stream_encoder.h

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/* 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
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef FLAC__STREAM_ENCODER_H
#define FLAC__STREAM_ENCODER_H

#include "export.h"
#include "format.h"
#include "stream_decoder.h"

#ifdef __cplusplus
extern "C" {
#endif


/** \file include/FLAC/stream_encoder.h
 *
 *  \brief
 *  This module contains the functions which implement the stream
 *  encoder.
 *
 *  See the detailed documentation in the
 *  \link flac_stream_encoder stream encoder \endlink module.
 */

/** \defgroup flac_encoder FLAC/ *_encoder.h: encoder interfaces
 *  \ingroup flac
 *
 *  \brief
 *  This module describes the two encoder layers provided by libFLAC.
 *
 * For encoding FLAC streams, libFLAC provides three layers of access.  The
 * lowest layer is non-seekable stream-level encoding, the next is seekable
 * stream-level encoding, and the highest layer is file-level encoding.  The
 * interfaces are described in the \link flac_stream_encoder stream encoder
 * \endlink, \link flac_seekable_stream_encoder seekable stream encoder
 * \endlink, and \link flac_file_encoder file encoder \endlink modules
 * respectively.  Typically you will choose the highest layer that your input
 * source will support.
 * The stream encoder relies on callbacks for writing the data and
 * metadata. The file encoder provides these callbacks internally and you
 * need only supply the filename.
 *
 * The stream encoder relies on callbacks for writing the data and has no
 * provisions for seeking the output.  The seekable stream encoder wraps
 * the stream encoder and also automaticallay handles the writing back of
 * metadata discovered while encoding.  However, you must provide extra
 * callbacks for seek-related operations on your output, like seek and
 * tell.  The file encoder wraps the seekable stream encoder and supplies
 * all of the callbacks internally, simplifying the processing of standard
 * files.  The only callback exposed is for progress reporting, and that
 * is optional.
 */

/** \defgroup flac_stream_encoder FLAC/stream_encoder.h: stream encoder interface
 *  \ingroup flac_encoder
 *
 *  \brief
 *  This module contains the functions which implement the stream
 *  encoder.
 *
 * The basic usage of this encoder is as follows:
 * - The program creates an instance of an encoder using
 *   FLAC__stream_encoder_new().
 * - The program overrides the default settings and sets callbacks using
 *   FLAC__stream_encoder_set_*() functions.
 * - The program initializes the instance to validate the settings and
 *   prepare for encoding using FLAC__stream_encoder_init().
 * - The program calls FLAC__stream_encoder_process() or
 *   FLAC__stream_encoder_process_interleaved() to encode data, which
 *   subsequently calls the callbacks when there is encoder data ready
 *   to be written.
 * - The program finishes the encoding with FLAC__stream_encoder_finish(),
 *   which causes the encoder to encode any data still in its input pipe,
 *   call the metadata callback with the final encoding statistics, and
 *   finally reset the encoder to the uninitialized state.
 * - The instance may be used again or deleted with
 *   FLAC__stream_encoder_delete().
 *
 * In more detail, the stream encoder functions similarly to the
 * \link flac_stream_decoder stream decoder \endlink, but has fewer
 * callbacks and more options.  Typically the user will create a new
 * instance by calling FLAC__stream_encoder_new(), then set the necessary
 * parameters and callbacks with FLAC__stream_encoder_set_*(), and
 * initialize it by calling FLAC__stream_encoder_init().
 *
 * Unlike the decoders, the stream encoder has many options that can
 * affect the speed and compression ratio.  When setting these parameters
 * you should have some basic knowledge of the format (see the
 * <A HREF="../documentation.html#format">user-level documentation</A>
 * or the <A HREF="../format.html">formal description</A>).  The
 * FLAC__stream_encoder_set_*() functions themselves do not validate the
 * values as many are interdependent.  The FLAC__stream_encoder_init()
 * function will do this, so make sure to pay attention to the state
 * returned by FLAC__stream_encoder_init() to make sure that it is
 * FLAC__STREAM_ENCODER_OK.  Any parameters that are not set before
 * FLAC__stream_encoder_init() will take on the defaults from the
 * constructor.
 *
 * The user must provide function pointers for the following callbacks:
 *
 * - Write callback - This function is called by the encoder anytime there
 *   is raw encoded data to write.  It may include metadata mixed with
 *   encoded audio frames and the data is not guaranteed to be aligned on
 *   frame or metadata block boundaries.
 * - Metadata callback - This function is called once at the end of
 *   encoding with the populated STREAMINFO structure.  This is so file
 *   encoders can seek back to the beginning of the file and write the
 *   STREAMINFO block with the correct statistics after encoding (like
 *   minimum/maximum frame size).
 *
 * The call to FLAC__stream_encoder_init() currently will also immediately
 * call the write callback several times, once with the \c fLaC signature,
 * and once for each encoded metadata block.
 *
 * After initializing the instance, the user may feed audio data to the
 * encoder in one of two ways:
 *
 * - Channel separate, through FLAC__stream_encoder_process() - The user
 *   will pass an array of pointers to buffers, one for each channel, to
 *   the encoder, each of the same length.  The samples need not be
 *   block-aligned.
 * - Channel interleaved, through
 *   FLAC__stream_encoder_process_interleaved() - The user will pass a single
 *   pointer to data that is channel-interleaved (i.e. channel0_sample0,
 *   channel1_sample0, ... , channelN_sample0, channel0_sample1, ...).
 *   Again, the samples need not be block-aligned but they must be
 *   sample-aligned, i.e. the first value should be channel0_sample0 and
 *   the last value channelN_sampleM.
 *
 * When the user is finished encoding data, it calls
 * FLAC__stream_encoder_finish(), which causes the encoder to encode any
 * data still in its input pipe, and call the metadata callback with the
 * final encoding statistics.  Then the instance may be deleted with
 * FLAC__stream_encoder_delete() or initialized again to encode another
 * stream.
 *
 * For programs that write their own metadata, but that do not know the
 * actual metadata until after encoding, it is advantageous to instruct
 * the encoder to write a PADDING block of the correct size, so that
 * instead of rewriting the whole stream after encoding, the program can
 * just overwrite the PADDING block.  If only the maximum size of the
 * metadata is known, the program can write a slightly larger padding
 * block, then split it after encoding.
 *
 * Make sure you understand how lengths are calculated.  All FLAC metadata
 * blocks have a 4 byte header which contains the type and length.  This
 * length does not include the 4 bytes of the header.  See the format page
 * for the specification of metadata blocks and their lengths.
 *
 * \note
 * The "set" functions may only be called when the encoder is in the
 * state FLAC__STREAM_ENCODER_UNINITIALIZED, i.e. after
 * FLAC__stream_encoder_new() or FLAC__stream_encoder_finish(), but
 * before FLAC__stream_encoder_init().  If this is the case they will
 * return \c true, otherwise \c false.
 *
 * \note
 * FLAC__stream_encoder_finish() resets all settings to the constructor
 * defaults, including the callbacks.
 *
 * \{
 */


/** State values for a FLAC__StreamEncoder
 *
 *  The encoder's state can be obtained by calling FLAC__stream_encoder_get_state().
 */
typedef enum {

	FLAC__STREAM_ENCODER_OK = 0,
	/**< The encoder is in the normal OK state. */

	FLAC__STREAM_ENCODER_VERIFY_DECODER_ERROR,
	/**< An error occurred in the underlying verify stream decoder;
	 * check FLAC__stream_encoder_get_verify_decoder_state().
	 */

	FLAC__STREAM_ENCODER_VERIFY_MISMATCH_IN_AUDIO_DATA,
	/**< The verify decoder detected a mismatch between the original
	 * audio signal and the decoded audio signal.
	 */

	FLAC__STREAM_ENCODER_INVALID_CALLBACK,
	/**< The encoder was initialized before setting all the required callbacks. */

	FLAC__STREAM_ENCODER_INVALID_NUMBER_OF_CHANNELS,
	/**< The encoder has an invalid setting for number of channels. */

	FLAC__STREAM_ENCODER_INVALID_BITS_PER_SAMPLE,
	/**< The encoder has an invalid setting for bits-per-sample.
	 * FLAC supports 4-32 bps but the reference encoder currently supports
	 * only up to 24 bps.
	 */

	FLAC__STREAM_ENCODER_INVALID_SAMPLE_RATE,
	/**< The encoder has an invalid setting for the input sample rate. */

	FLAC__STREAM_ENCODER_INVALID_BLOCK_SIZE,
	/**< The encoder has an invalid setting for the block size. */

	FLAC__STREAM_ENCODER_INVALID_MAX_LPC_ORDER,
	/**< The encoder has an invalid setting for the maximum LPC order. */

	FLAC__STREAM_ENCODER_INVALID_QLP_COEFF_PRECISION,
	/**< The encoder has an invalid setting for the precision of the quantized linear predictor coefficients. */

	FLAC__STREAM_ENCODER_MID_SIDE_CHANNELS_MISMATCH,
	/**< Mid/side coding was specified but the number of channels is not equal to 2. */

	FLAC__STREAM_ENCODER_MID_SIDE_SAMPLE_SIZE_MISMATCH,
	/**< Deprecated. */

	FLAC__STREAM_ENCODER_ILLEGAL_MID_SIDE_FORCE,
	/**< Loose mid/side coding was specified but mid/side coding was not. */

	FLAC__STREAM_ENCODER_BLOCK_SIZE_TOO_SMALL_FOR_LPC_ORDER,
	/**< The specified block size is less than the maximum LPC order. */

	FLAC__STREAM_ENCODER_NOT_STREAMABLE,
	/**< The encoder is bound to the "streamable subset" but other settings violate it. */

	FLAC__STREAM_ENCODER_FRAMING_ERROR,
	/**< An error occurred while writing the stream; usually, the write_callback returned an error. */

	FLAC__STREAM_ENCODER_INVALID_METADATA,
	/**< The metadata input to the encoder is invalid, in one of the following ways:
	 * - FLAC__stream_encoder_set_metadata() was called with a null pointer but a block count > 0
	 * - One of the metadata blocks contains an undefined type
	 * - It contains an illegal CUESHEET as checked by FLAC__format_cuesheet_is_legal()
	 * - It contains an illegal SEEKTABLE as checked by FLAC__format_seektable_is_legal()
	 * - It contains more than one SEEKTABLE block or more than one VORBIS_COMMENT block
	 */

	FLAC__STREAM_ENCODER_FATAL_ERROR_WHILE_ENCODING,
	/**< An error occurred while writing the stream; usually, the write_callback returned an error. */

	FLAC__STREAM_ENCODER_FATAL_ERROR_WHILE_WRITING,
	/**< The write_callback returned an error. */

	FLAC__STREAM_ENCODER_MEMORY_ALLOCATION_ERROR,
	/**< Memory allocation failed. */

	FLAC__STREAM_ENCODER_ALREADY_INITIALIZED,
	/**< FLAC__stream_encoder_init() was called when the encoder was
	 * already initialized, usually because
	 * FLAC__stream_encoder_finish() was not called.
	 */

	FLAC__STREAM_ENCODER_UNINITIALIZED
	/**< The encoder is in the uninitialized state. */

} FLAC__StreamEncoderState;

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

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

	FLAC__STREAM_ENCODER_WRITE_STATUS_OK = 0,
	/**< The write was OK and encoding can continue. */

	FLAC__STREAM_ENCODER_WRITE_STATUS_FATAL_ERROR
	/**< An unrecoverable error occurred.  The encoder will return from the process call. */

} FLAC__StreamEncoderWriteStatus;

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


/***********************************************************************
 *
 * class FLAC__StreamEncoder
 *
 ***********************************************************************/

struct FLAC__StreamEncoderProtected;
struct FLAC__StreamEncoderPrivate;
/** The opaque structure definition for the stream encoder type.
 *  See the \link flac_stream_encoder stream encoder module \endlink
 *  for a detailed description.
 */
typedef struct {
	struct FLAC__StreamEncoderProtected *protected_; /* avoid the C++ keyword 'protected' */
	struct FLAC__StreamEncoderPrivate *private_; /* avoid the C++ keyword 'private' */
} FLAC__StreamEncoder;

/** Signature for the write callback.
 *  See FLAC__stream_encoder_set_write_callback() for more info.
 *
 * \param  encoder  The encoder instance calling the callback.
 * \param  buffer   An array of encoded data of length \a bytes.
 * \param  bytes    The byte length of \a buffer.
 * \param  samples  The number of samples encoded by \a buffer.
 *                  \c 0 has a special meaning; see
 *                  FLAC__stream_encoder_set_write_callback().
 * \param  current_frame  The number of the current frame being encoded.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_encoder_set_client_data().
 * \retval FLAC__StreamEncoderWriteStatus
 *    The callee's return status.
 */
typedef FLAC__StreamEncoderWriteStatus (*FLAC__StreamEncoderWriteCallback)(const FLAC__StreamEncoder *encoder, const FLAC__byte buffer[], unsigned bytes, unsigned samples, unsigned current_frame, void *client_data);

/** Signature for the metadata callback.
 *  See FLAC__stream_encoder_set_metadata_callback() for more info.
 *
 * \param  encoder      The encoder instance calling the callback.
 * \param  metadata     The final populated STREAMINFO block.
 * \param  client_data  The callee's client data set through
 *                      FLAC__stream_encoder_set_client_data().
 */
typedef void (*FLAC__StreamEncoderMetadataCallback)(const FLAC__StreamEncoder *encoder, const FLAC__StreamMetadata *metadata, void *client_data);