355 lines
12 KiB
C
355 lines
12 KiB
C
// Copyright 2010 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// VP8 decoder: internal header.
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#ifndef WEBP_DEC_VP8I_H_
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#define WEBP_DEC_VP8I_H_
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#include <string.h> // for memcpy()
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#include "./vp8li.h"
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#include "../utils/bit_reader.h"
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#include "../utils/random.h"
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#include "../utils/thread.h"
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#include "../dsp/dsp.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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//------------------------------------------------------------------------------
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// Various defines and enums
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// version numbers
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#define DEC_MAJ_VERSION 0
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#define DEC_MIN_VERSION 4
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#define DEC_REV_VERSION 2
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// intra prediction modes
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enum { B_DC_PRED = 0, // 4x4 modes
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B_TM_PRED,
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B_VE_PRED,
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B_HE_PRED,
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B_RD_PRED,
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B_VR_PRED,
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B_LD_PRED,
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B_VL_PRED,
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B_HD_PRED,
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B_HU_PRED,
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NUM_BMODES = B_HU_PRED + 1 - B_DC_PRED, // = 10
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// Luma16 or UV modes
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DC_PRED = B_DC_PRED, V_PRED = B_VE_PRED,
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H_PRED = B_HE_PRED, TM_PRED = B_TM_PRED,
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B_PRED = NUM_BMODES, // refined I4x4 mode
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// special modes
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B_DC_PRED_NOTOP = 4,
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B_DC_PRED_NOLEFT = 5,
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B_DC_PRED_NOTOPLEFT = 6,
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NUM_B_DC_MODES = 7 };
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enum { MB_FEATURE_TREE_PROBS = 3,
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NUM_MB_SEGMENTS = 4,
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NUM_REF_LF_DELTAS = 4,
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NUM_MODE_LF_DELTAS = 4, // I4x4, ZERO, *, SPLIT
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MAX_NUM_PARTITIONS = 8,
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// Probabilities
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NUM_TYPES = 4,
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NUM_BANDS = 8,
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NUM_CTX = 3,
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NUM_PROBAS = 11,
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NUM_MV_PROBAS = 19 };
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// YUV-cache parameters.
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// Constraints are: We need to store one 16x16 block of luma samples (y),
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// and two 8x8 chroma blocks (u/v). These are better be 16-bytes aligned,
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// in order to be SIMD-friendly. We also need to store the top, left and
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// top-left samples (from previously decoded blocks), along with four
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// extra top-right samples for luma (intra4x4 prediction only).
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// One possible layout is, using 32 * (17 + 9) bytes:
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//
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// .+------ <- only 1 pixel high
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// .|yyyyt.
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// .|yyyyt.
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// .|yyyyt.
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// .|yyyy..
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// .+--.+-- <- only 1 pixel high
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// .|uu.|vv
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// .|uu.|vv
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//
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// Every character is a 4x4 block, with legend:
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// '.' = unused
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// 'y' = y-samples 'u' = u-samples 'v' = u-samples
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// '|' = left sample, '-' = top sample, '+' = top-left sample
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// 't' = extra top-right sample for 4x4 modes
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// With this layout, BPS (=Bytes Per Scan-line) is one cacheline size.
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#define BPS 32 // this is the common stride used by yuv[]
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#define YUV_SIZE (BPS * 17 + BPS * 9)
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#define Y_SIZE (BPS * 17)
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#define Y_OFF (BPS * 1 + 8)
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#define U_OFF (Y_OFF + BPS * 16 + BPS)
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#define V_OFF (U_OFF + 16)
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// minimal width under which lossy multi-threading is always disabled
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#define MIN_WIDTH_FOR_THREADS 512
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//------------------------------------------------------------------------------
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// Headers
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typedef struct {
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uint8_t key_frame_;
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uint8_t profile_;
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uint8_t show_;
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uint32_t partition_length_;
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} VP8FrameHeader;
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typedef struct {
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uint16_t width_;
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uint16_t height_;
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uint8_t xscale_;
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uint8_t yscale_;
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uint8_t colorspace_; // 0 = YCbCr
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uint8_t clamp_type_;
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} VP8PictureHeader;
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// segment features
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typedef struct {
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int use_segment_;
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int update_map_; // whether to update the segment map or not
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int absolute_delta_; // absolute or delta values for quantizer and filter
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int8_t quantizer_[NUM_MB_SEGMENTS]; // quantization changes
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int8_t filter_strength_[NUM_MB_SEGMENTS]; // filter strength for segments
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} VP8SegmentHeader;
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// probas associated to one of the contexts
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typedef uint8_t VP8ProbaArray[NUM_PROBAS];
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typedef struct { // all the probas associated to one band
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VP8ProbaArray probas_[NUM_CTX];
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} VP8BandProbas;
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// Struct collecting all frame-persistent probabilities.
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typedef struct {
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uint8_t segments_[MB_FEATURE_TREE_PROBS];
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// Type: 0:Intra16-AC 1:Intra16-DC 2:Chroma 3:Intra4
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VP8BandProbas bands_[NUM_TYPES][NUM_BANDS];
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} VP8Proba;
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// Filter parameters
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typedef struct {
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int simple_; // 0=complex, 1=simple
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int level_; // [0..63]
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int sharpness_; // [0..7]
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int use_lf_delta_;
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int ref_lf_delta_[NUM_REF_LF_DELTAS];
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int mode_lf_delta_[NUM_MODE_LF_DELTAS];
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} VP8FilterHeader;
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//------------------------------------------------------------------------------
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// Informations about the macroblocks.
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typedef struct { // filter specs
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uint8_t f_limit_; // filter limit in [3..189], or 0 if no filtering
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uint8_t f_ilevel_; // inner limit in [1..63]
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uint8_t f_inner_; // do inner filtering?
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uint8_t hev_thresh_; // high edge variance threshold in [0..2]
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} VP8FInfo;
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typedef struct { // Top/Left Contexts used for syntax-parsing
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uint8_t nz_; // non-zero AC/DC coeffs (4bit for luma + 4bit for chroma)
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uint8_t nz_dc_; // non-zero DC coeff (1bit)
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} VP8MB;
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// Dequantization matrices
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typedef int quant_t[2]; // [DC / AC]. Can be 'uint16_t[2]' too (~slower).
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typedef struct {
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quant_t y1_mat_, y2_mat_, uv_mat_;
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int uv_quant_; // U/V quantizer value
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int dither_; // dithering amplitude (0 = off, max=255)
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} VP8QuantMatrix;
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// Data needed to reconstruct a macroblock
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typedef struct {
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int16_t coeffs_[384]; // 384 coeffs = (16+4+4) * 4*4
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uint8_t is_i4x4_; // true if intra4x4
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uint8_t imodes_[16]; // one 16x16 mode (#0) or sixteen 4x4 modes
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uint8_t uvmode_; // chroma prediction mode
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// bit-wise info about the content of each sub-4x4 blocks (in decoding order).
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// Each of the 4x4 blocks for y/u/v is associated with a 2b code according to:
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// code=0 -> no coefficient
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// code=1 -> only DC
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// code=2 -> first three coefficients are non-zero
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// code=3 -> more than three coefficients are non-zero
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// This allows to call specialized transform functions.
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uint32_t non_zero_y_;
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uint32_t non_zero_uv_;
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uint8_t dither_; // local dithering strength (deduced from non_zero_*)
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uint8_t skip_;
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uint8_t segment_;
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} VP8MBData;
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// Persistent information needed by the parallel processing
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typedef struct {
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int id_; // cache row to process (in [0..2])
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int mb_y_; // macroblock position of the row
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int filter_row_; // true if row-filtering is needed
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VP8FInfo* f_info_; // filter strengths (swapped with dec->f_info_)
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VP8MBData* mb_data_; // reconstruction data (swapped with dec->mb_data_)
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VP8Io io_; // copy of the VP8Io to pass to put()
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} VP8ThreadContext;
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// Saved top samples, per macroblock. Fits into a cache-line.
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typedef struct {
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uint8_t y[16], u[8], v[8];
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} VP8TopSamples;
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//------------------------------------------------------------------------------
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// VP8Decoder: the main opaque structure handed over to user
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struct VP8Decoder {
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VP8StatusCode status_;
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int ready_; // true if ready to decode a picture with VP8Decode()
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const char* error_msg_; // set when status_ is not OK.
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// Main data source
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VP8BitReader br_;
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// headers
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VP8FrameHeader frm_hdr_;
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VP8PictureHeader pic_hdr_;
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VP8FilterHeader filter_hdr_;
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VP8SegmentHeader segment_hdr_;
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// Worker
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WebPWorker worker_;
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int mt_method_; // multi-thread method: 0=off, 1=[parse+recon][filter]
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// 2=[parse][recon+filter]
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int cache_id_; // current cache row
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int num_caches_; // number of cached rows of 16 pixels (1, 2 or 3)
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VP8ThreadContext thread_ctx_; // Thread context
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// dimension, in macroblock units.
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int mb_w_, mb_h_;
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// Macroblock to process/filter, depending on cropping and filter_type.
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int tl_mb_x_, tl_mb_y_; // top-left MB that must be in-loop filtered
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int br_mb_x_, br_mb_y_; // last bottom-right MB that must be decoded
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// number of partitions.
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int num_parts_;
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// per-partition boolean decoders.
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VP8BitReader parts_[MAX_NUM_PARTITIONS];
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// Dithering strength, deduced from decoding options
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int dither_; // whether to use dithering or not
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VP8Random dithering_rg_; // random generator for dithering
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// dequantization (one set of DC/AC dequant factor per segment)
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VP8QuantMatrix dqm_[NUM_MB_SEGMENTS];
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// probabilities
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VP8Proba proba_;
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int use_skip_proba_;
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uint8_t skip_p_;
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// Boundary data cache and persistent buffers.
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uint8_t* intra_t_; // top intra modes values: 4 * mb_w_
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uint8_t intra_l_[4]; // left intra modes values
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VP8TopSamples* yuv_t_; // top y/u/v samples
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VP8MB* mb_info_; // contextual macroblock info (mb_w_ + 1)
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VP8FInfo* f_info_; // filter strength info
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uint8_t* yuv_b_; // main block for Y/U/V (size = YUV_SIZE)
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uint8_t* cache_y_; // macroblock row for storing unfiltered samples
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uint8_t* cache_u_;
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uint8_t* cache_v_;
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int cache_y_stride_;
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int cache_uv_stride_;
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// main memory chunk for the above data. Persistent.
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void* mem_;
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size_t mem_size_;
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// Per macroblock non-persistent infos.
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int mb_x_, mb_y_; // current position, in macroblock units
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VP8MBData* mb_data_; // parsed reconstruction data
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// Filtering side-info
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int filter_type_; // 0=off, 1=simple, 2=complex
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VP8FInfo fstrengths_[NUM_MB_SEGMENTS][2]; // precalculated per-segment/type
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// Alpha
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struct ALPHDecoder* alph_dec_; // alpha-plane decoder object
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const uint8_t* alpha_data_; // compressed alpha data (if present)
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size_t alpha_data_size_;
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int is_alpha_decoded_; // true if alpha_data_ is decoded in alpha_plane_
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uint8_t* alpha_plane_; // output. Persistent, contains the whole data.
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int alpha_dithering_; // derived from decoding options (0=off, 100=full).
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};
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//------------------------------------------------------------------------------
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// internal functions. Not public.
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// in vp8.c
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int VP8SetError(VP8Decoder* const dec,
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VP8StatusCode error, const char* const msg);
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// in tree.c
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void VP8ResetProba(VP8Proba* const proba);
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void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec);
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// parses one row of intra mode data in partition 0, returns !eof
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int VP8ParseIntraModeRow(VP8BitReader* const br, VP8Decoder* const dec);
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// in quant.c
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void VP8ParseQuant(VP8Decoder* const dec);
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// in frame.c
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int VP8InitFrame(VP8Decoder* const dec, VP8Io* io);
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// Call io->setup() and finish setting up scan parameters.
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// After this call returns, one must always call VP8ExitCritical() with the
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// same parameters. Both functions should be used in pair. Returns VP8_STATUS_OK
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// if ok, otherwise sets and returns the error status on *dec.
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VP8StatusCode VP8EnterCritical(VP8Decoder* const dec, VP8Io* const io);
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// Must always be called in pair with VP8EnterCritical().
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// Returns false in case of error.
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int VP8ExitCritical(VP8Decoder* const dec, VP8Io* const io);
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// Return the multi-threading method to use (0=off), depending
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// on options and bitstream size. Only for lossy decoding.
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int VP8GetThreadMethod(const WebPDecoderOptions* const options,
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const WebPHeaderStructure* const headers,
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int width, int height);
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// Initialize dithering post-process if needed.
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void VP8InitDithering(const WebPDecoderOptions* const options,
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VP8Decoder* const dec);
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// Process the last decoded row (filtering + output).
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int VP8ProcessRow(VP8Decoder* const dec, VP8Io* const io);
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// To be called at the start of a new scanline, to initialize predictors.
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void VP8InitScanline(VP8Decoder* const dec);
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// Decode one macroblock. Returns false if there is not enough data.
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int VP8DecodeMB(VP8Decoder* const dec, VP8BitReader* const token_br);
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// in alpha.c
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const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
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int row, int num_rows);
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//------------------------------------------------------------------------------
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif /* WEBP_DEC_VP8I_H_ */
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