libwebp-0.6.0-rc1

third_party/libwebp/dec/vp8i.h

-// Copyright 2010 Google Inc. All Rights Reserved.
-//
-// Use of this source code is governed by a BSD-style license
-// that can be found in the COPYING file in the root of the source
-// tree. An additional intellectual property rights grant can be found
-// in the file PATENTS. All contributing project authors may
-// be found in the AUTHORS file in the root of the source tree.
-// -----------------------------------------------------------------------------
-//
-// VP8 decoder: internal header.
-//
-// Author: Skal (pascal.massimino@gmail.com)
-
-#ifndef WEBP_DEC_VP8I_H_
-#define WEBP_DEC_VP8I_H_
-
-#include <string.h>     // for memcpy()
-#include "./common.h"
-#include "./vp8li.h"
-#include "../utils/bit_reader.h"
-#include "../utils/random.h"
-#include "../utils/thread.h"
-#include "../dsp/dsp.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-//------------------------------------------------------------------------------
-// Various defines and enums
-
-// version numbers
-#define DEC_MAJ_VERSION 0
-#define DEC_MIN_VERSION 5
-#define DEC_REV_VERSION 2
-
-// YUV-cache parameters. Cache is 32-bytes wide (= one cacheline).
-// Constraints are: We need to store one 16x16 block of luma samples (y),
-// and two 8x8 chroma blocks (u/v). These are better be 16-bytes aligned,
-// in order to be SIMD-friendly. We also need to store the top, left and
-// top-left samples (from previously decoded blocks), along with four
-// extra top-right samples for luma (intra4x4 prediction only).
-// One possible layout is, using 32 * (17 + 9) bytes:
-//
-//   .+------   <- only 1 pixel high
-//   .|yyyyt.
-//   .|yyyyt.
-//   .|yyyyt.
-//   .|yyyy..
-//   .+--.+--   <- only 1 pixel high
-//   .|uu.|vv
-//   .|uu.|vv
-//
-// Every character is a 4x4 block, with legend:
-//  '.' = unused
-//  'y' = y-samples   'u' = u-samples     'v' = u-samples
-//  '|' = left sample,   '-' = top sample,    '+' = top-left sample
-//  't' = extra top-right sample for 4x4 modes
-#define YUV_SIZE (BPS * 17 + BPS * 9)
-#define Y_SIZE   (BPS * 17)
-#define Y_OFF    (BPS * 1 + 8)
-#define U_OFF    (Y_OFF + BPS * 16 + BPS)
-#define V_OFF    (U_OFF + 16)
-
-// minimal width under which lossy multi-threading is always disabled
-#define MIN_WIDTH_FOR_THREADS 512
-
-//------------------------------------------------------------------------------
-// Headers
-
-typedef struct {
-  uint8_t key_frame_;
-  uint8_t profile_;
-  uint8_t show_;
-  uint32_t partition_length_;
-} VP8FrameHeader;
-
-typedef struct {
-  uint16_t width_;
-  uint16_t height_;
-  uint8_t xscale_;
-  uint8_t yscale_;
-  uint8_t colorspace_;   // 0 = YCbCr
-  uint8_t clamp_type_;
-} VP8PictureHeader;
-
-// segment features
-typedef struct {
-  int use_segment_;
-  int update_map_;        // whether to update the segment map or not
-  int absolute_delta_;    // absolute or delta values for quantizer and filter
-  int8_t quantizer_[NUM_MB_SEGMENTS];        // quantization changes
-  int8_t filter_strength_[NUM_MB_SEGMENTS];  // filter strength for segments
-} VP8SegmentHeader;
-
-// probas associated to one of the contexts
-typedef uint8_t VP8ProbaArray[NUM_PROBAS];
-
-typedef struct {   // all the probas associated to one band
-  VP8ProbaArray probas_[NUM_CTX];
-} VP8BandProbas;
-
-// Struct collecting all frame-persistent probabilities.
-typedef struct {
-  uint8_t segments_[MB_FEATURE_TREE_PROBS];
-  // Type: 0:Intra16-AC  1:Intra16-DC   2:Chroma   3:Intra4
-  VP8BandProbas bands_[NUM_TYPES][NUM_BANDS];
-  const VP8BandProbas* bands_ptr_[NUM_TYPES][16 + 1];
-} VP8Proba;
-
-// Filter parameters
-typedef struct {
-  int simple_;                  // 0=complex, 1=simple
-  int level_;                   // [0..63]
-  int sharpness_;               // [0..7]
-  int use_lf_delta_;
-  int ref_lf_delta_[NUM_REF_LF_DELTAS];
-  int mode_lf_delta_[NUM_MODE_LF_DELTAS];
-} VP8FilterHeader;
-
-//------------------------------------------------------------------------------
-// Informations about the macroblocks.
-
-typedef struct {  // filter specs
-  uint8_t f_limit_;      // filter limit in [3..189], or 0 if no filtering
-  uint8_t f_ilevel_;     // inner limit in [1..63]
-  uint8_t f_inner_;      // do inner filtering?
-  uint8_t hev_thresh_;   // high edge variance threshold in [0..2]
-} VP8FInfo;
-
-typedef struct {  // Top/Left Contexts used for syntax-parsing
-  uint8_t nz_;        // non-zero AC/DC coeffs (4bit for luma + 4bit for chroma)
-  uint8_t nz_dc_;     // non-zero DC coeff (1bit)
-} VP8MB;
-
-// Dequantization matrices
-typedef int quant_t[2];      // [DC / AC].  Can be 'uint16_t[2]' too (~slower).
-typedef struct {
-  quant_t y1_mat_, y2_mat_, uv_mat_;
-
-  int uv_quant_;   // U/V quantizer value
-  int dither_;     // dithering amplitude (0 = off, max=255)
-} VP8QuantMatrix;
-
-// Data needed to reconstruct a macroblock
-typedef struct {
-  int16_t coeffs_[384];   // 384 coeffs = (16+4+4) * 4*4
-  uint8_t is_i4x4_;       // true if intra4x4
-  uint8_t imodes_[16];    // one 16x16 mode (#0) or sixteen 4x4 modes
-  uint8_t uvmode_;        // chroma prediction mode
-  // bit-wise info about the content of each sub-4x4 blocks (in decoding order).
-  // Each of the 4x4 blocks for y/u/v is associated with a 2b code according to:
-  //   code=0 -> no coefficient
-  //   code=1 -> only DC
-  //   code=2 -> first three coefficients are non-zero
-  //   code=3 -> more than three coefficients are non-zero
-  // This allows to call specialized transform functions.
-  uint32_t non_zero_y_;
-  uint32_t non_zero_uv_;
-  uint8_t dither_;      // local dithering strength (deduced from non_zero_*)
-  uint8_t skip_;
-  uint8_t segment_;
-} VP8MBData;
-
-// Persistent information needed by the parallel processing
-typedef struct {
-  int id_;              // cache row to process (in [0..2])
-  int mb_y_;            // macroblock position of the row
-  int filter_row_;      // true if row-filtering is needed
-  VP8FInfo* f_info_;    // filter strengths (swapped with dec->f_info_)
-  VP8MBData* mb_data_;  // reconstruction data (swapped with dec->mb_data_)
-  VP8Io io_;            // copy of the VP8Io to pass to put()
-} VP8ThreadContext;
-
-// Saved top samples, per macroblock. Fits into a cache-line.
-typedef struct {
-  uint8_t y[16], u[8], v[8];
-} VP8TopSamples;
-
-//------------------------------------------------------------------------------
-// VP8Decoder: the main opaque structure handed over to user
-
-struct VP8Decoder {
-  VP8StatusCode status_;
-  int ready_;     // true if ready to decode a picture with VP8Decode()
-  const char* error_msg_;  // set when status_ is not OK.
-
-  // Main data source
-  VP8BitReader br_;
-
-  // headers
-  VP8FrameHeader   frm_hdr_;
-  VP8PictureHeader pic_hdr_;
-  VP8FilterHeader  filter_hdr_;
-  VP8SegmentHeader segment_hdr_;
-
-  // Worker
-  WebPWorker worker_;
-  int mt_method_;      // multi-thread method: 0=off, 1=[parse+recon][filter]
-                       // 2=[parse][recon+filter]
-  int cache_id_;       // current cache row
-  int num_caches_;     // number of cached rows of 16 pixels (1, 2 or 3)
-  VP8ThreadContext thread_ctx_;  // Thread context
-
-  // dimension, in macroblock units.
-  int mb_w_, mb_h_;
-
-  // Macroblock to process/filter, depending on cropping and filter_type.
-  int tl_mb_x_, tl_mb_y_;  // top-left MB that must be in-loop filtered
-  int br_mb_x_, br_mb_y_;  // last bottom-right MB that must be decoded
-
-  // number of partitions minus one.
-  uint32_t num_parts_minus_one_;
-  // per-partition boolean decoders.
-  VP8BitReader parts_[MAX_NUM_PARTITIONS];
-
-  // Dithering strength, deduced from decoding options
-  int dither_;                // whether to use dithering or not
-  VP8Random dithering_rg_;    // random generator for dithering
-
-  // dequantization (one set of DC/AC dequant factor per segment)
-  VP8QuantMatrix dqm_[NUM_MB_SEGMENTS];
-
-  // probabilities
-  VP8Proba proba_;
-  int use_skip_proba_;
-  uint8_t skip_p_;
-
-  // Boundary data cache and persistent buffers.
-  uint8_t* intra_t_;      // top intra modes values: 4 * mb_w_
-  uint8_t  intra_l_[4];   // left intra modes values
-
-  VP8TopSamples* yuv_t_;  // top y/u/v samples
-
-  VP8MB* mb_info_;        // contextual macroblock info (mb_w_ + 1)
-  VP8FInfo* f_info_;      // filter strength info
-  uint8_t* yuv_b_;        // main block for Y/U/V (size = YUV_SIZE)
-
-  uint8_t* cache_y_;      // macroblock row for storing unfiltered samples
-  uint8_t* cache_u_;
-  uint8_t* cache_v_;
-  int cache_y_stride_;
-  int cache_uv_stride_;
-
-  // main memory chunk for the above data. Persistent.
-  void* mem_;
-  size_t mem_size_;
-
-  // Per macroblock non-persistent infos.
-  int mb_x_, mb_y_;       // current position, in macroblock units
-  VP8MBData* mb_data_;    // parsed reconstruction data
-
-  // Filtering side-info
-  int filter_type_;                          // 0=off, 1=simple, 2=complex
-  VP8FInfo fstrengths_[NUM_MB_SEGMENTS][2];  // precalculated per-segment/type
-
-  // Alpha
-  struct ALPHDecoder* alph_dec_;  // alpha-plane decoder object
-  const uint8_t* alpha_data_;     // compressed alpha data (if present)
-  size_t alpha_data_size_;
-  int is_alpha_decoded_;      // true if alpha_data_ is decoded in alpha_plane_
-  uint8_t* alpha_plane_mem_;  // memory allocated for alpha_plane_
-  uint8_t* alpha_plane_;      // output. Persistent, contains the whole data.
-  const uint8_t* alpha_prev_line_;  // last decoded alpha row (or NULL)
-  int alpha_dithering_;       // derived from decoding options (0=off, 100=full)
-};
-
-//------------------------------------------------------------------------------
-// internal functions. Not public.
-
-// in vp8.c
-int VP8SetError(VP8Decoder* const dec,
-                VP8StatusCode error, const char* const msg);
-
-// in tree.c
-void VP8ResetProba(VP8Proba* const proba);
-void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec);
-// parses one row of intra mode data in partition 0, returns !eof
-int VP8ParseIntraModeRow(VP8BitReader* const br, VP8Decoder* const dec);
-
-// in quant.c
-void VP8ParseQuant(VP8Decoder* const dec);
-
-// in frame.c
-int VP8InitFrame(VP8Decoder* const dec, VP8Io* const io);
-// Call io->setup() and finish setting up scan parameters.
-// After this call returns, one must always call VP8ExitCritical() with the
-// same parameters. Both functions should be used in pair. Returns VP8_STATUS_OK
-// if ok, otherwise sets and returns the error status on *dec.
-VP8StatusCode VP8EnterCritical(VP8Decoder* const dec, VP8Io* const io);
-// Must always be called in pair with VP8EnterCritical().
-// Returns false in case of error.
-int VP8ExitCritical(VP8Decoder* const dec, VP8Io* const io);
-// Return the multi-threading method to use (0=off), depending
-// on options and bitstream size. Only for lossy decoding.
-int VP8GetThreadMethod(const WebPDecoderOptions* const options,
-                       const WebPHeaderStructure* const headers,
-                       int width, int height);
-// Initialize dithering post-process if needed.
-void VP8InitDithering(const WebPDecoderOptions* const options,
-                      VP8Decoder* const dec);
-// Process the last decoded row (filtering + output).
-int VP8ProcessRow(VP8Decoder* const dec, VP8Io* const io);
-// To be called at the start of a new scanline, to initialize predictors.
-void VP8InitScanline(VP8Decoder* const dec);
-// Decode one macroblock. Returns false if there is not enough data.
-int VP8DecodeMB(VP8Decoder* const dec, VP8BitReader* const token_br);
-
-// in alpha.c
-const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
-                                      const VP8Io* const io,
-                                      int row, int num_rows);
-
-//------------------------------------------------------------------------------
-
-#ifdef __cplusplus
-}    // extern "C"
-#endif
-
-#endif  /* WEBP_DEC_VP8I_H_ */