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/* $Id$ */
/*
* Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
* Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __PJMEDIA_CLOCK_H__
#define __PJMEDIA_CLOCK_H__
/**
* @file clock.h
* @brief Media clock.
*/
#include <pjmedia/types.h>
/**
* @defgroup PJMEDIA_PORT_CLOCK Clock/Timing
* @ingroup PJMEDIA_PORT
* @brief Various types of classes that provide timing.
* @{
The media clock/timing extends the media port concept that is explained
in @ref PJMEDIA_PORT. When clock is present in the ports
interconnection, media will flow automatically (and with correct timing too!)
from one media port to another.
There are few objects in PJMEDIA that are able to provide clock/timing
to media ports interconnection:
- @ref PJMED_SND_PORT\n
The sound device makes a good candidate as the clock source, and
PJMEDIA @ref PJMED_SND is designed so that it is able to invoke
operations according to timing driven by the sound hardware clock
(this may sound complicated, but actually it just means that
the sound device abstraction provides callbacks to be called when
it has/wants media frames).\n
See @ref PJMED_SND_PORT for more details.
- @ref PJMEDIA_MASTER_PORT\n
The master port uses @ref PJMEDIA_CLOCK as the clock source. By using
@ref PJMEDIA_MASTER_PORT, it is possible to interconnect passive
media ports and let the frames flow automatically in timely manner.\n
Please see @ref PJMEDIA_MASTER_PORT for more details.
@}
*/
/**
* @addtogroup PJMEDIA_CLOCK Clock Generator
* @ingroup PJMEDIA_PORT_CLOCK
* @brief Interface for generating clock.
* @{
*
* The clock generator provides the application with media timing,
* and it is used by the @ref PJMEDIA_MASTER_PORT for its sound clock.
*
* The clock generator may be configured to run <b>asynchronously</b>
* (the default behavior) or <b>synchronously</b>. When it is run
* asynchronously, it will call the application's callback every time
* the clock <b>tick</b> expires. When it is run synchronously,
* application must continuously polls the clock generator to synchronize
* the timing.
*/
PJ_BEGIN_DECL
/**
* Opaque declaration for media clock.
*/
typedef struct pjmedia_clock pjmedia_clock;
/**
* Options when creating the clock.
*/
enum pjmedia_clock_options
{
/**
* Prevents the clock from running asynchronously. In this case,
* application must poll the clock continuously by calling
* #pjmedia_clock_wait() in order to synchronize timing.
*/
PJMEDIA_CLOCK_NO_ASYNC = 1,
/**
* Prevent the clock from setting it's thread to highest priority.
*/
PJMEDIA_CLOCK_NO_HIGHEST_PRIO = 2
};
/**
* Type of media clock callback.
*
* @param ts Current timestamp, in samples.
* @param user_data Application data that is passed when
* the clock was created.
*/
typedef void pjmedia_clock_callback(const pj_timestamp *ts,
void *user_data);
/**
* Create media clock.
*
* @param pool Pool to allocate memory.
* @param clock_rate Number of samples per second.
* @param channel_count Number of channel.
* @param samples_per_frame Number of samples per frame. This argument
* along with clock_rate and channel_count, specifies
* the interval of each clock run (or clock ticks).
* @param options Bitmask of pjmedia_clock_options.
* @param cb Callback to be called for each clock tick.
* @param user_data User data, which will be passed to the callback.
* @param p_clock Pointer to receive the clock instance.
*
* @return PJ_SUCCESS on success, or the appropriate error
* code.
*/
PJ_DECL(pj_status_t) pjmedia_clock_create( pj_pool_t *pool,
unsigned clock_rate,
unsigned channel_count,
unsigned samples_per_frame,
unsigned options,
pjmedia_clock_callback *cb,
void *user_data,
pjmedia_clock **p_clock);
/**
* Start the clock. For clock created with asynchronous flag set to TRUE,
* this may start a worker thread for the clock (depending on the
* backend clock implementation being used).
*
* @param clock The media clock.
*
* @return PJ_SUCCES on success.
*/
PJ_DECL(pj_status_t) pjmedia_clock_start(pjmedia_clock *clock);
/**
* Stop the clock.
*
* @param clock The media clock.
*
* @return PJ_SUCCES on success.
*/
PJ_DECL(pj_status_t) pjmedia_clock_stop(pjmedia_clock *clock);
/**
* Poll the media clock, and execute the callback when the clock tick has
* elapsed. This operation is only valid if the clock is created with async
* flag set to FALSE.
*
* @param clock The media clock.
* @param wait If non-zero, then the function will block until
* a clock tick elapsed and callback has been called.
* @param ts Optional argument to receive the current
* timestamp.
*
* @return Non-zero if clock tick has elapsed, or FALSE if
* the function returns before a clock tick has
* elapsed.
*/
PJ_DECL(pj_bool_t) pjmedia_clock_wait(pjmedia_clock *clock,
pj_bool_t wait,
pj_timestamp *ts);
/**
* Destroy the clock.
*
* @param clock The media clock.
*
* @return PJ_SUCCES on success.
*/
PJ_DECL(pj_status_t) pjmedia_clock_destroy(pjmedia_clock *clock);
PJ_END_DECL
/**
* @}
*/
#endif /* __PJMEDIA_CLOCK_H__ */
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