gecko/media/liboggz/include/oggz/oggz_write.h

/*
   Copyright (C) 2003 Commonwealth Scientific and Industrial Research
   Organisation (CSIRO) Australia

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   - Neither the name of CSIRO Australia nor the names of its
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   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 ORGANISATION OR
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*/

#ifndef __OGGZ_WRITE_H__
#define __OGGZ_WRITE_H__

/** \file
 * Interfaces for writing Ogg files and streams
 */

/** \defgroup force_feed Writing by force feeding Oggz
 *
 * Force feeding involves synchronously:
 * - Creating an \a ogg_packet structure
 * - Adding it to the packet queue with oggz_write_feed()
 * - Calling oggz_write() or oggz_write_output(), repeatedly as necessary,
 *   to generate the Ogg bitstream.
 *
 * This process is illustrated in the following diagram:
 *
 * \image html forcefeed.png
 * \image latex forcefeed.eps "Force Feeding Oggz" width=10cm
 *
 * The following example code generates a stream of ten packets, each
 * containing a single byte ('A', 'B', ... , 'J'):
 *
 * \include write-feed.c
 */

/** \defgroup hungry Writing with OggzHungry callbacks
 *
 * You can add packets to the Oggz packet queue only when it is "hungry"
 * by providing an OggzHungry callback.
 *
 * An OggzHungry callback will:
 * - Create an \a ogg_packet structure
 * - Add it to the packet queue with oggz_write_feed()
 *
 * Once you have set such a callback with oggz_write_set_hungry_callback(),
 * simply call oggz_write() or oggz_write_output() repeatedly, and Oggz
 * will call your callback to provide packets when it is hungry.
 *
 * This process is illustrated in the following diagram:
 *
 * \image html hungry.png
 * \image latex hungry.eps "Using OggzHungry" width=10cm
 *
 * The following example code generates a stream of ten packets, each
 * containing a single byte ('A', 'B', ... , 'J'):
 *
 * \include write-hungry.c
 */

/** \defgroup write_api Oggz Write API
 *
 * Oggz maintains a packet queue, such that you can independently add
 * packets to the queue and write an Ogg bitstream.
 * There are two complementary methods for adding packets to the
 * packet queue.
 *
 * - by \link force_feed force feeding Oggz \endlink
 * - by using \link hungry OggzHungry \endlink callbacks
 *
 * As each packet is enqueued, its validity is checked against the framing
 * constraints outlined in the \link basics Ogg basics \endlink section.
 * If it does not pass these constraints, oggz_write_feed() will fail with
 * an appropriate error code.
 *
 * \note
 * - When writing, you can ensure that a packet starts on a new page
 *   by setting the \a flush parameter of oggz_write_feed() to
 *   \a OGGZ_FLUSH_BEFORE when enqueuing it.
 *   Similarly you can ensure that the last page a packet is written into
 *   won't contain any following packets by setting the \a flush parameter
 *   of oggz_write_feed() to \a OGGZ_FLUSH_AFTER.
 * - The \a OGGZ_FLUSH_BEFORE and \a OGGZ_FLUSH_AFTER flags can be bitwise
 *   OR'd together to ensure that the packet will not share any pages with
 *   any other packets, either before or after.
 *
 * \{
 */

/**
 * This is the signature of a callback which Oggz will call when \a oggz
 * is \link hungry hungry \endlink.
 *
 * \param oggz The OGGZ handle
 * \param empty A value of 1 indicates that the packet queue is currently
 *        empty. A value of 0 indicates that the packet queue is not empty.
 * \param user_data A generic pointer you have provided earlier
 * \retval 0 Continue
 * \retval non-zero Instruct Oggz to stop.
 */
typedef int (*OggzWriteHungry) (OGGZ * oggz, int empty, void * user_data);

/**
 * Set a callback for Oggz to call when \a oggz
 * is \link hungry hungry \endlink.
 *
 * \param oggz An OGGZ handle previously opened for writing
 * \param hungry Your callback function
 * \param only_when_empty When to call: a value of 0 indicates that
 * Oggz should call \a hungry() after each and every packet is written;
 * a value of 1 indicates that Oggz should call \a hungry() only when
 * its packet queue is empty
 * \param user_data Arbitrary data you wish to pass to your callback
 * \retval 0 Success
 * \retval OGGZ_ERR_BAD_OGGZ \a oggz does not refer to an existing OGGZ
 * \retval OGGZ_ERR_INVALID Operation not suitable for this OGGZ
 * \note Passing a value of 0 for \a only_when_empty allows you to feed
 * new packets into \a oggz's packet queue on the fly.
 */
int oggz_write_set_hungry_callback (OGGZ * oggz,
				    OggzWriteHungry hungry,
				    int only_when_empty,
				    void * user_data);
/**
 * Add a packet to \a oggz's packet queue.
 * \param oggz An OGGZ handle previously opened for writing
 * \param op An ogg_packet with all fields filled in
 * \param serialno Identify the logical bitstream in \a oggz to add the
 * packet to
 * \param flush Bitmask of OGGZ_FLUSH_BEFORE, OGGZ_FLUSH_AFTER
 * \param guard A guard for nocopy, NULL otherwise
 * \retval 0 Success
 * \retval OGGZ_ERR_BAD_GUARD \a guard specified has non-zero initialization
 * \retval OGGZ_ERR_BOS Packet would be bos packet of a new logical bitstream,
 *         but oggz has already written one or more non-bos packets in
 *         other logical bitstreams,
 *         and \a oggz is not flagged OGGZ_NONSTRICT
 * \retval OGGZ_ERR_EOS The logical bitstream identified by \a serialno is
 *         already at eos,
 *         and \a oggz is not flagged OGGZ_NONSTRICT
 * \retval OGGZ_ERR_BAD_BYTES \a op->bytes is invalid,
 *         and \a oggz is not flagged OGGZ_NONSTRICT
 * \retval OGGZ_ERR_BAD_B_O_S \a op->b_o_s is invalid,
 *         and \a oggz is not flagged OGGZ_NONSTRICT
 * \retval OGGZ_ERR_BAD_GRANULEPOS \a op->granulepos is less than that of
 *         an earlier packet within this logical bitstream,
 *         and \a oggz is not flagged OGGZ_NONSTRICT
 * \retval OGGZ_ERR_BAD_PACKETNO \a op->packetno is less than that of an
 *         earlier packet within this logical bitstream,
 *         and \a oggz is not flagged OGGZ_NONSTRICT
 * \retval OGGZ_ERR_BAD_SERIALNO \a serialno does not identify an existing
 *         logical bitstream in \a oggz,
 *         and \a oggz is not flagged OGGZ_NONSTRICT
 *         or \a serialno is equal to -1, or \a serialno does not fit in
 *         32 bits, ie. within the range (-(2^31), (2^31)-1)
 * \retval OGGZ_ERR_BAD_OGGZ \a oggz does not refer to an existing OGGZ
 * \retval OGGZ_ERR_INVALID Operation not suitable for this OGGZ
 *
 * \note If \a op->b_o_s is initialized to \a -1 before calling
 *       oggz_write_feed(), Oggz will fill it in with the appropriate
 *       value; ie. 1 for the first packet of a new stream, and 0 otherwise.
 */
int oggz_write_feed (OGGZ * oggz, ogg_packet * op, long serialno, int flush,
		     int * guard);

/**
 * Output data from an OGGZ handle. Oggz will call your write callback
 * as needed.
 *
 * \param oggz An OGGZ handle previously opened for writing
 * \param buf A memory buffer
 * \param n A count of bytes to output
 * \retval "> 0" The number of bytes successfully output
 * \retval 0 End of stream
 * \retval OGGZ_ERR_RECURSIVE_WRITE Attempt to initiate writing from
 * within an OggzHungry callback
 * \retval OGGZ_ERR_BAD_OGGZ \a oggz does not refer to an existing OGGZ
 * \retval OGGZ_ERR_INVALID Operation not suitable for this OGGZ
 * \retval OGGZ_ERR_STOP_OK Writing was stopped by an OggzHungry callback
 * returning OGGZ_STOP_OK
 * \retval OGGZ_ERR_STOP_ERR Reading was stopped by an OggzHungry callback
 * returning OGGZ_STOP_ERR
 */
long oggz_write_output (OGGZ * oggz, unsigned char * buf, long n);

/**
 * Write n bytes from an OGGZ handle. Oggz will call your write callback
 * as needed.
 *
 * \param oggz An OGGZ handle previously opened for writing
 * \param n A count of bytes to be written
 * \retval "> 0" The number of bytes successfully output
 * \retval 0 End of stream
 * \retval OGGZ_ERR_RECURSIVE_WRITE Attempt to initiate writing from
 * within an OggzHungry callback
 * \retval OGGZ_ERR_BAD_OGGZ \a oggz does not refer to an existing OGGZ
 * \retval OGGZ_ERR_INVALID Operation not suitable for this OGGZ
 * \retval OGGZ_ERR_STOP_OK Writing was stopped by an OggzHungry callback
 * returning OGGZ_STOP_OK
 * \retval OGGZ_ERR_STOP_ERR Reading was stopped by an OggzHungry callback
 * returning OGGZ_STOP_ERR
 */
long oggz_write (OGGZ * oggz, long n);

/**
 * Query the number of bytes in the next page to be written.
 *
 * \param oggz An OGGZ handle previously opened for writing
 * \retval ">= 0" The number of bytes in the next page
 * \retval OGGZ_ERR_BAD_OGGZ \a oggz does not refer to an existing OGGZ
 * \retval OGGZ_ERR_INVALID Operation not suitable for this OGGZ
 */
long oggz_write_get_next_page_size (OGGZ * oggz);

/** \}
 */

#endif /* __OGGZ_WRITE_H__ */