vp8i_dec.h | Explore in Territory

// 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 ([email protected])

#ifndef WEBP_DEC_VP8I_DEC_H_
#define WEBP_DEC_VP8I_DEC_H_

#include <string.h>     // for memcpy()
#include "src/dec/common_dec.h"
#include "src/dec/vp8li_dec.h"
#include "src/utils/bit_reader_utils.h"
#include "src/utils/random_utils.h"
#include "src/utils/thread_utils.h"
#include "src/dsp/dsp.h"
#include "src/webp/types.h"

#ifdef __cplusplus
extern "C" {
#endif

//------------------------------------------------------------------------------
// Various defines and enums

// version numbers
#define DEC_MAJ_VERSION …
#define DEC_MIN_VERSION …
#define DEC_REV_VERSION …

// 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 …
#define Y_OFF …
#define U_OFF …
#define V_OFF …

// minimal width under which lossy multi-threading is always disabled
#define MIN_WIDTH_FOR_THREADS …

//------------------------------------------------------------------------------
// Headers

VP8FrameHeader;

VP8PictureHeader;

// segment features
VP8SegmentHeader;

// probas associated to one of the contexts
VP8ProbaArray;

VP8BandProbas;

// Struct collecting all frame-persistent probabilities.
VP8Proba;

// Filter parameters
VP8FilterHeader;

//------------------------------------------------------------------------------
// Informations about the macroblocks.

VP8FInfo;

VP8MB;

// Dequantization matrices
quant_t;      // [DC / AC].  Can be 'uint16_t[2]' too (~slower).
VP8QuantMatrix;

// Data needed to reconstruct a macroblock
VP8MBData;

// Persistent information needed by the parallel processing
VP8ThreadContext;

// Saved top samples, per macroblock. Fits into a cache-line.
VP8TopSamples;

//------------------------------------------------------------------------------
// VP8Decoder: the main opaque structure handed over to user

struct VP8Decoder { … };

//------------------------------------------------------------------------------
// 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
WEBP_NODISCARD 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.
WEBP_NODISCARD 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).
WEBP_NODISCARD 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.
WEBP_NODISCARD 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_DEC_H_
godot/thirdparty/libwebp/src/dec/vp8i_dec.h
