format.h

在x86平台上运行不可信任代码的sandbox。

/* libFLAC - Free Lossless Audio Codec library
 * Copyright (C) 2000,2001,2002,2003,2004,2005  Josh Coalson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Xiph.org Foundation nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef FLAC__FORMAT_H
#define FLAC__FORMAT_H

#include "export.h"
#include "ordinals.h"

#ifdef __cplusplus
extern "C" {
#endif

/** \file include/FLAC/format.h
 *
 *  \brief
 *  This module contains structure definitions for the representation
 *  of FLAC format components in memory.  These are the basic
 *  structures used by the rest of the interfaces.
 *
 *  See the detailed documentation in the
 *  \link flac_format format \endlink module.
 */

/** \defgroup flac_format FLAC/format.h: format components
 *  \ingroup flac
 *
 *  \brief
 *  This module contains structure definitions for the representation
 *  of FLAC format components in memory.  These are the basic
 *  structures used by the rest of the interfaces.
 *
 *  First, you should be familiar with the
 *  <A HREF="../format.html">FLAC format</A>.  Many of the values here
 *  follow directly from the specification.  As a user of libFLAC, the
 *  interesting parts really are the structures that describe the frame
 *  header and metadata blocks.
 *
 *  The format structures here are very primitive, designed to store
 *  information in an efficient way.  Reading information from the
 *  structures is easy but creating or modifying them directly is
 *  more complex.  For the most part, as a user of a library, editing
 *  is not necessary; however, for metadata blocks it is, so there are
 *  convenience functions provided in the \link flac_metadata metadata
 *  module \endlink to simplify the manipulation of metadata blocks.
 *
 * \note
 * It's not the best convention, but symbols ending in _LEN are in bits
 * and _LENGTH are in bytes.  _LENGTH symbols are \#defines instead of
 * global variables because they are usually used when declaring byte
 * arrays and some compilers require compile-time knowledge of array
 * sizes when declared on the stack.
 *
 * \{
 */


/*
	Most of the values described in this file are defined by the FLAC
	format specification.  There is nothing to tune here.
*/

/** The largest legal metadata type code. */
#define FLAC__MAX_METADATA_TYPE_CODE (126u)

/** The minimum block size, in samples, permitted by the format. */
#define FLAC__MIN_BLOCK_SIZE (16u)

/** The maximum block size, in samples, permitted by the format. */
#define FLAC__MAX_BLOCK_SIZE (65535u)

/** The maximum number of channels permitted by the format. */
#define FLAC__MAX_CHANNELS (8u)

/** The minimum sample resolution permitted by the format. */
#define FLAC__MIN_BITS_PER_SAMPLE (4u)

/** The maximum sample resolution permitted by the format. */
#define FLAC__MAX_BITS_PER_SAMPLE (32u)

/** The maximum sample resolution permitted by libFLAC.
 *
 * \warning
 * FLAC__MAX_BITS_PER_SAMPLE is the limit of the FLAC format.  However,
 * the reference encoder/decoder is currently limited to 24 bits because
 * of prevalent 32-bit math, so make sure and use this value when
 * appropriate.
 */
#define FLAC__REFERENCE_CODEC_MAX_BITS_PER_SAMPLE (24u)

/** The maximum sample rate permitted by the format.  The value is
 *  ((2 ^ 16) - 1) * 10; see <A HREF="../format.html">FLAC format</A>
 *  as to why.
 */
#define FLAC__MAX_SAMPLE_RATE (655350u)

/** The maximum LPC order permitted by the format. */
#define FLAC__MAX_LPC_ORDER (32u)

/** The minimum quantized linear predictor coefficient precision
 *  permitted by the format.
 */
#define FLAC__MIN_QLP_COEFF_PRECISION (5u)

/** The maximum quantized linear predictor coefficient precision
 *  permitted by the format.
 */
#define FLAC__MAX_QLP_COEFF_PRECISION (15u)

/** The maximum order of the fixed predictors permitted by the format. */
#define FLAC__MAX_FIXED_ORDER (4u)

/** The maximum Rice partition order permitted by the format. */
#define FLAC__MAX_RICE_PARTITION_ORDER (15u)

/** The maximum Rice partition order permitted by the FLAC Subset. */
#define FLAC__SUBSET_MAX_RICE_PARTITION_ORDER (8u)

/** The version string of the release, stamped onto the libraries and binaries.
 *
 * \note
 * This does not correspond to the shared library version number, which
 * is used to determine binary compatibility.
 */
extern FLAC_API const char *FLAC__VERSION_STRING;

/** The vendor string inserted by the encoder into the VORBIS_COMMENT block.
 *  This is a nulL-terminated ASCII string; when inserted into the
 *  VORBIS_COMMENT the trailing null is stripped.
 */
extern FLAC_API const char *FLAC__VENDOR_STRING;

/** The byte string representation of the beginning of a FLAC stream. */
extern FLAC_API const FLAC__byte FLAC__STREAM_SYNC_STRING[4]; /* = "fLaC" */

/** The 32-bit integer big-endian representation of the beginning of
 *  a FLAC stream.
 */
extern FLAC_API const unsigned FLAC__STREAM_SYNC; /* = 0x664C6143 */

/** The length of the FLAC signature in bits. */
extern FLAC_API const unsigned FLAC__STREAM_SYNC_LEN; /* = 32 bits */

/** The length of the FLAC signature in bytes. */
#define FLAC__STREAM_SYNC_LENGTH (4u)


/*****************************************************************************
 *
 * Subframe structures
 *
 *****************************************************************************/

/*****************************************************************************/

/** An enumeration of the available entropy coding methods. */
typedef enum {
	FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE = 0
	/**< Residual is coded by partitioning into contexts, each with it's own
	 * Rice parameter. */
} FLAC__EntropyCodingMethodType;

/** Maps a FLAC__EntropyCodingMethodType to a C string.
 *
 *  Using a FLAC__EntropyCodingMethodType as the index to this array will
 *  give the string equivalent.  The contents should not be modified.
 */
extern FLAC_API const char * const FLAC__EntropyCodingMethodTypeString[];


/** Contents of a Rice partitioned residual
 */
typedef struct {

	unsigned *parameters;
	/**< The Rice parameters for each context. */

	unsigned *raw_bits;
	/**< Widths for escape-coded partitions. */

	unsigned capacity_by_order;
	/**< The capacity of the \a parameters and \a raw_bits arrays
	 * specified as an order, i.e. the number of array elements
	 * allocated is 2 ^ \a capacity_by_order.
	 */
} FLAC__EntropyCodingMethod_PartitionedRiceContents;

/** Header for a Rice partitioned residual.  (c.f. <A HREF="../format.html#partitioned_rice">format specification</A>)
 */
typedef struct {

	unsigned order;
	/**< The partition order, i.e. # of contexts = 2 ^ \a order. */

	const FLAC__EntropyCodingMethod_PartitionedRiceContents *contents;
	/**< The context's Rice parameters and/or raw bits. */

} FLAC__EntropyCodingMethod_PartitionedRice;

extern FLAC_API const unsigned FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_ORDER_LEN; /**< == 4 (bits) */
extern FLAC_API const unsigned FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN; /**< == 4 (bits) */
extern FLAC_API const unsigned FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_RAW_LEN; /**< == 5 (bits) */

extern FLAC_API const unsigned FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_ESCAPE_PARAMETER;
/**< == (1<<FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN)-1 */

/** Header for the entropy coding method.  (c.f. <A HREF="../format.html#residual">format specification</A>)
 */
typedef struct {
	FLAC__EntropyCodingMethodType type;
	union {
		FLAC__EntropyCodingMethod_PartitionedRice partitioned_rice;
	} data;
} FLAC__EntropyCodingMethod;

extern FLAC_API const unsigned FLAC__ENTROPY_CODING_METHOD_TYPE_LEN; /**< == 2 (bits) */

/*****************************************************************************/

/** An enumeration of the available subframe types. */
typedef enum {
	FLAC__SUBFRAME_TYPE_CONSTANT = 0, /**< constant signal */
	FLAC__SUBFRAME_TYPE_VERBATIM = 1, /**< uncompressed signal */
	FLAC__SUBFRAME_TYPE_FIXED = 2, /**< fixed polynomial prediction */
	FLAC__SUBFRAME_TYPE_LPC = 3 /**< linear prediction */
} FLAC__SubframeType;

/** Maps a FLAC__SubframeType to a C string.
 *
 *  Using a FLAC__SubframeType as the index to this array will
 *  give the string equivalent.  The contents should not be modified.
 */
extern FLAC_API const char * const FLAC__SubframeTypeString[];


/** CONSTANT subframe.  (c.f. <A HREF="../format.html#subframe_constant">format specification</A>)
 */
typedef struct {
	FLAC__int32 value; /**< The constant signal value. */
} FLAC__Subframe_Constant;


/** VERBATIM subframe.  (c.f. <A HREF="../format.html#subframe_verbatim">format specification</A>)
 */
typedef struct {
	const FLAC__int32 *data; /**< A pointer to verbatim signal. */
} FLAC__Subframe_Verbatim;


/** FIXED subframe.  (c.f. <A HREF="../format.html#subframe_fixed">format specification</A>)
 */
typedef struct {
	FLAC__EntropyCodingMethod entropy_coding_method;
	/**< The residual coding method. */

	unsigned order;
	/**< The polynomial order. */

	FLAC__int32 warmup[FLAC__MAX_FIXED_ORDER];
	/**< Warmup samples to prime the predictor, length == order. */