment);
    329 
    330 //------------------------------------------------------------------------------
    331 // Paginated token buffer
    332 
    333 typedef struct VP8Tokens VP8Tokens;  // struct details in token.c
    334 
    335 typedef struct {
    336 #if !defined(DISABLE_TOKEN_BUFFER)
    337   VP8Tokens* pages_;        // first page
    338   VP8Tokens** last_page_;   // last page
    339   uint16_t* tokens_;        // set to (*last_page_)->tokens_
    340   int left_;          // how many free tokens left before the page is full.
    341 #endif
    342   int error_;         // true in case of malloc error
    343 } VP8TBuffer;
    344 
    345 void VP8TBufferInit(VP8TBuffer* const b);    // initialize an empty buffer
    346 void VP8TBufferClear(VP8TBuffer* const b);   // de-allocate pages memory
    347 
    348 #if !defined(DISABLE_TOKEN_BUFFER)
    349 
    350 // Finalizes bitstream when probabilities are known.
    351 // Deletes the allocated token memory if final_pass is true.
    352 int VP8EmitTokens(VP8TBuffer* const b, VP8BitWriter* const bw,
    353                   const uint8_t* const probas, int final_pass);
    354 
    355 // record the coding of coefficients without knowing the probabilities yet
    356 int VP8RecordCoeffTokens(int ctx, int coeff_type, int first, int last,
    357                          const int16_t* const coeffs,
    358                          VP8TBuffer* const tokens);
    359 
    360 // unused for now
    361 void VP8TokenToStats(const VP8TBuffer* const b, proba_t* const stats);
    362 
    363 #endif  // !DISABLE_TOKEN_BUFFER
    364 
    365 //------------------------------------------------------------------------------
    366 // VP8Encoder
    367 
    368 struct VP8Encoder {
    369   const WebPConfig* config_;    // user configuration and parameters
    370   WebPPicture* pic_;            // input / output picture
    371 
    372   // headers
    373   VP8FilterHeader   filter_hdr_;     // filtering information
    374   VP8SegmentHeader  segment_hdr_;    // segment information
    375 
    376   int profile_;                      // VP8's profile, deduced from Config.
    377 
    378   // dimension, in macroblock units.
    379   int mb_w_, mb_h_;
    380   int preds_w_;   // stride of the *preds_ prediction plane (=4*mb_w + 1)
    381 
    382   // number of partitions (1, 2, 4 or 8 = MAX_NUM_PARTITIONS)
    383   int num_parts_;
    384 
    385   // per-partition boolean decoders.
    386   VP8BitWriter bw_;                         // part0
    387   VP8BitWriter parts_[MAX_NUM_PARTITIONS];  // token partitions
    388   VP8TBuffer tokens_;                       // token buffer
    389 
    390   int percent_;                             // for progress
    391 
    392   // transparency blob
    393   int has_alpha_;
    394   uint8_t* alpha_data_;       // non-NULL if transparency is present
    395   uint32_t alpha_data_size_;
    396   WebPWorker alpha_worker_;
    397 
    398   // enhancement layer
    399   int use_layer_;
    400   VP8BitWriter layer_bw_;
    401   uint8_t* layer_data_;
    402   size_t layer_data_size_;
    403 
    404   // quantization info (one set of DC/AC dequant factor per segment)
    405   VP8SegmentInfo dqm_[NUM_MB_SEGMENTS];
    406   int base_quant_;                 // nominal quantizer value. Only used
    407                                    // for relative coding of segments' quant.
    408   int alpha_;                      // global susceptibility (<=> complexity)
    409   int uv_alpha_;                   // U/V quantization susceptibility
    410   // global offset of quantizers, shared by all segments
    411   int dq_y1_dc_;
    412   int dq_y2_dc_, dq_y2_ac_;
    413   int dq_uv_dc_, dq_uv_ac_;
    414 
    415   // probabilities and statistics
    416   VP8Proba proba_;
    417   uint64_t sse_[4];        // sum of Y/U/V/A squared errors for all macroblocks
    418   uint64_t sse_count_;     // pixel count for the sse_[] stats
    419   int      coded_size_;
    420   int      residual_bytes_[3][4];
    421   int      block_count_[3];
    422 
    423   // quality/speed settings
    424   int method_;               // 0=fastest, 6=best/slowest.
    425   VP8RDLevel rd_opt_level_;  // Deduced from method_.
    426   int max_i4_header_bits_;   // partition #0 safeness factor
    427   int thread_level_;         // derived from config->thread_level
    428   int do_search_;            // derived from config->target_XXX
    429   int use_tokens_;           // if true, use token buffer
    430 
    431   // Memory
    432   VP8MBInfo* mb_info_;   // contextual macroblock infos (mb_w_ + 1)
    433   uint8_t*   preds_;     // predictions modes: (4*mb_w+1) * (4*mb_h+1)
    434   uint32_t*  nz_;        // non-zero bit context: mb_w+1
    435   uint8_t*   yuv_in_;    // input samples
    436   uint8_t*   yuv_out_;   // output samples
    437   uint8_t*   yuv_out2_;  // secondary scratch out-buffer. swapped with yuv_out_.
    438   uint8_t*   yuv_p_;     // scratch buffer for prediction
    439   uint8_t   *y_top_;     // top luma samples.
    440   uint8_t   *uv_top_;    // top u/v samples.
    441                          // U and V are packed into 16 pixels (8 U + 8 V)
    442   uint8_t   *y_left_;    // left luma samples (adressable from index -1 to 15).
    443   uint8_t   *u_left_;    // left u samples (adressable from index -1 to 7)
    444   uint8_t   *v_left_;    // left v samples (adressable from index -1 to 7)
    445 
    446   LFStats   *lf_stats_;  // autofilter stats (if NULL, autofilter is off)
    447 };
    448 
    449 //------------------------------------------------------------------------------
    450 // internal functions. Not public.
    451 
    452   // in tree.c
    453 extern const uint8_t VP8CoeffsProba0[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS];
    454 extern const uint8_t
    455     VP8CoeffsUpdateProba[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS];
    456 // Reset the token probabilities to their initial (default) values
    457 void VP8DefaultProbas(VP8Encoder* const enc);
    458 // Write the token probabilities
    459 void VP8WriteProbas(VP8BitWriter* const bw, const VP8Proba* const probas);
    460 // Writes the partition #0 modes (that is: all intra modes)
    461 void VP8CodeIntraModes(VP8Encoder* const enc);
    462 
    463   // in syntax.c
    464 // Generates the final bitstream by coding the partition0 and headers,
    465 // and appending an assembly of all the pre-coded token partitions.
    466 // Return true if everything is ok.
    467 int VP8EncWrite(VP8Encoder* const enc);
    468 // Release memory allocated for bit-writing in VP8EncLoop & seq.
    469 void VP8EncFreeBitWriters(VP8Encoder* const enc);
    470 
    471   // in frame.c
    472 extern const uint8_t VP8EncBands[16 + 1];
    473 extern const uint8_t VP8Cat3[];
    474 extern const uint8_t VP8Cat4[];
    475 extern const uint8_t VP8Cat5[];
    476 extern const uint8_t VP8Cat6[];
    477 
    478 // Form all the four Intra16x16 predictions in the yuv_p_ cache
    479 void VP8MakeLuma16Preds(const VP8EncIterator* const it);
    480 // Form all the four Chroma8x8 predictions in the yuv_p_ cache
    481 void VP8MakeChroma8Preds(const VP8EncIterator* const it);
    482 // Form all the ten Intra4x4 predictions in the yuv_p_ cache
    483 // for the 4x4 block it->i4_
    484 void VP8MakeIntra4Preds(const VP8EncIterator* const it);
    485 // Rate calculation
    486 int VP8GetCostLuma16(VP8EncIterator* const it, const VP8ModeScore* const rd);
    487 int VP8GetCostLuma4(VP8EncIterator* const it, const int16_t levels[16]);
    488 int VP8GetCostUV(VP8EncIterator* const it, const VP8ModeScore* const rd);
    489 // Main coding calls
    490 int VP8EncLoop(VP8Encoder* const enc);
    491 int VP8EncTokenLoop(VP8Encoder* const enc);
    492 
    493   // in webpenc.c
    494 // Assign an error code to a picture. Return false for convenience.
    495 int WebPEncodingSetError(const WebPPicture* const pic, WebPEncodingError error);
    496 int WebPReportProgress(const WebPPicture* const pic,
    497                        int percent, int* const percent_store);
    498 
    499   // in analysis.c
    500 // Main analysis loop. Decides the segmentations and complexity.
    501 // Assigns a first guess for Intra16 and uvmode_ prediction modes.
    502 int VP8EncAnalyze(VP8Encoder* const enc);
    503 
    504   // in quant.c
    505 // Sets up segment's quantization values, base_quant_ and filter strengths.
    506 void VP8SetSegmentParams(VP8Encoder* const enc, float quality);
    507 // Pick best modes and fills the levels. Returns true if skipped.
    508 int VP8Decimate(VP8EncIterator* const it, VP8ModeScore* const rd,
    509                 VP8RDLevel rd_opt);
    510 
    511   // in alpha.c
    512 void VP8EncInitAlpha(VP8Encoder* const enc);    // initialize alpha compression
    513 int VP8EncStartAlpha(VP8Encoder* const enc);    // start alpha coding process
    514 int VP8EncFinishAlpha(VP8Encoder* const enc);   // finalize compressed data
    515 int VP8EncDeleteAlpha(VP8Encoder* const enc);   // delete compressed data
    516 
    517   // in layer.c
    518 void VP8EncInitLayer(VP8Encoder* const enc);     // init everything
    519 void VP8EncCodeLayerBlock(VP8EncIterator* it);   // code one more macroblock
    520 int VP8EncFinishLayer(VP8Encoder* const enc);    // finalize coding
    521 void VP8EncDeleteLayer(VP8Encoder* enc);         // reclaim memory
    522 
    523   // in filter.c
    524 
    525 // SSIM utils
    526 typedef struct {
    527   double w, xm, ym, xxm, xym, yym;
    528 } DistoStats;
    529 void VP8SSIMAddStats(const DistoStats* const src, DistoStats* const dst);
    530 void VP8SSIMAccumulatePlane(const uint8_t* src1, int stride1,
    531                             const uint8_t* src2, int stride2,
    532                             int W, int H, DistoStats* const stats);
    533 double VP8SSIMGet(const DistoStats* const stats);
    534 double VP8SSIMGetSquaredError(const DistoStats* const stats);
    535 
    536 // autofilter
    537 void VP8InitFilter(VP8EncIterator* const it);
    538 void VP8StoreFilterStats(VP8EncIterator* const it);
    539 void VP8AdjustFilterStrength(VP8EncIterator* const it);
    540 
    541 //------------------------------------------------------------------------------
    542 
    543 #if defined(__cplusplus) || defined(c_plusplus)
    544 }    // extern "C"
    545 #endif
    546 
    547 #endif  /* WEBP_ENC_VP8ENCI_H_ */
    548