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/* $Id$ */
/*
* Copyright (C) 2003-2007 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>
/**
* @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
};
/**
* 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 samples_per_frame Number of samples per frame. This argument
* along with clock_rate, specifies the interval
* of each clock run (or clock ticks).
* @param options By default, the callback will be called
* asynchronously (depending on the clock
* implementation backend, a thread may be
* created). If PJMEDIA_CLOCK_NO_ASYNC is set,
* application must poll the clock with
* #pjmedia_clock_wait() to let the clock runs.
* @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 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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