third_party/libwebp/dec/vp8i.h

   1 // Copyright 2010 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 // VP8 decoder: internal header.
  11 //
  12 // Author: Skal (pascal.massimino@gmail.com)
  13
  14 #ifndef WEBP_DEC_VP8I_H_
  15 #define WEBP_DEC_VP8I_H_
  16
  17 #include <string.h>     // for memcpy()
  18 #include "./vp8li.h"
  19 #include "../utils/bit_reader.h"
  20 #include "../utils/random.h"
  21 #include "../utils/thread.h"
  22 #include "../dsp/dsp.h"
  23
  24 #ifdef __cplusplus
  25 extern "C" {
  26 #endif
  27
  28 //------------------------------------------------------------------------------
  29 // Various defines and enums
  30
  31 // version numbers
  32 #define DEC_MAJ_VERSION 0
  33 #define DEC_MIN_VERSION 4
  34 #define DEC_REV_VERSION 3
  35
  36 // intra prediction modes
  37 enum { B_DC_PRED = 0,   // 4x4 modes
  38        B_TM_PRED,
  39        B_VE_PRED,
  40        B_HE_PRED,
  41        B_RD_PRED,
  42        B_VR_PRED,
  43        B_LD_PRED,
  44        B_VL_PRED,
  45        B_HD_PRED,
  46        B_HU_PRED,
  47        NUM_BMODES = B_HU_PRED + 1 - B_DC_PRED,  // = 10
  48
  49        // Luma16 or UV modes
  50        DC_PRED = B_DC_PRED, V_PRED = B_VE_PRED,
  51        H_PRED = B_HE_PRED, TM_PRED = B_TM_PRED,
  52        B_PRED = NUM_BMODES,   // refined I4x4 mode
  53
  54        // special modes
  55        B_DC_PRED_NOTOP = 4,
  56        B_DC_PRED_NOLEFT = 5,
  57        B_DC_PRED_NOTOPLEFT = 6,
  58        NUM_B_DC_MODES = 7 };
  59
  60 enum { MB_FEATURE_TREE_PROBS = 3,
  61        NUM_MB_SEGMENTS = 4,
  62        NUM_REF_LF_DELTAS = 4,
  63        NUM_MODE_LF_DELTAS = 4,    // I4x4, ZERO, *, SPLIT
  64        MAX_NUM_PARTITIONS = 8,
  65        // Probabilities
  66        NUM_TYPES = 4,
  67        NUM_BANDS = 8,
  68        NUM_CTX = 3,
  69        NUM_PROBAS = 11,
  70        NUM_MV_PROBAS = 19 };
  71
  72 // YUV-cache parameters.
  73 // Constraints are: We need to store one 16x16 block of luma samples (y),
  74 // and two 8x8 chroma blocks (u/v). These are better be 16-bytes aligned,
  75 // in order to be SIMD-friendly. We also need to store the top, left and
  76 // top-left samples (from previously decoded blocks), along with four
  77 // extra top-right samples for luma (intra4x4 prediction only).
  78 // One possible layout is, using 32 * (17 + 9) bytes:
  79 //
  80 //   .+------   <- only 1 pixel high
  81 //   .|yyyyt.
  82 //   .|yyyyt.
  83 //   .|yyyyt.
  84 //   .|yyyy..
  85 //   .+--.+--   <- only 1 pixel high
  86 //   .|uu.|vv
  87 //   .|uu.|vv
  88 //
  89 // Every character is a 4x4 block, with legend:
  90 //  '.' = unused
  91 //  'y' = y-samples   'u' = u-samples     'v' = u-samples
  92 //  '|' = left sample,   '-' = top sample,    '+' = top-left sample
  93 //  't' = extra top-right sample for 4x4 modes
  94 // With this layout, BPS (=Bytes Per Scan-line) is one cacheline size.
  95 #define BPS       32    // this is the common stride used by yuv[]
  96 #define YUV_SIZE (BPS * 17 + BPS * 9)
  97 #define Y_SIZE   (BPS * 17)
  98 #define Y_OFF    (BPS * 1 + 8)
  99 #define U_OFF    (Y_OFF + BPS * 16 + BPS)
 100 #define V_OFF    (U_OFF + 16)
 101
 102 // minimal width under which lossy multi-threading is always disabled
 103 #define MIN_WIDTH_FOR_THREADS 512
 104
 105 //------------------------------------------------------------------------------
 106 // Headers
 107
 108 typedef struct {
 109   uint8_t key_frame_;
 110   uint8_t profile_;
 111   uint8_t show_;
 112   uint32_t partition_length_;
 113 } VP8FrameHeader;
 114
 115 typedef struct {
 116   uint16_t width_;
 117   uint16_t height_;
 118   uint8_t xscale_;
 119   uint8_t yscale_;
 120   uint8_t colorspace_;   // 0 = YCbCr
 121   uint8_t clamp_type_;
 122 } VP8PictureHeader;
 123
 124 // segment features
 125 typedef struct {
 126   int use_segment_;
 127   int update_map_;        // whether to update the segment map or not
 128   int absolute_delta_;    // absolute or delta values for quantizer and filter
 129   int8_t quantizer_[NUM_MB_SEGMENTS];        // quantization changes
 130   int8_t filter_strength_[NUM_MB_SEGMENTS];  // filter strength for segments
 131 } VP8SegmentHeader;
 132
 133
 134 // probas associated to one of the contexts
 135 typedef uint8_t VP8ProbaArray[NUM_PROBAS];
 136
 137 typedef struct {   // all the probas associated to one band
 138   VP8ProbaArray probas_[NUM_CTX];
 139 } VP8BandProbas;
 140
 141 // Struct collecting all frame-persistent probabilities.
 142 typedef struct {
 143   uint8_t segments_[MB_FEATURE_TREE_PROBS];
 144   // Type: 0:Intra16-AC  1:Intra16-DC   2:Chroma   3:Intra4
 145   VP8BandProbas bands_[NUM_TYPES][NUM_BANDS];
 146 } VP8Proba;
 147
 148 // Filter parameters
 149 typedef struct {
 150   int simple_;                  // 0=complex, 1=simple
 151   int level_;                   // [0..63]
 152   int sharpness_;               // [0..7]
 153   int use_lf_delta_;
 154   int ref_lf_delta_[NUM_REF_LF_DELTAS];
 155   int mode_lf_delta_[NUM_MODE_LF_DELTAS];
 156 } VP8FilterHeader;
 157
 158 //------------------------------------------------------------------------------
 159 // Informations about the macroblocks.
 160
 161 typedef struct {  // filter specs
 162   uint8_t f_limit_;      // filter limit in [3..189], or 0 if no filtering
 163   uint8_t f_ilevel_;     // inner limit in [1..63]
 164   uint8_t f_inner_;      // do inner filtering?
 165   uint8_t hev_thresh_;   // high edge variance threshold in [0..2]
 166 } VP8FInfo;
 167
 168 typedef struct {  // Top/Left Contexts used for syntax-parsing
 169   uint8_t nz_;        // non-zero AC/DC coeffs (4bit for luma + 4bit for chroma)
 170   uint8_t nz_dc_;     // non-zero DC coeff (1bit)
 171 } VP8MB;
 172
 173 // Dequantization matrices
 174 typedef int quant_t[2];      // [DC / AC].  Can be 'uint16_t[2]' too (~slower).
 175 typedef struct {
 176   quant_t y1_mat_, y2_mat_, uv_mat_;
 177
 178   int uv_quant_;   // U/V quantizer value
 179   int dither_;     // dithering amplitude (0 = off, max=255)
 180 } VP8QuantMatrix;
 181
 182 // Data needed to reconstruct a macroblock
 183 typedef struct {
 184   int16_t coeffs_[384];   // 384 coeffs = (16+4+4) * 4*4
 185   uint8_t is_i4x4_;       // true if intra4x4
 186   uint8_t imodes_[16];    // one 16x16 mode (#0) or sixteen 4x4 modes
 187   uint8_t uvmode_;        // chroma prediction mode
 188   // bit-wise info about the content of each sub-4x4 blocks (in decoding order).
 189   // Each of the 4x4 blocks for y/u/v is associated with a 2b code according to:
 190   //   code=0 -> no coefficient
 191   //   code=1 -> only DC
 192   //   code=2 -> first three coefficients are non-zero
 193   //   code=3 -> more than three coefficients are non-zero
 194   // This allows to call specialized transform functions.
 195   uint32_t non_zero_y_;
 196   uint32_t non_zero_uv_;
 197   uint8_t dither_;      // local dithering strength (deduced from non_zero_*)
 198   uint8_t skip_;
 199   uint8_t segment_;
 200 } VP8MBData;
 201
 202 // Persistent information needed by the parallel processing
 203 typedef struct {
 204   int id_;              // cache row to process (in [0..2])
 205   int mb_y_;            // macroblock position of the row
 206   int filter_row_;      // true if row-filtering is needed
 207   VP8FInfo* f_info_;    // filter strengths (swapped with dec->f_info_)
 208   VP8MBData* mb_data_;  // reconstruction data (swapped with dec->mb_data_)
 209   VP8Io io_;            // copy of the VP8Io to pass to put()
 210 } VP8ThreadContext;
 211
 212 // Saved top samples, per macroblock. Fits into a cache-line.
 213 typedef struct {
 214   uint8_t y[16], u[8], v[8];
 215 } VP8TopSamples;
 216
 217 //------------------------------------------------------------------------------
 218 // VP8Decoder: the main opaque structure handed over to user
 219
 220 struct VP8Decoder {
 221   VP8StatusCode status_;
 222   int ready_;     // true if ready to decode a picture with VP8Decode()
 223   const char* error_msg_;  // set when status_ is not OK.
 224
 225   // Main data source
 226   VP8BitReader br_;
 227
 228   // headers
 229   VP8FrameHeader   frm_hdr_;
 230   VP8PictureHeader pic_hdr_;
 231   VP8FilterHeader  filter_hdr_;
 232   VP8SegmentHeader segment_hdr_;
 233
 234   // Worker
 235   WebPWorker worker_;
 236   int mt_method_;      // multi-thread method: 0=off, 1=[parse+recon][filter]
 237                        // 2=[parse][recon+filter]
 238   int cache_id_;       // current cache row
 239   int num_caches_;     // number of cached rows of 16 pixels (1, 2 or 3)
 240   VP8ThreadContext thread_ctx_;  // Thread context
 241
 242   // dimension, in macroblock units.
 243   int mb_w_, mb_h_;
 244
 245   // Macroblock to process/filter, depending on cropping and filter_type.
 246   int tl_mb_x_, tl_mb_y_;  // top-left MB that must be in-loop filtered
 247   int br_mb_x_, br_mb_y_;  // last bottom-right MB that must be decoded
 248
 249   // number of partitions.
 250   int num_parts_;
 251   // per-partition boolean decoders.
 252   VP8BitReader parts_[MAX_NUM_PARTITIONS];
 253
 254   // Dithering strength, deduced from decoding options
 255   int dither_;                // whether to use dithering or not
 256   VP8Random dithering_rg_;    // random generator for dithering
 257
 258   // dequantization (one set of DC/AC dequant factor per segment)
 259   VP8QuantMatrix dqm_[NUM_MB_SEGMENTS];
 260
 261   // probabilities
 262   VP8Proba proba_;
 263   int use_skip_proba_;
 264   uint8_t skip_p_;
 265
 266   // Boundary data cache and persistent buffers.
 267   uint8_t* intra_t_;      // top intra modes values: 4 * mb_w_
 268   uint8_t  intra_l_[4];   // left intra modes values
 269
 270   VP8TopSamples* yuv_t_;  // top y/u/v samples
 271
 272   VP8MB* mb_info_;        // contextual macroblock info (mb_w_ + 1)
 273   VP8FInfo* f_info_;      // filter strength info
 274   uint8_t* yuv_b_;        // main block for Y/U/V (size = YUV_SIZE)
 275
 276   uint8_t* cache_y_;      // macroblock row for storing unfiltered samples
 277   uint8_t* cache_u_;
 278   uint8_t* cache_v_;
 279   int cache_y_stride_;
 280   int cache_uv_stride_;
 281
 282   // main memory chunk for the above data. Persistent.
 283   void* mem_;
 284   size_t mem_size_;
 285
 286   // Per macroblock non-persistent infos.
 287   int mb_x_, mb_y_;       // current position, in macroblock units
 288   VP8MBData* mb_data_;    // parsed reconstruction data
 289
 290   // Filtering side-info
 291   int filter_type_;                          // 0=off, 1=simple, 2=complex
 292   VP8FInfo fstrengths_[NUM_MB_SEGMENTS][2];  // precalculated per-segment/type
 293
 294   // Alpha
 295   struct ALPHDecoder* alph_dec_;  // alpha-plane decoder object
 296   const uint8_t* alpha_data_;     // compressed alpha data (if present)
 297   size_t alpha_data_size_;
 298   int is_alpha_decoded_;  // true if alpha_data_ is decoded in alpha_plane_
 299   uint8_t* alpha_plane_;  // output. Persistent, contains the whole data.
 300   int alpha_dithering_;   // derived from decoding options (0=off, 100=full).
 301 };
 302
 303 //------------------------------------------------------------------------------
 304 // internal functions. Not public.
 305
 306 // in vp8.c
 307 int VP8SetError(VP8Decoder* const dec,
 308                 VP8StatusCode error, const char* const msg);
 309
 310 // in tree.c
 311 void VP8ResetProba(VP8Proba* const proba);
 312 void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec);
 313 // parses one row of intra mode data in partition 0, returns !eof
 314 int VP8ParseIntraModeRow(VP8BitReader* const br, VP8Decoder* const dec);
 315
 316 // in quant.c
 317 void VP8ParseQuant(VP8Decoder* const dec);
 318
 319 // in frame.c
 320 int VP8InitFrame(VP8Decoder* const dec, VP8Io* io);
 321 // Call io->setup() and finish setting up scan parameters.
 322 // After this call returns, one must always call VP8ExitCritical() with the
 323 // same parameters. Both functions should be used in pair. Returns VP8_STATUS_OK
 324 // if ok, otherwise sets and returns the error status on *dec.
 325 VP8StatusCode VP8EnterCritical(VP8Decoder* const dec, VP8Io* const io);
 326 // Must always be called in pair with VP8EnterCritical().
 327 // Returns false in case of error.
 328 int VP8ExitCritical(VP8Decoder* const dec, VP8Io* const io);
 329 // Return the multi-threading method to use (0=off), depending
 330 // on options and bitstream size. Only for lossy decoding.
 331 int VP8GetThreadMethod(const WebPDecoderOptions* const options,
 332                        const WebPHeaderStructure* const headers,
 333                        int width, int height);
 334 // Initialize dithering post-process if needed.
 335 void VP8InitDithering(const WebPDecoderOptions* const options,
 336                       VP8Decoder* const dec);
 337 // Process the last decoded row (filtering + output).
 338 int VP8ProcessRow(VP8Decoder* const dec, VP8Io* const io);
 339 // To be called at the start of a new scanline, to initialize predictors.
 340 void VP8InitScanline(VP8Decoder* const dec);
 341 // Decode one macroblock. Returns false if there is not enough data.
 342 int VP8DecodeMB(VP8Decoder* const dec, VP8BitReader* const token_br);
 343
 344 // in alpha.c
 345 const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
 346                                       int row, int num_rows);
 347
 348 //------------------------------------------------------------------------------
 349
 350 #ifdef __cplusplus
 351 }    // extern "C"
 352 #endif
 353
 354 #endif  /* WEBP_DEC_VP8I_H_ */