voice-gateway-service/pjproject/pjmedia/include/pjmedia/clock.h

/* 
 * 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

/**
 * Media clock source.
 */
typedef struct pjmedia_clock_src
{
    pjmedia_type    media_type;     /**< Media type.                */
    unsigned        clock_rate;     /**< Clock rate.                */
    unsigned        ptime_usec;     /**< Frame interval (in usec).  */
    /**
     * The timestamp field holds an increasing value in samples and its
     * value is expected to be increased by clock_rate samples per second.
     */
    pj_timestamp    timestamp;
    /**
     * Timestamp's last update. The last_update field contains a value in
     * ticks, and it is expected to be increased by pj_get_timestamp_freq()
     * ticks per second.
     */
    pj_timestamp    last_update;
} pjmedia_clock_src;

/**
 * This is an auxiliary function to initialize the media clock source.
 *
 * @param clocksrc          The clock source to be initialized.
 * @param media_type        The media type.
 * @param clock_rate        The clock rate.
 * @param ptime_usec        Media frame interval (in usec).
 *
 * @return                  PJ_SUCCESS on success.
 */
PJ_DECL(pj_status_t) pjmedia_clock_src_init( pjmedia_clock_src *clocksrc,
                                             pjmedia_type media_type,
                                             unsigned clock_rate,
                                             unsigned ptime_usec );

/**
 * This function updates the clock source's timestamp. Application should
 * use this function instead of updating the timestamp directly since this
 * function will also update the last_update field of the clock source.
 *
 * @param clocksrc          The clock source to be updated.
 * @param timestamp         The new timestamp, can be NULL if the current
 *                          timestamp does not change (in this case it
 *                          will only update the last_update field).
 *
 * @return                  PJ_SUCCESS on success.
 */
PJ_DECL(pj_status_t) pjmedia_clock_src_update( pjmedia_clock_src *clocksrc,
                                               const pj_timestamp *timestamp );

/**
 * This function gets the clock source's current timestamp. Application
 * should use this function instead of accessing the timestamp directly
 * since this function will calculate the predicted timestamp for current
 * time, based on the values of timestamp, last_update, and clock_rate.
 *
 * @param clocksrc          The clock source.
 * @param timestamp         Argument to receive the current timestamp
 *
 * @return                  PJ_SUCCESS on success.
 */
PJ_DECL(pj_status_t)
pjmedia_clock_src_get_current_timestamp( const pjmedia_clock_src *clocksrc,
                                         pj_timestamp *timestamp);

/**
 * This function gets the clock source's time in msec.
 *
 * @param clocksrc          The clock source.
 *
 * @return                  The clock source's time (in msec).
 */
PJ_DECL(pj_uint32_t)
pjmedia_clock_src_get_time_msec( const pjmedia_clock_src *clocksrc );


/**
 * 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
};


typedef struct pjmedia_clock_param
{
    /**
     * The frame interval, in microseconds.
     */
    unsigned usec_interval;
    /**
     * The media clock rate, to determine timestamp
     * increment for each call.
     */
    unsigned clock_rate;
} pjmedia_clock_param;

/**
 * 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. This creates a media clock object that will run
 * periodically at an interval that is calculated from the audio parameters.
 * Once created, application must call #pjmedia_clock_start() to actually
 * start the clock.
 *
 * @see pjmedia_clock_create2()
 *
 * @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);


/**
 * Create media clock. This creates a media clock object that will run
 * periodically at the specified interval. Once created, application must
 * call #pjmedia_clock_start() to actually start the clock.
 *
 * @param pool              Pool to allocate memory.
 * @param param             The clock parameter.
 * @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_create2(pj_pool_t *pool,
                                           const pjmedia_clock_param *param,
                                           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. When the function returns PJ_SUCCESS, it is guaranteed
 * that the clock thread (if any) has stopped and the callback has completed.
 * But if the function is called from within the clock's callback itself,
 * the callback will still be running until completion. In that case, 
 * the function will only stop future callbacks and returns PJ_EBUSY.
 *
 * @param clock             The media clock.
 *
 * @return                  PJ_SUCCES on success, or PJ_EBUSY.
 */
PJ_DECL(pj_status_t) pjmedia_clock_stop(pjmedia_clock *clock);


/**
 * Modify the clock's parameter.
 *
 * @param clock             The media clock.
 * @param param             The clock's new parameter.
 * @return                  PJ_SUCCES on success.
 */
PJ_DECL(pj_status_t) pjmedia_clock_modify(pjmedia_clock *clock,
                                          const pjmedia_clock_param *param);


/**
 * 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__ */