xref: /external/flac/include/FLAC/stream_decoder.h

/* libFLAC - Free Lossless Audio Codec library
 * Copyright (C) 2000-2009  Josh Coalson
 * Copyright (C) 2011-2016  Xiph.Org Foundation
 *
 * 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__STREAM_DECODER_H
#define FLAC__STREAM_DECODER_H

#include <stdio.h> /* for FILE */
#include "export.h"
#include "format.h"

#ifdef __cplusplus
extern "C" {
#endif


/** \file include/FLAC/stream_decoder.h
 *
 *  \brief
 *  This module contains the functions which implement the stream
 *  decoder.
 *
 *  See the detailed documentation in the
 *  \link flac_stream_decoder stream decoder \endlink module.
 */

/** \defgroup flac_decoder FLAC/ \*_decoder.h: decoder interfaces
 *  \ingroup flac
 *
 *  \brief
 *  This module describes the decoder layers provided by libFLAC.
 *
 * The stream decoder can be used to decode complete streams either from
 * the client via callbacks, or directly from a file, depending on how
 * it is initialized.  When decoding via callbacks, the client provides
 * callbacks for reading FLAC data and writing decoded samples, and
 * handling metadata and errors.  If the client also supplies seek-related
 * callback, the decoder function for sample-accurate seeking within the
 * FLAC input is also available.  When decoding from a file, the client
 * needs only supply a filename or open \c FILE* and write/metadata/error
 * callbacks; the rest of the callbacks are supplied internally.  For more
 * info see the \link flac_stream_decoder stream decoder \endlink module.
 */

/** \defgroup flac_stream_decoder FLAC/stream_decoder.h: stream decoder interface
 *  \ingroup flac_decoder
 *
 *  \brief
 *  This module contains the functions which implement the stream
 *  decoder.
 *
 * The stream decoder can decode native FLAC, and optionally Ogg FLAC
 * (check FLAC_API_SUPPORTS_OGG_FLAC) streams and files.
 *
 * The basic usage of this decoder is as follows:
 * - The program creates an instance of a decoder using
 *   FLAC__stream_decoder_new().
 * - The program overrides the default settings using
 *   FLAC__stream_decoder_set_*() functions.
 * - The program initializes the instance to validate the settings and
 *   prepare for decoding using
 *   - FLAC__stream_decoder_init_stream() or FLAC__stream_decoder_init_FILE()
 *     or FLAC__stream_decoder_init_file() for native FLAC,
 *   - FLAC__stream_decoder_init_ogg_stream() or FLAC__stream_decoder_init_ogg_FILE()
 *     or FLAC__stream_decoder_init_ogg_file() for Ogg FLAC
 * - The program calls the FLAC__stream_decoder_process_*() functions
 *   to decode data, which subsequently calls the callbacks.
 * - The program finishes the decoding with FLAC__stream_decoder_finish(),
 *   which flushes the input and output and resets the decoder to the
 *   uninitialized state.
 * - The instance may be used again or deleted with
 *   FLAC__stream_decoder_delete().
 *
 * In more detail, the program will create a new instance by calling
 * FLAC__stream_decoder_new(), then call FLAC__stream_decoder_set_*()
 * functions to override the default decoder options, and call
 * one of the FLAC__stream_decoder_init_*() functions.
 *
 * There are three initialization functions for native FLAC, one for
 * setting up the decoder to decode FLAC data from the client via
 * callbacks, and two for decoding directly from a FLAC file.
 *
 * For decoding via callbacks, use FLAC__stream_decoder_init_stream().
 * You must also supply several callbacks for handling I/O.  Some (like
 * seeking) are optional, depending on the capabilities of the input.
 *
 * For decoding directly from a file, use FLAC__stream_decoder_init_FILE()
 * or FLAC__stream_decoder_init_file().  Then you must only supply an open
 * \c FILE* or filename and fewer callbacks; the decoder will handle
 * the other callbacks internally.
 *
 * There are three similarly-named init functions for decoding from Ogg
 * FLAC streams.  Check \c FLAC_API_SUPPORTS_OGG_FLAC to find out if the
 * library has been built with Ogg support.
 *
 * Once the decoder is initialized, your program will call one of several
 * functions to start the decoding process:
 *
 * - FLAC__stream_decoder_process_single() - Tells the decoder to process at
 *   most one metadata block or audio frame and return, calling either the
 *   metadata callback or write callback, respectively, once.  If the decoder
 *   loses sync it will return with only the error callback being called.
 * - FLAC__stream_decoder_process_until_end_of_metadata() - Tells the decoder
 *   to process the stream from the current location and stop upon reaching
 *   the first audio frame.  The client will get one metadata, write, or error
 *   callback per metadata block, audio frame, or sync error, respectively.
 * - FLAC__stream_decoder_process_until_end_of_stream() - Tells the decoder
 *   to process the stream from the current location until the read callback
 *   returns FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM or
 *   FLAC__STREAM_DECODER_READ_STATUS_ABORT.  The client will get one metadata,
 *   write, or error callback per metadata block, audio frame, or sync error,
 *   respectively.
 *
 * When the decoder has finished decoding (normally or through an abort),
 * the instance is finished by calling FLAC__stream_decoder_finish(), which
 * ensures the decoder is in the correct state and frees memory.  Then the
 * instance may be deleted with FLAC__stream_decoder_delete() or initialized
 * again to decode another stream.
 *
 * Seeking is exposed through the FLAC__stream_decoder_seek_absolute() method.
 * At any point after the stream decoder has been initialized, the client can
 * call this function to seek to an exact sample within the stream.
 * Subsequently, the first time the write callback is called it will be
 * passed a (possibly partial) block starting at that sample.
 *
 * If the client cannot seek via the callback interface provided, but still
 * has another way of seeking, it can flush the decoder using
 * FLAC__stream_decoder_flush() and start feeding data from the new position
 * through the read callback.
 *
 * The stream decoder also provides MD5 signature checking.  If this is
 * turned on before initialization, FLAC__stream_decoder_finish() will
 * report when the decoded MD5 signature does not match the one stored
 * in the STREAMINFO block.  MD5 checking is automatically turned off
 * (until the next FLAC__stream_decoder_reset()) if there is no signature
 * in the STREAMINFO block or when a seek is attempted.
 *
 * The FLAC__stream_decoder_set_metadata_*() functions deserve special
 * attention.  By default, the decoder only calls the metadata_callback for
 * the STREAMINFO block.  These functions allow you to tell the decoder
 * explicitly which blocks to parse and return via the metadata_callback
 * and/or which to skip.  Use a FLAC__stream_decoder_set_metadata_respond_all(),
 * FLAC__stream_decoder_set_metadata_ignore() ... or FLAC__stream_decoder_set_metadata_ignore_all(),
 * FLAC__stream_decoder_set_metadata_respond() ... sequence to exactly specify
 * which blocks to return.  Remember that metadata blocks can potentially
 * be big (for example, cover art) so filtering out the ones you don't
 * use can reduce the memory requirements of the decoder.  Also note the
 * special forms FLAC__stream_decoder_set_metadata_respond_application(id)
 * and FLAC__stream_decoder_set_metadata_ignore_application(id) for
 * filtering APPLICATION blocks based on the application ID.
 *
 * STREAMINFO and SEEKTABLE blocks are always parsed and used internally, but
 * they still can legally be filtered from the metadata_callback.
 *
 * \note
 * The "set" functions may only be called when the decoder is in the
 * state FLAC__STREAM_DECODER_UNINITIALIZED, i.e. after
 * FLAC__stream_decoder_new() or FLAC__stream_decoder_finish(), but
 * before FLAC__stream_decoder_init_*().  If this is the case they will
 * return \c true, otherwise \c false.
 *
 * \note
 * FLAC__stream_decoder_finish() resets all settings to the constructor
 * defaults, including the callbacks.
 *
 * \{
 */


/** State values for a FLAC__StreamDecoder
 *
 * The decoder's state can be obtained by calling FLAC__stream_decoder_get_state().
 */
typedef enum {

	FLAC__STREAM_DECODER_SEARCH_FOR_METADATA = 0,
	/**< The decoder is ready to search for metadata. */

	FLAC__STREAM_DECODER_READ_METADATA,
	/**< The decoder is ready to or is in the process of reading metadata. */

	FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC,
	/**< The decoder is ready to or is in the process of searching for the
	 * frame sync code.
	 */

	FLAC__STREAM_DECODER_READ_FRAME,
	/**< The decoder is ready to or is in the process of reading a frame. */

	FLAC__STREAM_DECODER_END_OF_STREAM,
	/**< The decoder has reached the end of the stream. */

	FLAC__STREAM_DECODER_OGG_ERROR,
	/**< An error occurred in the underlying Ogg layer.  */

	FLAC__STREAM_DECODER_SEEK_ERROR,
	/**< An error occurred while seeking.  The decoder must be flushed
	 * with FLAC__stream_decoder_flush() or reset with
	 * FLAC__stream_decoder_reset() before decoding can continue.
	 */

	FLAC__STREAM_DECODER_ABORTED,
	/**< The decoder was aborted by the read or write callback. */

	FLAC__STREAM_DECODER_MEMORY_ALLOCATION_ERROR,
	/**< An error occurred allocating memory.  The decoder is in an invalid
	 * state and can no longer be used.
	 */

	FLAC__STREAM_DECODER_UNINITIALIZED
	/**< The decoder is in the uninitialized state; one of the
	 * FLAC__stream_decoder_init_*() functions must be called before samples
	 * can be processed.
	 */

} FLAC__StreamDecoderState;

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


/** Possible return values for the FLAC__stream_decoder_init_*() functions.
 */
typedef enum {

	FLAC__STREAM_DECODER_INIT_STATUS_OK = 0,
	/**< Initialization was successful. */

	FLAC__STREAM_DECODER_INIT_STATUS_UNSUPPORTED_CONTAINER,
	/**< The library was not compiled with support for the given container
	 * format.
	 */

	FLAC__STREAM_DECODER_INIT_STATUS_INVALID_CALLBACKS,
	/**< A required callback was not supplied. */

	FLAC__STREAM_DECODER_INIT_STATUS_MEMORY_ALLOCATION_ERROR,
	/**< An error occurred allocating memory. */

	FLAC__STREAM_DECODER_INIT_STATUS_ERROR_OPENING_FILE,
	/**< fopen() failed in FLAC__stream_decoder_init_file() or
	 * FLAC__stream_decoder_init_ogg_file(). */

	FLAC__STREAM_DECODER_INIT_STATUS_ALREADY_INITIALIZED
	/**< FLAC__stream_decoder_init_*() was called when the decoder was
	 * already initialized, usually because
	 * FLAC__stream_decoder_finish() was not called.
	 */

} FLAC__StreamDecoderInitStatus;

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


/** Return values for the FLAC__StreamDecoder read callback.
 */
typedef enum {

	FLAC__STREAM_DECODER_READ_STATUS_CONTINUE,
	/**< The read was OK and decoding can continue. */

	FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM,
	/**< The read was attempted while at the end of the stream.  Note that
	 * the client must only return this value when the read callback was
	 * called when already at the end of the stream.  Otherwise, if the read
	 * itself moves to the end of the stream, the client should still return
	 * the data and \c FLAC__STREAM_DECODER_READ_STATUS_CONTINUE, and then on
	 * the next read callback it should return
	 * \c FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM with a byte count
	 * of \c 0.
	 */

	FLAC__STREAM_DECODER_READ_STATUS_ABORT
	/**< An unrecoverable error occurred.  The decoder will return from the process call. */

} FLAC__StreamDecoderReadStatus;

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


/** Return values for the FLAC__StreamDecoder seek callback.
 */
typedef enum {

	FLAC__STREAM_DECODER_SEEK_STATUS_OK,
	/**< The seek was OK and decoding can continue. */

	FLAC__STREAM_DECODER_SEEK_STATUS_ERROR,
	/**< An unrecoverable error occurred.  The decoder will return from the process call. */

	FLAC__STREAM_DECODER_SEEK_STATUS_UNSUPPORTED
	/**< Client does not support seeking. */

} FLAC__StreamDecoderSeekStatus;

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


/** Return values for the FLAC__StreamDecoder tell callback.
 */
typedef enum {

	FLAC__STREAM_DECODER_TELL_STATUS_OK,
	/**< The tell was OK and decoding can continue. */

	FLAC__STREAM_DECODER_TELL_STATUS_ERROR,
	/**< An unrecoverable error occurred.  The decoder will return from the process call. */

	FLAC__STREAM_DECODER_TELL_STATUS_UNSUPPORTED
	/**< Client does not support telling the position. */

} FLAC__StreamDecoderTellStatus;

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


/** Return values for the FLAC__StreamDecoder length callback.
 */
typedef enum {

	FLAC__STREAM_DECODER_LENGTH_STATUS_OK,
	/**< The length call was OK and decoding can continue. */

	FLAC__STREAM_DECODER_LENGTH_STATUS_ERROR,
	/**< An unrecoverable error occurred.  The decoder will return from the process call. */

	FLAC__STREAM_DECODER_LENGTH_STATUS_UNSUPPORTED
	/**< Client does not support reporting the length. */

} FLAC__StreamDecoderLengthStatus;

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


/** Return values for the FLAC__StreamDecoder write callback.
 */
typedef enum {

	FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE,
	/**< The write was OK and decoding can continue. */

	FLAC__STREAM_DECODER_WRITE_STATUS_ABORT
	/**< An unrecoverable error occurred.  The decoder will return from the process call. */

} FLAC__StreamDecoderWriteStatus;

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


/** Possible values passed back to the FLAC__StreamDecoder error callback.
 *  \c FLAC__STREAM_DECODER_ERROR_STATUS_LOST_SYNC is the generic catch-
 *  all.  The rest could be caused by bad sync (false synchronization on
 *  data that is not the start of a frame) or corrupted data.  The error
 *  itself is the decoder's best guess at what happened assuming a correct
 *  sync.  For example \c FLAC__STREAM_DECODER_ERROR_STATUS_BAD_HEADER
 *  could be caused by a correct sync on the start of a frame, but some
 *  data in the frame header was corrupted.  Or it could be the result of
 *  syncing on a point the stream that looked like the starting of a frame
 *  but was not.  \c FLAC__STREAM_DECODER_ERROR_STATUS_UNPARSEABLE_STREAM
 *  could be because the decoder encountered a valid frame made by a future
 *  version of the encoder which it cannot parse, or because of a false
 *  sync making it appear as though an encountered frame was generated by
 *  a future encoder.
 */
typedef enum {

	FLAC__STREAM_DECODER_ERROR_STATUS_LOST_SYNC,
	/**< An error in the stream caused the decoder to lose synchronization. */

	FLAC__STREAM_DECODER_ERROR_STATUS_BAD_HEADER,
	/**< The decoder encountered a corrupted frame header. */

	FLAC__STREAM_DECODER_ERROR_STATUS_FRAME_CRC_MISMATCH,
	/**< The frame's data did not match the CRC in the footer. */

	FLAC__STREAM_DECODER_ERROR_STATUS_UNPARSEABLE_STREAM
	/**< The decoder encountered reserved fields in use in the stream. */

} FLAC__StreamDecoderErrorStatus;

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


/***********************************************************************
 *
 * class FLAC__StreamDecoder
 *
 ***********************************************************************/

struct FLAC__StreamDecoderProtected;
struct FLAC__StreamDecoderPrivate;
/** The opaque structure definition for the stream decoder type.
 *  See the \link flac_stream_decoder stream decoder module \endlink
 *  for a detailed description.
 */
typedef struct {
	struct FLAC__StreamDecoderProtected *protected_; /* avoid the C++ keyword 'protected' */
	struct FLAC__StreamDecoderPrivate *private_; /* avoid the C++ keyword 'private' */
} FLAC__StreamDecoder;

/** Signature for the read callback.
 *
 *  A function pointer matching this signature must be passed to
 *  FLAC__stream_decoder_init*_stream(). The supplied function will be
 *  called when the decoder needs more input data.  The address of the
 *  buffer to be filled is supplied, along with the number of bytes the
 *  buffer can hold.  The callback may choose to supply less data and
 *  modify the byte count but must be careful not to overflow the buffer.
 *  The callback then returns a status code chosen from
 *  FLAC__StreamDecoderReadStatus.
 *
 * Here is an example of a read callback for stdio streams:
 * \code
 * FLAC__StreamDecoderReadStatus read_cb(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], size_t *bytes, void *client_data)
 * {
 *   FILE *file = ((MyClientData*)client_data)->file;
 *   if(*bytes > 0) {
 *     *bytes = fread(buffer, sizeof(FLAC__byte), *bytes, file);
 *     if(ferror(file))
 *       return FLAC__STREAM_DECODER_READ_STATUS_ABORT;
 *     else if(*bytes == 0)
 *       return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
 *     else
 *       return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
 *   }
 *   else
 *     return FLAC__STREAM_DECODER_READ_STATUS_ABORT;
 * }
 * \endcode
 *
 * \note In general, FLAC__StreamDecoder functions which change the
 * state should not be called on the \a decoder while in the callback.
 *
 * \param  decoder  The decoder instance calling the callback.
 * \param  buffer   A pointer to a location for the callee to store
 *                  data to be decoded.
 * \param  bytes    A pointer to the size of the buffer.  On entry
 *                  to the callback, it contains the maximum number
 *                  of bytes that may be stored in \a buffer.  The
 *                  callee must set it to the actual number of bytes
 *                  stored (0 in case of error or end-of-stream) before
 *                  returning.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_decoder_init_*().
 * \retval FLAC__StreamDecoderReadStatus
 *    The callee's return status.  Note that the callback should return
 *    \c FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM if and only if
 *    zero bytes were read and there is no more data to be read.
 */
typedef FLAC__StreamDecoderReadStatus (*FLAC__StreamDecoderReadCallback)(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], size_t *bytes, void *client_data);

/** Signature for the seek callback.
 *
 *  A function pointer matching this signature may be passed to
 *  FLAC__stream_decoder_init*_stream().  The supplied function will be
 *  called when the decoder needs to seek the input stream.  The decoder
 *  will pass the absolute byte offset to seek to, 0 meaning the
 *  beginning of the stream.
 *
 * Here is an example of a seek callback for stdio streams:
 * \code
 * FLAC__StreamDecoderSeekStatus seek_cb(const FLAC__StreamDecoder *decoder, FLAC__uint64 absolute_byte_offset, void *client_data)
 * {
 *   FILE *file = ((MyClientData*)client_data)->file;
 *   if(file == stdin)
 *     return FLAC__STREAM_DECODER_SEEK_STATUS_UNSUPPORTED;
 *   else if(fseeko(file, (off_t)absolute_byte_offset, SEEK_SET) < 0)
 *     return FLAC__STREAM_DECODER_SEEK_STATUS_ERROR;
 *   else
 *     return FLAC__STREAM_DECODER_SEEK_STATUS_OK;
 * }
 * \endcode
 *
 * \note In general, FLAC__StreamDecoder functions which change the
 * state should not be called on the \a decoder while in the callback.
 *
 * \param  decoder  The decoder instance calling the callback.
 * \param  absolute_byte_offset  The offset from the beginning of the stream
 *                               to seek to.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_decoder_init_*().
 * \retval FLAC__StreamDecoderSeekStatus
 *    The callee's return status.
 */
typedef FLAC__StreamDecoderSeekStatus (*FLAC__StreamDecoderSeekCallback)(const FLAC__StreamDecoder *decoder, FLAC__uint64 absolute_byte_offset, void *client_data);

/** Signature for the tell callback.
 *
 *  A function pointer matching this signature may be passed to
 *  FLAC__stream_decoder_init*_stream().  The supplied function will be
 *  called when the decoder wants to know the current position of the
 *  stream.  The callback should return the byte offset from the
 *  beginning of the stream.
 *
 * Here is an example of a tell callback for stdio streams:
 * \code
 * FLAC__StreamDecoderTellStatus tell_cb(const FLAC__StreamDecoder *decoder, FLAC__uint64 *absolute_byte_offset, void *client_data)
 * {
 *   FILE *file = ((MyClientData*)client_data)->file;
 *   off_t pos;
 *   if(file == stdin)
 *     return FLAC__STREAM_DECODER_TELL_STATUS_UNSUPPORTED;
 *   else if((pos = ftello(file)) < 0)
 *     return FLAC__STREAM_DECODER_TELL_STATUS_ERROR;
 *   else {
 *     *absolute_byte_offset = (FLAC__uint64)pos;
 *     return FLAC__STREAM_DECODER_TELL_STATUS_OK;
 *   }
 * }
 * \endcode
 *
 * \note In general, FLAC__StreamDecoder functions which change the
 * state should not be called on the \a decoder while in the callback.
 *
 * \param  decoder  The decoder instance calling the callback.
 * \param  absolute_byte_offset  A pointer to storage for the current offset
 *                               from the beginning of the stream.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_decoder_init_*().
 * \retval FLAC__StreamDecoderTellStatus
 *    The callee's return status.
 */
typedef FLAC__StreamDecoderTellStatus (*FLAC__StreamDecoderTellCallback)(const FLAC__StreamDecoder *decoder, FLAC__uint64 *absolute_byte_offset, void *client_data);

/** Signature for the length callback.
 *
 *  A function pointer matching this signature may be passed to
 *  FLAC__stream_decoder_init*_stream().  The supplied function will be
 *  called when the decoder wants to know the total length of the stream
 *  in bytes.
 *
 * Here is an example of a length callback for stdio streams:
 * \code
 * FLAC__StreamDecoderLengthStatus length_cb(const FLAC__StreamDecoder *decoder, FLAC__uint64 *stream_length, void *client_data)
 * {
 *   FILE *file = ((MyClientData*)client_data)->file;
 *   struct stat filestats;
 *
 *   if(file == stdin)
 *     return FLAC__STREAM_DECODER_LENGTH_STATUS_UNSUPPORTED;
 *   else if(fstat(fileno(file), &filestats) != 0)
 *     return FLAC__STREAM_DECODER_LENGTH_STATUS_ERROR;
 *   else {
 *     *stream_length = (FLAC__uint64)filestats.st_size;
 *     return FLAC__STREAM_DECODER_LENGTH_STATUS_OK;
 *   }
 * }
 * \endcode
 *
 * \note In general, FLAC__StreamDecoder functions which change the
 * state should not be called on the \a decoder while in the callback.
 *
 * \param  decoder  The decoder instance calling the callback.
 * \param  stream_length  A pointer to storage for the length of the stream
 *                        in bytes.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_decoder_init_*().
 * \retval FLAC__StreamDecoderLengthStatus
 *    The callee's return status.
 */
typedef FLAC__StreamDecoderLengthStatus (*FLAC__StreamDecoderLengthCallback)(const FLAC__StreamDecoder *decoder, FLAC__uint64 *stream_length, void *client_data);

/** Signature for the EOF callback.
 *
 *  A function pointer matching this signature may be passed to
 *  FLAC__stream_decoder_init*_stream().  The supplied function will be
 *  called when the decoder needs to know if the end of the stream has
 *  been reached.
 *
 * Here is an example of a EOF callback for stdio streams:
 * FLAC__bool eof_cb(const FLAC__StreamDecoder *decoder, void *client_data)
 * \code
 * {
 *   FILE *file = ((MyClientData*)client_data)->file;
 *   return feof(file)? true : false;
 * }
 * \endcode
 *
 * \note In general, FLAC__StreamDecoder functions which change the
 * state should not be called on the \a decoder while in the callback.
 *
 * \param  decoder  The decoder instance calling the callback.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_decoder_init_*().
 * \retval FLAC__bool
 *    \c true if the currently at the end of the stream, else \c false.
 */
typedef FLAC__bool (*FLAC__StreamDecoderEofCallback)(const FLAC__StreamDecoder *decoder, void *client_data);

/** Signature for the write callback.
 *
 *  A function pointer matching this signature must be passed to one of
 *  the FLAC__stream_decoder_init_*() functions.
 *  The supplied function will be called when the decoder has decoded a
 *  single audio frame.  The decoder will pass the frame metadata as well
 *  as an array of pointers (one for each channel) pointing to the
 *  decoded audio.
 *
 * \note In general, FLAC__StreamDecoder functions which change the
 * state should not be called on the \a decoder while in the callback.
 *
 * \param  decoder  The decoder instance calling the callback.
 * \param  frame    The description of the decoded frame.  See
 *                  FLAC__Frame.
 * \param  buffer   An array of pointers to decoded channels of data.
 *                  Each pointer will point to an array of signed
 *                  samples of length \a frame->header.blocksize.
 *                  Channels will be ordered according to the FLAC
 *                  specification; see the documentation for the
 *                  <A HREF="../format.html#frame_header">frame header</A>.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_decoder_init_*().
 * \retval FLAC__StreamDecoderWriteStatus
 *    The callee's return status.
 */
typedef FLAC__StreamDecoderWriteStatus (*FLAC__StreamDecoderWriteCallback)(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data);

/** Signature for the metadata callback.
 *
 *  A function pointer matching this signature must be passed to one of
 *  the FLAC__stream_decoder_init_*() functions.
 *  The supplied function will be called when the decoder has decoded a
 *  metadata block.  In a valid FLAC file there will always be one
 *  \c STREAMINFO block, followed by zero or more other metadata blocks.
 *  These will be supplied by the decoder in the same order as they
 *  appear in the stream and always before the first audio frame (i.e.
 *  write callback).  The metadata block that is passed in must not be
 *  modified, and it doesn't live beyond the callback, so you should make
 *  a copy of it with FLAC__metadata_object_clone() if you will need it
 *  elsewhere.  Since metadata blocks can potentially be large, by
 *  default the decoder only calls the metadata callback for the
 *  \c STREAMINFO block; you can instruct the decoder to pass or filter
 *  other blocks with FLAC__stream_decoder_set_metadata_*() calls.
 *
 * \note In general, FLAC__StreamDecoder functions which change the
 * state should not be called on the \a decoder while in the callback.
 *
 * \param  decoder  The decoder instance calling the callback.
 * \param  metadata The decoded metadata block.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_decoder_init_*().
 */
typedef void (*FLAC__StreamDecoderMetadataCallback)(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data);

/** Signature for the error callback.
 *
 *  A function pointer matching this signature must be passed to one of
 *  the FLAC__stream_decoder_init_*() functions.
 *  The supplied function will be called whenever an error occurs during
 *  decoding.
 *
 * \note In general, FLAC__StreamDecoder functions which change the
 * state should not be called on the \a decoder while in the callback.
 *
 * \param  decoder  The decoder instance calling the callback.
 * \param  status   The error encountered by the decoder.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_decoder_init_*().
 */
typedef void (*FLAC__StreamDecoderErrorCallback)(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data);


/***********************************************************************
 *
 * Class constructor/destructor
 *
 ***********************************************************************/

/** Create a new stream decoder instance.  The instance is created with
 *  default settings; see the individual FLAC__stream_decoder_set_*()
 *  functions for each setting's default.
 *
 * \retval FLAC__StreamDecoder*
 *    \c NULL if there was an error allocating memory, else the new instance.
 */
FLAC_API FLAC__StreamDecoder *FLAC__stream_decoder_new(void);

/** Free a decoder instance.  Deletes the object pointed to by \a decoder.
 *
 * \param decoder  A pointer to an existing decoder.
 * \assert
 *    \code decoder != NULL \endcode
 */
FLAC_API void FLAC__stream_decoder_delete(FLAC__StreamDecoder *decoder);


/***********************************************************************
 *
 * Public class method prototypes
 *
 ***********************************************************************/

/** Set the serial number for the FLAC stream within the Ogg container.
 *  The default behavior is to use the serial number of the first Ogg
 *  page.  Setting a serial number here will explicitly specify which
 *  stream is to be decoded.
 *
 * \note
 * This does not need to be set for native FLAC decoding.
 *
 * \default \c use serial number of first page
 * \param  decoder        A decoder instance to set.
 * \param  serial_number  See above.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c false if the decoder is already initialized, else \c true.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_set_ogg_serial_number(FLAC__StreamDecoder *decoder, long serial_number);

/** Set the "MD5 signature checking" flag.  If \c true, the decoder will
 *  compute the MD5 signature of the unencoded audio data while decoding
 *  and compare it to the signature from the STREAMINFO block, if it
 *  exists, during FLAC__stream_decoder_finish().
 *
 *  MD5 signature checking will be turned off (until the next
 *  FLAC__stream_decoder_reset()) if there is no signature in the
 *  STREAMINFO block or when a seek is attempted.
 *
 *  Clients that do not use the MD5 check should leave this off to speed
 *  up decoding.
 *
 * \default \c false
 * \param  decoder  A decoder instance to set.
 * \param  value    Flag value (see above).
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c false if the decoder is already initialized, else \c true.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_set_md5_checking(FLAC__StreamDecoder *decoder, FLAC__bool value);

/** Direct the decoder to pass on all metadata blocks of type \a type.
 *
 * \default By default, only the \c STREAMINFO block is returned via the
 *          metadata callback.
 * \param  decoder  A decoder instance to set.
 * \param  type     See above.
 * \assert
 *    \code decoder != NULL \endcode
 *    \a type is valid
 * \retval FLAC__bool
 *    \c false if the decoder is already initialized, else \c true.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_set_metadata_respond(FLAC__StreamDecoder *decoder, FLAC__MetadataType type);

/** Direct the decoder to pass on all APPLICATION metadata blocks of the
 *  given \a id.
 *
 * \default By default, only the \c STREAMINFO block is returned via the
 *          metadata callback.
 * \param  decoder  A decoder instance to set.
 * \param  id       See above.
 * \assert
 *    \code decoder != NULL \endcode
 *    \code id != NULL \endcode
 * \retval FLAC__bool
 *    \c false if the decoder is already initialized, else \c true.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_set_metadata_respond_application(FLAC__StreamDecoder *decoder, const FLAC__byte id[4]);

/** Direct the decoder to pass on all metadata blocks of any type.
 *
 * \default By default, only the \c STREAMINFO block is returned via the
 *          metadata callback.
 * \param  decoder  A decoder instance to set.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c false if the decoder is already initialized, else \c true.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_set_metadata_respond_all(FLAC__StreamDecoder *decoder);

/** Direct the decoder to filter out all metadata blocks of type \a type.
 *
 * \default By default, only the \c STREAMINFO block is returned via the
 *          metadata callback.
 * \param  decoder  A decoder instance to set.
 * \param  type     See above.
 * \assert
 *    \code decoder != NULL \endcode
 *    \a type is valid
 * \retval FLAC__bool
 *    \c false if the decoder is already initialized, else \c true.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_set_metadata_ignore(FLAC__StreamDecoder *decoder, FLAC__MetadataType type);

/** Direct the decoder to filter out all APPLICATION metadata blocks of
 *  the given \a id.
 *
 * \default By default, only the \c STREAMINFO block is returned via the
 *          metadata callback.
 * \param  decoder  A decoder instance to set.
 * \param  id       See above.
 * \assert
 *    \code decoder != NULL \endcode
 *    \code id != NULL \endcode
 * \retval FLAC__bool
 *    \c false if the decoder is already initialized, else \c true.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_set_metadata_ignore_application(FLAC__StreamDecoder *decoder, const FLAC__byte id[4]);

/** Direct the decoder to filter out all metadata blocks of any type.
 *
 * \default By default, only the \c STREAMINFO block is returned via the
 *          metadata callback.
 * \param  decoder  A decoder instance to set.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c false if the decoder is already initialized, else \c true.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_set_metadata_ignore_all(FLAC__StreamDecoder *decoder);

/** Get the current decoder state.
 *
 * \param  decoder  A decoder instance to query.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__StreamDecoderState
 *    The current decoder state.
 */
FLAC_API FLAC__StreamDecoderState FLAC__stream_decoder_get_state(const FLAC__StreamDecoder *decoder);

/** Get the current decoder state as a C string.
 *
 * \param  decoder  A decoder instance to query.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval const char *
 *    The decoder state as a C string.  Do not modify the contents.
 */
FLAC_API const char *FLAC__stream_decoder_get_resolved_state_string(const FLAC__StreamDecoder *decoder);

/** Get the "MD5 signature checking" flag.
 *  This is the value of the setting, not whether or not the decoder is
 *  currently checking the MD5 (remember, it can be turned off automatically
 *  by a seek).  When the decoder is reset the flag will be restored to the
 *  value returned by this function.
 *
 * \param  decoder  A decoder instance to query.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    See above.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_get_md5_checking(const FLAC__StreamDecoder *decoder);

/** Get the total number of samples in the stream being decoded.
 *  Will only be valid after decoding has started and will contain the
 *  value from the \c STREAMINFO block.  A value of \c 0 means "unknown".
 *
 * \param  decoder  A decoder instance to query.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval unsigned
 *    See above.
 */
FLAC_API FLAC__uint64 FLAC__stream_decoder_get_total_samples(const FLAC__StreamDecoder *decoder);

/** Get the current number of channels in the stream being decoded.
 *  Will only be valid after decoding has started and will contain the
 *  value from the most recently decoded frame header.
 *
 * \param  decoder  A decoder instance to query.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval unsigned
 *    See above.
 */
FLAC_API unsigned FLAC__stream_decoder_get_channels(const FLAC__StreamDecoder *decoder);

/** Get the current channel assignment in the stream being decoded.
 *  Will only be valid after decoding has started and will contain the
 *  value from the most recently decoded frame header.
 *
 * \param  decoder  A decoder instance to query.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__ChannelAssignment
 *    See above.
 */
FLAC_API FLAC__ChannelAssignment FLAC__stream_decoder_get_channel_assignment(const FLAC__StreamDecoder *decoder);

/** Get the current sample resolution in the stream being decoded.
 *  Will only be valid after decoding has started and will contain the
 *  value from the most recently decoded frame header.
 *
 * \param  decoder  A decoder instance to query.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval unsigned
 *    See above.
 */
FLAC_API unsigned FLAC__stream_decoder_get_bits_per_sample(const FLAC__StreamDecoder *decoder);

/** Get the current sample rate in Hz of the stream being decoded.
 *  Will only be valid after decoding has started and will contain the
 *  value from the most recently decoded frame header.
 *
 * \param  decoder  A decoder instance to query.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval unsigned
 *    See above.
 */
FLAC_API unsigned FLAC__stream_decoder_get_sample_rate(const FLAC__StreamDecoder *decoder);

/** Get the current blocksize of the stream being decoded.
 *  Will only be valid after decoding has started and will contain the
 *  value from the most recently decoded frame header.
 *
 * \param  decoder  A decoder instance to query.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval unsigned
 *    See above.
 */
FLAC_API unsigned FLAC__stream_decoder_get_blocksize(const FLAC__StreamDecoder *decoder);

/** Returns the decoder's current read position within the stream.
 *  The position is the byte offset from the start of the stream.
 *  Bytes before this position have been fully decoded.  Note that
 *  there may still be undecoded bytes in the decoder's read FIFO.
 *  The returned position is correct even after a seek.
 *
 *  \warning This function currently only works for native FLAC,
 *           not Ogg FLAC streams.
 *
 * \param  decoder   A decoder instance to query.
 * \param  position  Address at which to return the desired position.
 * \assert
 *    \code decoder != NULL \endcode
 *    \code position != NULL \endcode
 * \retval FLAC__bool
 *    \c true if successful, \c false if the stream is not native FLAC,
 *    or there was an error from the 'tell' callback or it returned
 *    \c FLAC__STREAM_DECODER_TELL_STATUS_UNSUPPORTED.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_get_decode_position(const FLAC__StreamDecoder *decoder, FLAC__uint64 *position);

/** Initialize the decoder instance to decode native FLAC streams.
 *
 *  This flavor of initialization sets up the decoder to decode from a
 *  native FLAC stream. I/O is performed via callbacks to the client.
 *  For decoding from a plain file via filename or open FILE*,
 *  FLAC__stream_decoder_init_file() and FLAC__stream_decoder_init_FILE()
 *  provide a simpler interface.
 *
 *  This function should be called after FLAC__stream_decoder_new() and
 *  FLAC__stream_decoder_set_*() but before any of the
 *  FLAC__stream_decoder_process_*() functions.  Will set and return the
 *  decoder state, which will be FLAC__STREAM_DECODER_SEARCH_FOR_METADATA
 *  if initialization succeeded.
 *
 * \param  decoder            An uninitialized decoder instance.
 * \param  read_callback      See FLAC__StreamDecoderReadCallback.  This
 *                            pointer must not be \c NULL.
 * \param  seek_callback      See FLAC__StreamDecoderSeekCallback.  This
 *                            pointer may be \c NULL if seeking is not
 *                            supported.  If \a seek_callback is not \c NULL then a
 *                            \a tell_callback, \a length_callback, and \a eof_callback must also be supplied.
 *                            Alternatively, a dummy seek callback that just
 *                            returns \c FLAC__STREAM_DECODER_SEEK_STATUS_UNSUPPORTED
 *                            may also be supplied, all though this is slightly
 *                            less efficient for the decoder.
 * \param  tell_callback      See FLAC__StreamDecoderTellCallback.  This
 *                            pointer may be \c NULL if not supported by the client.  If
 *                            \a seek_callback is not \c NULL then a
 *                            \a tell_callback must also be supplied.
 *                            Alternatively, a dummy tell callback that just
 *                            returns \c FLAC__STREAM_DECODER_TELL_STATUS_UNSUPPORTED
 *                            may also be supplied, all though this is slightly
 *                            less efficient for the decoder.
 * \param  length_callback    See FLAC__StreamDecoderLengthCallback.  This
 *                            pointer may be \c NULL if not supported by the client.  If
 *                            \a seek_callback is not \c NULL then a
 *                            \a length_callback must also be supplied.
 *                            Alternatively, a dummy length callback that just
 *                            returns \c FLAC__STREAM_DECODER_LENGTH_STATUS_UNSUPPORTED
 *                            may also be supplied, all though this is slightly
 *                            less efficient for the decoder.
 * \param  eof_callback       See FLAC__StreamDecoderEofCallback.  This
 *                            pointer may be \c NULL if not supported by the client.  If
 *                            \a seek_callback is not \c NULL then a
 *                            \a eof_callback must also be supplied.
 *                            Alternatively, a dummy length callback that just
 *                            returns \c false
 *                            may also be supplied, all though this is slightly
 *                            less efficient for the decoder.
 * \param  write_callback     See FLAC__StreamDecoderWriteCallback.  This
 *                            pointer must not be \c NULL.
 * \param  metadata_callback  See FLAC__StreamDecoderMetadataCallback.  This
 *                            pointer may be \c NULL if the callback is not
 *                            desired.
 * \param  error_callback     See FLAC__StreamDecoderErrorCallback.  This
 *                            pointer must not be \c NULL.
 * \param  client_data        This value will be supplied to callbacks in their
 *                            \a client_data argument.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__StreamDecoderInitStatus
 *    \c FLAC__STREAM_DECODER_INIT_STATUS_OK if initialization was successful;
 *    see FLAC__StreamDecoderInitStatus for the meanings of other return values.
 */
FLAC_API FLAC__StreamDecoderInitStatus FLAC__stream_decoder_init_stream(
	FLAC__StreamDecoder *decoder,
	FLAC__StreamDecoderReadCallback read_callback,
	FLAC__StreamDecoderSeekCallback seek_callback,
	FLAC__StreamDecoderTellCallback tell_callback,
	FLAC__StreamDecoderLengthCallback length_callback,
	FLAC__StreamDecoderEofCallback eof_callback,
	FLAC__StreamDecoderWriteCallback write_callback,
	FLAC__StreamDecoderMetadataCallback metadata_callback,
	FLAC__StreamDecoderErrorCallback error_callback,
	void *client_data
);

/** Initialize the decoder instance to decode Ogg FLAC streams.
 *
 *  This flavor of initialization sets up the decoder to decode from a
 *  FLAC stream in an Ogg container. I/O is performed via callbacks to the
 *  client.  For decoding from a plain file via filename or open FILE*,
 *  FLAC__stream_decoder_init_ogg_file() and FLAC__stream_decoder_init_ogg_FILE()
 *  provide a simpler interface.
 *
 *  This function should be called after FLAC__stream_decoder_new() and
 *  FLAC__stream_decoder_set_*() but before any of the
 *  FLAC__stream_decoder_process_*() functions.  Will set and return the
 *  decoder state, which will be FLAC__STREAM_DECODER_SEARCH_FOR_METADATA
 *  if initialization succeeded.
 *
 *  \note Support for Ogg FLAC in the library is optional.  If this
 *  library has been built without support for Ogg FLAC, this function
 *  will return \c FLAC__STREAM_DECODER_INIT_STATUS_UNSUPPORTED_CONTAINER.
 *
 * \param  decoder            An uninitialized decoder instance.
 * \param  read_callback      See FLAC__StreamDecoderReadCallback.  This
 *                            pointer must not be \c NULL.
 * \param  seek_callback      See FLAC__StreamDecoderSeekCallback.  This
 *                            pointer may be \c NULL if seeking is not
 *                            supported.  If \a seek_callback is not \c NULL then a
 *                            \a tell_callback, \a length_callback, and \a eof_callback must also be supplied.
 *                            Alternatively, a dummy seek callback that just
 *                            returns \c FLAC__STREAM_DECODER_SEEK_STATUS_UNSUPPORTED
 *                            may also be supplied, all though this is slightly
 *                            less efficient for the decoder.
 * \param  tell_callback      See FLAC__StreamDecoderTellCallback.  This
 *                            pointer may be \c NULL if not supported by the client.  If
 *                            \a seek_callback is not \c NULL then a
 *                            \a tell_callback must also be supplied.
 *                            Alternatively, a dummy tell callback that just
 *                            returns \c FLAC__STREAM_DECODER_TELL_STATUS_UNSUPPORTED
 *                            may also be supplied, all though this is slightly
 *                            less efficient for the decoder.
 * \param  length_callback    See FLAC__StreamDecoderLengthCallback.  This
 *                            pointer may be \c NULL if not supported by the client.  If
 *                            \a seek_callback is not \c NULL then a
 *                            \a length_callback must also be supplied.
 *                            Alternatively, a dummy length callback that just
 *                            returns \c FLAC__STREAM_DECODER_LENGTH_STATUS_UNSUPPORTED
 *                            may also be supplied, all though this is slightly
 *                            less efficient for the decoder.
 * \param  eof_callback       See FLAC__StreamDecoderEofCallback.  This
 *                            pointer may be \c NULL if not supported by the client.  If
 *                            \a seek_callback is not \c NULL then a
 *                            \a eof_callback must also be supplied.
 *                            Alternatively, a dummy length callback that just
 *                            returns \c false
 *                            may also be supplied, all though this is slightly
 *                            less efficient for the decoder.
 * \param  write_callback     See FLAC__StreamDecoderWriteCallback.  This
 *                            pointer must not be \c NULL.
 * \param  metadata_callback  See FLAC__StreamDecoderMetadataCallback.  This
 *                            pointer may be \c NULL if the callback is not
 *                            desired.
 * \param  error_callback     See FLAC__StreamDecoderErrorCallback.  This
 *                            pointer must not be \c NULL.
 * \param  client_data        This value will be supplied to callbacks in their
 *                            \a client_data argument.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__StreamDecoderInitStatus
 *    \c FLAC__STREAM_DECODER_INIT_STATUS_OK if initialization was successful;
 *    see FLAC__StreamDecoderInitStatus for the meanings of other return values.
 */
FLAC_API FLAC__StreamDecoderInitStatus FLAC__stream_decoder_init_ogg_stream(
	FLAC__StreamDecoder *decoder,
	FLAC__StreamDecoderReadCallback read_callback,
	FLAC__StreamDecoderSeekCallback seek_callback,
	FLAC__StreamDecoderTellCallback tell_callback,
	FLAC__StreamDecoderLengthCallback length_callback,
	FLAC__StreamDecoderEofCallback eof_callback,
	FLAC__StreamDecoderWriteCallback write_callback,
	FLAC__StreamDecoderMetadataCallback metadata_callback,
	FLAC__StreamDecoderErrorCallback error_callback,
	void *client_data
);

/** Initialize the decoder instance to decode native FLAC files.
 *
 *  This flavor of initialization sets up the decoder to decode from a
 *  plain native FLAC file.  For non-stdio streams, you must use
 *  FLAC__stream_decoder_init_stream() and provide callbacks for the I/O.
 *
 *  This function should be called after FLAC__stream_decoder_new() and
 *  FLAC__stream_decoder_set_*() but before any of the
 *  FLAC__stream_decoder_process_*() functions.  Will set and return the
 *  decoder state, which will be FLAC__STREAM_DECODER_SEARCH_FOR_METADATA
 *  if initialization succeeded.
 *
 * \param  decoder            An uninitialized decoder instance.
 * \param  file               An open FLAC file.  The file should have been
 *                            opened with mode \c "rb" and rewound.  The file
 *                            becomes owned by the decoder and should not be
 *                            manipulated by the client while decoding.
 *                            Unless \a file is \c stdin, it will be closed
 *                            when FLAC__stream_decoder_finish() is called.
 *                            Note however that seeking will not work when
 *                            decoding from \c stdout since it is not seekable.
 * \param  write_callback     See FLAC__StreamDecoderWriteCallback.  This
 *                            pointer must not be \c NULL.
 * \param  metadata_callback  See FLAC__StreamDecoderMetadataCallback.  This
 *                            pointer may be \c NULL if the callback is not
 *                            desired.
 * \param  error_callback     See FLAC__StreamDecoderErrorCallback.  This
 *                            pointer must not be \c NULL.
 * \param  client_data        This value will be supplied to callbacks in their
 *                            \a client_data argument.
 * \assert
 *    \code decoder != NULL \endcode
 *    \code file != NULL \endcode
 * \retval FLAC__StreamDecoderInitStatus
 *    \c FLAC__STREAM_DECODER_INIT_STATUS_OK if initialization was successful;
 *    see FLAC__StreamDecoderInitStatus for the meanings of other return values.
 */
FLAC_API FLAC__StreamDecoderInitStatus FLAC__stream_decoder_init_FILE(
	FLAC__StreamDecoder *decoder,
	FILE *file,
	FLAC__StreamDecoderWriteCallback write_callback,
	FLAC__StreamDecoderMetadataCallback metadata_callback,
	FLAC__StreamDecoderErrorCallback error_callback,
	void *client_data
);

/** Initialize the decoder instance to decode Ogg FLAC files.
 *
 *  This flavor of initialization sets up the decoder to decode from a
 *  plain Ogg FLAC file.  For non-stdio streams, you must use
 *  FLAC__stream_decoder_init_ogg_stream() and provide callbacks for the I/O.
 *
 *  This function should be called after FLAC__stream_decoder_new() and
 *  FLAC__stream_decoder_set_*() but before any of the
 *  FLAC__stream_decoder_process_*() functions.  Will set and return the
 *  decoder state, which will be FLAC__STREAM_DECODER_SEARCH_FOR_METADATA
 *  if initialization succeeded.
 *
 *  \note Support for Ogg FLAC in the library is optional.  If this
 *  library has been built without support for Ogg FLAC, this function
 *  will return \c FLAC__STREAM_DECODER_INIT_STATUS_UNSUPPORTED_CONTAINER.
 *
 * \param  decoder            An uninitialized decoder instance.
 * \param  file               An open FLAC file.  The file should have been
 *                            opened with mode \c "rb" and rewound.  The file
 *                            becomes owned by the decoder and should not be
 *                            manipulated by the client while decoding.
 *                            Unless \a file is \c stdin, it will be closed
 *                            when FLAC__stream_decoder_finish() is called.
 *                            Note however that seeking will not work when
 *                            decoding from \c stdout since it is not seekable.
 * \param  write_callback     See FLAC__StreamDecoderWriteCallback.  This
 *                            pointer must not be \c NULL.
 * \param  metadata_callback  See FLAC__StreamDecoderMetadataCallback.  This
 *                            pointer may be \c NULL if the callback is not
 *                            desired.
 * \param  error_callback     See FLAC__StreamDecoderErrorCallback.  This
 *                            pointer must not be \c NULL.
 * \param  client_data        This value will be supplied to callbacks in their
 *                            \a client_data argument.
 * \assert
 *    \code decoder != NULL \endcode
 *    \code file != NULL \endcode
 * \retval FLAC__StreamDecoderInitStatus
 *    \c FLAC__STREAM_DECODER_INIT_STATUS_OK if initialization was successful;
 *    see FLAC__StreamDecoderInitStatus for the meanings of other return values.
 */
FLAC_API FLAC__StreamDecoderInitStatus FLAC__stream_decoder_init_ogg_FILE(
	FLAC__StreamDecoder *decoder,
	FILE *file,
	FLAC__StreamDecoderWriteCallback write_callback,
	FLAC__StreamDecoderMetadataCallback metadata_callback,
	FLAC__StreamDecoderErrorCallback error_callback,
	void *client_data
);

/** Initialize the decoder instance to decode native FLAC files.
 *
 *  This flavor of initialization sets up the decoder to decode from a plain
 *  native FLAC file.  If POSIX fopen() semantics are not sufficient, (for
 *  example, with Unicode filenames on Windows), you must use
 *  FLAC__stream_decoder_init_FILE(), or FLAC__stream_decoder_init_stream()
 *  and provide callbacks for the I/O.
 *
 *  This function should be called after FLAC__stream_decoder_new() and
 *  FLAC__stream_decoder_set_*() but before any of the
 *  FLAC__stream_decoder_process_*() functions.  Will set and return the
 *  decoder state, which will be FLAC__STREAM_DECODER_SEARCH_FOR_METADATA
 *  if initialization succeeded.
 *
 * \param  decoder            An uninitialized decoder instance.
 * \param  filename           The name of the file to decode from.  The file will
 *                            be opened with fopen().  Use \c NULL to decode from
 *                            \c stdin.  Note that \c stdin is not seekable.
 * \param  write_callback     See FLAC__StreamDecoderWriteCallback.  This
 *                            pointer must not be \c NULL.
 * \param  metadata_callback  See FLAC__StreamDecoderMetadataCallback.  This
 *                            pointer may be \c NULL if the callback is not
 *                            desired.
 * \param  error_callback     See FLAC__StreamDecoderErrorCallback.  This
 *                            pointer must not be \c NULL.
 * \param  client_data        This value will be supplied to callbacks in their
 *                            \a client_data argument.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__StreamDecoderInitStatus
 *    \c FLAC__STREAM_DECODER_INIT_STATUS_OK if initialization was successful;
 *    see FLAC__StreamDecoderInitStatus for the meanings of other return values.
 */
FLAC_API FLAC__StreamDecoderInitStatus FLAC__stream_decoder_init_file(
	FLAC__StreamDecoder *decoder,
	const char *filename,
	FLAC__StreamDecoderWriteCallback write_callback,
	FLAC__StreamDecoderMetadataCallback metadata_callback,
	FLAC__StreamDecoderErrorCallback error_callback,
	void *client_data
);

/** Initialize the decoder instance to decode Ogg FLAC files.
 *
 *  This flavor of initialization sets up the decoder to decode from a plain
 *  Ogg FLAC file.  If POSIX fopen() semantics are not sufficient, (for
 *  example, with Unicode filenames on Windows), you must use
 *  FLAC__stream_decoder_init_ogg_FILE(), or FLAC__stream_decoder_init_ogg_stream()
 *  and provide callbacks for the I/O.
 *
 *  This function should be called after FLAC__stream_decoder_new() and
 *  FLAC__stream_decoder_set_*() but before any of the
 *  FLAC__stream_decoder_process_*() functions.  Will set and return the
 *  decoder state, which will be FLAC__STREAM_DECODER_SEARCH_FOR_METADATA
 *  if initialization succeeded.
 *
 *  \note Support for Ogg FLAC in the library is optional.  If this
 *  library has been built without support for Ogg FLAC, this function
 *  will return \c FLAC__STREAM_DECODER_INIT_STATUS_UNSUPPORTED_CONTAINER.
 *
 * \param  decoder            An uninitialized decoder instance.
 * \param  filename           The name of the file to decode from.  The file will
 *                            be opened with fopen().  Use \c NULL to decode from
 *                            \c stdin.  Note that \c stdin is not seekable.
 * \param  write_callback     See FLAC__StreamDecoderWriteCallback.  This
 *                            pointer must not be \c NULL.
 * \param  metadata_callback  See FLAC__StreamDecoderMetadataCallback.  This
 *                            pointer may be \c NULL if the callback is not
 *                            desired.
 * \param  error_callback     See FLAC__StreamDecoderErrorCallback.  This
 *                            pointer must not be \c NULL.
 * \param  client_data        This value will be supplied to callbacks in their
 *                            \a client_data argument.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__StreamDecoderInitStatus
 *    \c FLAC__STREAM_DECODER_INIT_STATUS_OK if initialization was successful;
 *    see FLAC__StreamDecoderInitStatus for the meanings of other return values.
 */
FLAC_API FLAC__StreamDecoderInitStatus FLAC__stream_decoder_init_ogg_file(
	FLAC__StreamDecoder *decoder,
	const char *filename,
	FLAC__StreamDecoderWriteCallback write_callback,
	FLAC__StreamDecoderMetadataCallback metadata_callback,
	FLAC__StreamDecoderErrorCallback error_callback,
	void *client_data
);

/** Finish the decoding process.
 *  Flushes the decoding buffer, releases resources, resets the decoder
 *  settings to their defaults, and returns the decoder state to
 *  FLAC__STREAM_DECODER_UNINITIALIZED.
 *
 *  In the event of a prematurely-terminated decode, it is not strictly
 *  necessary to call this immediately before FLAC__stream_decoder_delete()
 *  but it is good practice to match every FLAC__stream_decoder_init_*()
 *  with a FLAC__stream_decoder_finish().
 *
 * \param  decoder  An uninitialized decoder instance.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c false if MD5 checking is on AND a STREAMINFO block was available
 *    AND the MD5 signature in the STREAMINFO block was non-zero AND the
 *    signature does not match the one computed by the decoder; else
 *    \c true.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_finish(FLAC__StreamDecoder *decoder);

/** Flush the stream input.
 *  The decoder's input buffer will be cleared and the state set to
 *  \c FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC.  This will also turn
 *  off MD5 checking.
 *
 * \param  decoder  A decoder instance.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c true if successful, else \c false if a memory allocation
 *    error occurs (in which case the state will be set to
 *    \c FLAC__STREAM_DECODER_MEMORY_ALLOCATION_ERROR).
 */
FLAC_API FLAC__bool FLAC__stream_decoder_flush(FLAC__StreamDecoder *decoder);

/** Reset the decoding process.
 *  The decoder's input buffer will be cleared and the state set to
 *  \c FLAC__STREAM_DECODER_SEARCH_FOR_METADATA.  This is similar to
 *  FLAC__stream_decoder_finish() except that the settings are
 *  preserved; there is no need to call FLAC__stream_decoder_init_*()
 *  before decoding again.  MD5 checking will be restored to its original
 *  setting.
 *
 *  If the decoder is seekable, or was initialized with
 *  FLAC__stream_decoder_init*_FILE() or FLAC__stream_decoder_init*_file(),
 *  the decoder will also attempt to seek to the beginning of the file.
 *  If this rewind fails, this function will return \c false.  It follows
 *  that FLAC__stream_decoder_reset() cannot be used when decoding from
 *  \c stdin.
 *
 *  If the decoder was initialized with FLAC__stream_encoder_init*_stream()
 *  and is not seekable (i.e. no seek callback was provided or the seek
 *  callback returns \c FLAC__STREAM_DECODER_SEEK_STATUS_UNSUPPORTED), it
 *  is the duty of the client to start feeding data from the beginning of
 *  the stream on the next FLAC__stream_decoder_process() or
 *  FLAC__stream_decoder_process_interleaved() call.
 *
 * \param  decoder  A decoder instance.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c true if successful, else \c false if a memory allocation occurs
 *    (in which case the state will be set to
 *    \c FLAC__STREAM_DECODER_MEMORY_ALLOCATION_ERROR) or a seek error
 *    occurs (the state will be unchanged).
 */
FLAC_API FLAC__bool FLAC__stream_decoder_reset(FLAC__StreamDecoder *decoder);

/** Decode one metadata block or audio frame.
 *  This version instructs the decoder to decode a either a single metadata
 *  block or a single frame and stop, unless the callbacks return a fatal
 *  error or the read callback returns
 *  \c FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM.
 *
 *  As the decoder needs more input it will call the read callback.
 *  Depending on what was decoded, the metadata or write callback will be
 *  called with the decoded metadata block or audio frame.
 *
 *  Unless there is a fatal read error or end of stream, this function
 *  will return once one whole frame is decoded.  In other words, if the
 *  stream is not synchronized or points to a corrupt frame header, the
 *  decoder will continue to try and resync until it gets to a valid
 *  frame, then decode one frame, then return.  If the decoder points to
 *  a frame whose frame CRC in the frame footer does not match the
 *  computed frame CRC, this function will issue a
 *  FLAC__STREAM_DECODER_ERROR_STATUS_FRAME_CRC_MISMATCH error to the
 *  error callback, and return, having decoded one complete, although
 *  corrupt, frame.  (Such corrupted frames are sent as silence of the
 *  correct length to the write callback.)
 *
 * \param  decoder  An initialized decoder instance.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c false if any fatal read, write, or memory allocation error
 *    occurred (meaning decoding must stop), else \c true; for more
 *    information about the decoder, check the decoder state with
 *    FLAC__stream_decoder_get_state().
 */
FLAC_API FLAC__bool FLAC__stream_decoder_process_single(FLAC__StreamDecoder *decoder);

/** Decode until the end of the metadata.
 *  This version instructs the decoder to decode from the current position
 *  and continue until all the metadata has been read, or until the
 *  callbacks return a fatal error or the read callback returns
 *  \c FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM.
 *
 *  As the decoder needs more input it will call the read callback.
 *  As each metadata block is decoded, the metadata callback will be called
 *  with the decoded metadata.
 *
 * \param  decoder  An initialized decoder instance.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c false if any fatal read, write, or memory allocation error
 *    occurred (meaning decoding must stop), else \c true; for more
 *    information about the decoder, check the decoder state with
 *    FLAC__stream_decoder_get_state().
 */
FLAC_API FLAC__bool FLAC__stream_decoder_process_until_end_of_metadata(FLAC__StreamDecoder *decoder);

/** Decode until the end of the stream.
 *  This version instructs the decoder to decode from the current position
 *  and continue until the end of stream (the read callback returns
 *  \c FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM), or until the
 *  callbacks return a fatal error.
 *
 *  As the decoder needs more input it will call the read callback.
 *  As each metadata block and frame is decoded, the metadata or write
 *  callback will be called with the decoded metadata or frame.
 *
 * \param  decoder  An initialized decoder instance.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c false if any fatal read, write, or memory allocation error
 *    occurred (meaning decoding must stop), else \c true; for more
 *    information about the decoder, check the decoder state with
 *    FLAC__stream_decoder_get_state().
 */
FLAC_API FLAC__bool FLAC__stream_decoder_process_until_end_of_stream(FLAC__StreamDecoder *decoder);

/** Skip one audio frame.
 *  This version instructs the decoder to 'skip' a single frame and stop,
 *  unless the callbacks return a fatal error or the read callback returns
 *  \c FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM.
 *
 *  The decoding flow is the same as what occurs when
 *  FLAC__stream_decoder_process_single() is called to process an audio
 *  frame, except that this function does not decode the parsed data into
 *  PCM or call the write callback.  The integrity of the frame is still
 *  checked the same way as in the other process functions.
 *
 *  This function will return once one whole frame is skipped, in the
 *  same way that FLAC__stream_decoder_process_single() will return once
 *  one whole frame is decoded.
 *
 *  This function can be used in more quickly determining FLAC frame
 *  boundaries when decoding of the actual data is not needed, for
 *  example when an application is separating a FLAC stream into frames
 *  for editing or storing in a container.  To do this, the application
 *  can use FLAC__stream_decoder_skip_single_frame() to quickly advance
 *  to the next frame, then use
 *  FLAC__stream_decoder_get_decode_position() to find the new frame
 *  boundary.
 *
 *  This function should only be called when the stream has advanced
 *  past all the metadata, otherwise it will return \c false.
 *
 * \param  decoder  An initialized decoder instance not in a metadata
 *                  state.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c false if any fatal read, write, or memory allocation error
 *    occurred (meaning decoding must stop), or if the decoder
 *    is in the FLAC__STREAM_DECODER_SEARCH_FOR_METADATA or
 *    FLAC__STREAM_DECODER_READ_METADATA state, else \c true; for more
 *    information about the decoder, check the decoder state with
 *    FLAC__stream_decoder_get_state().
 */
FLAC_API FLAC__bool FLAC__stream_decoder_skip_single_frame(FLAC__StreamDecoder *decoder);

/** Flush the input and seek to an absolute sample.
 *  Decoding will resume at the given sample.  Note that because of
 *  this, the next write callback may contain a partial block.  The
 *  client must support seeking the input or this function will fail
 *  and return \c false.  Furthermore, if the decoder state is
 *  \c FLAC__STREAM_DECODER_SEEK_ERROR, then the decoder must be flushed
 *  with FLAC__stream_decoder_flush() or reset with
 *  FLAC__stream_decoder_reset() before decoding can continue.
 *
 * \param  decoder  A decoder instance.
 * \param  sample   The target sample number to seek to.
 * \assert
 *    \code decoder != NULL \endcode
 * \retval FLAC__bool
 *    \c true if successful, else \c false.
 */
FLAC_API FLAC__bool FLAC__stream_decoder_seek_absolute(FLAC__StreamDecoder *decoder, FLAC__uint64 sample);

/* \} */

#ifdef __cplusplus
}
#endif

#endif