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Josh Coalson
2002-07-25 05:35:16 +00:00
parent dea419a064
commit 03706dce5e
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include/FLAC/stream_decoder.h
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@@ -27,41 +27,255 @@ 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 three decoder layers provided by libFLAC.
*
* For decoding FLAC streams, libFLAC provides three layers of access. The
* lowest layer is non-seekable stream-level decoding, the next is seekable
* stream-level decoding, and the highest layer is file-level decoding. The
* interfaces are described in the \link flac_stream_decoder stream decoder
* \endlink, \link flac_seekable_stream_decoder seekable stream decoder
* \endlink, and \link flac_file_decoder file decoder \endlink modules
* respectively. Typically you will choose the highest layer that your input
* source will support.
*
* The stream decoder relies on callbacks for all input and output and has no
* provisions for seeking. The seekable stream decoder wraps the stream
* decoder and exposes functions for seeking. However, you must provide
* extra callbacks for seek-related operations on your stream, like seek and
* tell. The file decoder wraps the seekable stream decoder and supplies
* most of the callbacks internally, simplifying the processing of standard
* files.
*/
/** \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 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 and sets callbacks for
* reading, writing, error reporting, and metadata reporting using
* FLAC__stream_decoder_set_*() functions.
* - The program initializes the instance to validate the settings and
* prepare for decoding using FLAC__stream_decoder_init().
* - 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 set the callbacks and client data, and call
* FLAC__stream_decoder_init(). The required callbacks are:
*
* - Read callback - This 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.
* - Write callback - This function will be called when the decoder has
* decoded a single frame of data. The decoder will pass the frame
* metadata as well as an array of pointers (one for each channel)
* pointing to the decoded audio.
* - Metadata callback - This function will be called when the decoder has
* decoded a metadata block. There will always be one STREAMINFO block
* per stream, 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 STREAMINFO block; you can instruct
* the decoder to pass or filter other blocks with
* FLAC__stream_decoder_set_metadata_*() calls.
* - Error callback - This function will be called whenever an error occurs
* during decoding.
*
* Once the decoder is initialized, your program will call one of several
* functions to start the decoding process:
*
* - FLAC__stream_decoder_process_whole_stream() - Tells the decoder to
* start and continue processing the stream until the read callback
* returns FLAC__STREAM_DECODER_READ_END_OF_STREAM or
* FLAC__STREAM_DECODER_READ_ABORT.
* - FLAC__stream_decoder_process_metadata() - Tells the decoder to start
* processing the stream and stop upon reaching the first audio frame.
* - FLAC__stream_decoder_process_one_frame() - Tells the decoder to
* process one audio frame and return. The decoder must have processed
* all metadata first before calling this function.
* - FLAC__stream_decoder_process_remaining_frames() - Tells the decoder to
* process all remaining frames. The decoder must have processed all
* metadata first but may also have processed frames with
* FLAC__stream_decoder_process_one_frame().
*
* 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.
*
* Note that the stream decoder has no real concept of stream position, it
* just converts data. To seek within a stream the callbacks have only to
* flush the decoder using FLAC__stream_decoder_flush() and start feeding
* data from the new position through the read callback. The seekable
* stream decoder does just this.
*
* \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_ABORTED,
/**< The decoder was aborted by the read callback. */
FLAC__STREAM_DECODER_UNPARSEABLE_STREAM,
/**< The decoder encountered reserved fields in use in the stream. */
FLAC__STREAM_DECODER_MEMORY_ALLOCATION_ERROR,
/**< An error occurred allocating memory. */
FLAC__STREAM_DECODER_ALREADY_INITIALIZED,
/**< FLAC__stream_decoder_init() was called when the decoder was
* already initialized, usually because
* FLAC__stream_decoder_finish() was not called.
*/
FLAC__STREAM_DECODER_INVALID_CALLBACK,
/**< FLAC__stream_decoder_init() was called without all callbacks being set. */
FLAC__STREAM_DECODER_UNINITIALIZED
/**< The decoder is in the uninitialized state. */
} 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 const char * const FLAC__StreamDecoderStateString[];
/** 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 at the end of the stream. */
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 const char * const FLAC__StreamDecoderReadStatusString[];
/** 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 const char * const FLAC__StreamDecoderWriteStatusString[];
/** Possible values passed in to the FLAC__StreamDecoder error callback.
*/
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__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 const char * const FLAC__StreamDecoderErrorStatusString[];
/***********************************************************************
*
* class FLAC__StreamDecoder
@@ -70,60 +284,148 @@ extern const char * const FLAC__StreamDecoderErrorStatusString[];
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;
/***********************************************************************
*
* Class constructor/destructor
*
***********************************************************************/
/*
* Any parameters that are not set before FLAC__stream_decoder_init()
* will take on the defaults from the constructor, shown below.
* For more on what the parameters mean, see the documentation.
/** 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.
*
* (*read_callback)() (DEFAULT: NULL ) The callbacks are the only values that MUST be set before FLAC__stream_decoder_init()
* (*write_callback)() (DEFAULT: NULL )
* (*metadata_callback)() (DEFAULT: NULL )
* (*error_callback)() (DEFAULT: NULL )
* void* client_data (DEFAULT: NULL ) passed back through the callbacks
* metadata_respond/ignore By default, only the STREAMINFO block is returned via metadata_callback()
* \retval FLAC__StreamDecoder*
* \c NULL if there was an error allocating memory, else the new instance.
*/
FLAC__StreamDecoder *FLAC__stream_decoder_new();
/** Free an decoder instance. Deletes the object pointed to by \a decoder.
*
* \param decoder A pointer to an existing decoder.
* \assert
* \code decoder != NULL \endcode
*/
void FLAC__stream_decoder_delete(FLAC__StreamDecoder *);
/***********************************************************************
*
* Public class method prototypes
*
***********************************************************************/
/*
* Various "set" methods. These 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 true, otherwise false.
/** Set the read callback.
* 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.
*
* NOTE that these functions do not validate the values as many are
* interdependent. The FLAC__stream_decoder_init() function will do
* this, so make sure to pay attention to the state returned by
* FLAC__stream_decoder_init().
* \note
* The callback is mandatory and must be set before initialization.
*
* Any parameters that are not set before FLAC__stream_decoder_init()
* will take on the defaults from the constructor. NOTE that
* FLAC__stream_decoder_flush() or FLAC__stream_decoder_reset() do
* NOT reset the values to the constructor defaults.
* \default \c NULL
* \param decoder An decoder instance to set.
* \param value See above.
* \assert
* \code decoder != NULL \endcode
* \code value != NULL \endcode
* \retval FLAC__bool
* \c false if the decoder is already initialized, else \c true.
*/
FLAC__bool FLAC__stream_decoder_set_read_callback(FLAC__StreamDecoder *decoder, FLAC__StreamDecoderReadStatus (*value)(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data));
/** Set the write callback.
* The supplied function will be called when the decoder has decoded a
* single frame of data. The decoder will pass the frame metadata as
* well as an array of pointers (one for each channel) pointing to the
* decoded audio.
*
* \note
* The callback is mandatory and must be set before initialization.
*
* \default \c NULL
* \param decoder An decoder instance to set.
* \param value See above.
* \assert
* \code decoder != NULL \endcode
* \code value != NULL \endcode
* \retval FLAC__bool
* \c false if the decoder is already initialized, else \c true.
*/
FLAC__bool FLAC__stream_decoder_set_write_callback(FLAC__StreamDecoder *decoder, FLAC__StreamDecoderWriteStatus (*value)(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data));
/** Set the metadata callback.
* The supplied function will be called when the decoder has decoded a
* metadata block. There will always be one STREAMINFO block per stream,
* 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 STREAMINFO block; you can instruct
* the decoder to pass or filter other blocks with
* FLAC__stream_decoder_set_metadata_*() calls.
*
* \note
* The callback is mandatory and must be set before initialization.
*
* \default \c NULL
* \param decoder An decoder instance to set.
* \param value See above.
* \assert
* \code decoder != NULL \endcode
* \code value != NULL \endcode
* \retval FLAC__bool
* \c false if the decoder is already initialized, else \c true.
*/
FLAC__bool FLAC__stream_decoder_set_metadata_callback(FLAC__StreamDecoder *decoder, void (*value)(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data));
/** Set the error callback.
* The supplied function will be called whenever an error occurs during
* decoding.
*
* \note
* The callback is mandatory and must be set before initialization.
*
* \default \c NULL
* \param decoder An decoder instance to set.
* \param value See above.
* \assert
* \code decoder != NULL \endcode
* \code value != NULL \endcode
* \retval FLAC__bool
* \c false if the decoder is already initialized, else \c true.
*/
FLAC__bool FLAC__stream_decoder_set_error_callback(FLAC__StreamDecoder *decoder, void (*value)(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data));
/** Set the client data to be passed back to callbacks.
* This value will be supplied to callbacks in their \a client_data
* argument.
*
* \default \c NULL
* \param decoder An decoder instance to set.
* \param value See above.
* \assert
* \code decoder != NULL \endcode
* \retval FLAC__bool
* \c false if the decoder is already initialized, else \c true.
*/
FLAC__bool FLAC__stream_decoder_set_client_data(FLAC__StreamDecoder *decoder, void *value);
/*
* These deserve special attention. By default, the decoder only calls the
* metadata_callback for the STREAMINFO block. These functions allow you to
@@ -138,6 +440,9 @@ FLAC__bool FLAC__stream_decoder_set_client_data(FLAC__StreamDecoder *decoder, vo
* STREAMINFO and SEEKTABLE blocks are always parsed and used internally, but
* they still can legally be filtered from the metadata_callback here.
*/
/*
* metadata_respond/ignore By default, only the STREAMINFO block is returned via metadata_callback()
*/
FLAC__bool FLAC__stream_decoder_set_metadata_respond(FLAC__StreamDecoder *decoder, FLAC__MetadataType type);
FLAC__bool FLAC__stream_decoder_set_metadata_respond_application(FLAC__StreamDecoder *decoder, const FLAC__byte id[4]);
FLAC__bool FLAC__stream_decoder_set_metadata_respond_all(FLAC__StreamDecoder *decoder);
@@ -187,6 +492,8 @@ FLAC__bool FLAC__stream_decoder_process_metadata(FLAC__StreamDecoder *decoder);
FLAC__bool FLAC__stream_decoder_process_one_frame(FLAC__StreamDecoder *decoder);
FLAC__bool FLAC__stream_decoder_process_remaining_frames(FLAC__StreamDecoder *decoder);
/* \} */
#ifdef __cplusplus
}
#endif