GST_CLOCK_TIME_IS_VALID()

#define GST_CLOCK_TIME_IS_VALID(time)   (((GstClockTime)(time)) != GST_CLOCK_TIME_NONE)

Tests if a given GstClockTime represents a valid defined time.

GST_CLOCK_STIME_IS_VALID()

#define GST_CLOCK_STIME_IS_VALID(time)   (((GstClockTimeDiff)(time)) != GST_CLOCK_STIME_NONE)

Tests if a given GstClockTimeDiff of gint64 represents a valid defined time.

Since: 1.6

GST_TIME_AS_SECONDS()

#define GST_TIME_AS_SECONDS(time)  ((time) / GST_SECOND)

Convert a GstClockTime to seconds.

GST_TIME_AS_MSECONDS()

#define GST_TIME_AS_MSECONDS(time) ((time) / G_GINT64_CONSTANT (1000000))

Convert a GstClockTime to milliseconds (1/1000 of a second).

GST_TIME_AS_USECONDS()

#define GST_TIME_AS_USECONDS(time) ((time) / G_GINT64_CONSTANT (1000))

Convert a GstClockTime to microseconds (1/1000000 of a second).

GST_TIME_AS_NSECONDS()

#define GST_TIME_AS_NSECONDS(time) (time)

Convert a GstClockTime to nanoseconds (1/1000000000 of a second).

GST_CLOCK_DIFF()

#define GST_CLOCK_DIFF(s, e)            (GstClockTimeDiff)((e) - (s))

Calculate a difference between two clock times as a GstClockTimeDiff. The difference is calculated as e - s .

GST_TIMEVAL_TO_TIME()

#define GST_TIMEVAL_TO_TIME(tv)         (GstClockTime)((tv).tv_sec * GST_SECOND + (tv).tv_usec * GST_USECOND)

Convert a GTimeVal to a GstClockTime.

GST_TIME_TO_TIMEVAL()

#define             GST_TIME_TO_TIMEVAL(t,tv)

Convert a GstClockTime to a GTimeVal

GST_TIMESPEC_TO_TIME()

#define GST_TIMESPEC_TO_TIME(ts)        (GstClockTime)((ts).tv_sec * GST_SECOND + (ts).tv_nsec * GST_NSECOND)

Convert a struct timespec (see man pselect) to a GstClockTime.

GST_TIME_TO_TIMESPEC()

#define             GST_TIME_TO_TIMESPEC(t,ts)

Convert a GstClockTime to a struct timespec (see man pselect)

GstClockCallback ()

gboolean
(*GstClockCallback) (GstClock *clock,
                     GstClockTime time,
                     GstClockID id,
                     gpointer user_data);

The function prototype of the callback.

GST_CLOCK_ENTRY()

#define GST_CLOCK_ENTRY(entry)          ((GstClockEntry *)(entry))

Cast to a clock entry

GST_CLOCK_ENTRY_CLOCK()

#define GST_CLOCK_ENTRY_CLOCK(entry)    ((entry)->clock)

Get the owner clock of the entry

GST_CLOCK_ENTRY_TYPE()

#define GST_CLOCK_ENTRY_TYPE(entry)     ((entry)->type)

Get the type of the clock entry

GST_CLOCK_ENTRY_TIME()

#define GST_CLOCK_ENTRY_TIME(entry)     ((entry)->time)

Get the requested time of this entry

GST_CLOCK_ENTRY_INTERVAL()

#define GST_CLOCK_ENTRY_INTERVAL(entry) ((entry)->interval)

Get the interval of this periodic entry

GST_CLOCK_ENTRY_STATUS()

#define GST_CLOCK_ENTRY_STATUS(entry)   ((entry)->status)

The status of the entry

GST_CLOCK_FLAGS()

#define GST_CLOCK_FLAGS(clock)  GST_OBJECT_FLAGS(clock)

Gets the GstClockFlags clock flags.

gst_clock_add_observation ()

gboolean
gst_clock_add_observation (GstClock *clock,
                           GstClockTime slave,
                           GstClockTime master,
                           gdouble *r_squared);

The time master of the master clock and the time slave of the slave clock are added to the list of observations. If enough observations are available, a linear regression algorithm is run on the observations and clock is recalibrated.

If this functions returns TRUE, r_squared will contain the correlation coefficient of the interpolation. A value of 1.0 means a perfect regression was performed. This value can be used to control the sampling frequency of the master and slave clocks.

gst_clock_add_observation_unapplied ()

gboolean
gst_clock_add_observation_unapplied (GstClock *clock,
                                     GstClockTime slave,
                                     GstClockTime master,
                                     gdouble *r_squared,
                                     GstClockTime *internal,
                                     GstClockTime *external,
                                     GstClockTime *rate_num,
                                     GstClockTime *rate_denom);

Add a clock observation to the internal slaving algorithm the same as gst_clock_add_observation(), and return the result of the master clock estimation, without updating the internal calibration.

The caller can then take the results and call gst_clock_set_calibration() with the values, or some modified version of them.

Since: 1.6

gst_clock_set_master ()

gboolean
gst_clock_set_master (GstClock *clock,
                      GstClock *master);

Set master as the master clock for clock . clock will be automatically calibrated so that gst_clock_get_time() reports the same time as the master clock.

A clock provider that slaves its clock to a master can get the current calibration values with gst_clock_get_calibration().

master can be NULL in which case clock will not be slaved anymore. It will however keep reporting its time adjusted with the last configured rate and time offsets.

gst_clock_get_master ()

GstClock *
gst_clock_get_master (GstClock *clock);

Get the master clock that clock is slaved to or NULL when the clock is not slaved to any master clock.

gst_clock_set_resolution ()

GstClockTime
gst_clock_set_resolution (GstClock *clock,
                          GstClockTime resolution);

Set the accuracy of the clock. Some clocks have the possibility to operate with different accuracy at the expense of more resource usage. There is normally no need to change the default resolution of a clock. The resolution of a clock can only be changed if the clock has the GST_CLOCK_FLAG_CAN_SET_RESOLUTION flag set.

gst_clock_get_resolution ()

GstClockTime
gst_clock_get_resolution (GstClock *clock);

Get the accuracy of the clock. The accuracy of the clock is the granularity of the values returned by gst_clock_get_time().

gst_clock_get_time ()

GstClockTime
gst_clock_get_time (GstClock *clock);

Gets the current time of the given clock. The time is always monotonically increasing and adjusted according to the current offset and rate.

gst_clock_new_single_shot_id ()

GstClockID
gst_clock_new_single_shot_id (GstClock *clock,
                              GstClockTime time);

Get a GstClockID from clock to trigger a single shot notification at the requested time. The single shot id should be unreffed after usage.

Free-function: gst_clock_id_unref

gst_clock_new_periodic_id ()

GstClockID
gst_clock_new_periodic_id (GstClock *clock,
                           GstClockTime start_time,
                           GstClockTime interval);

Get an ID from clock to trigger a periodic notification. The periodic notifications will start at time start_time and will then be fired with the given interval . id should be unreffed after usage.

Free-function: gst_clock_id_unref

gst_clock_single_shot_id_reinit ()

gboolean
gst_clock_single_shot_id_reinit (GstClock *clock,
                                 GstClockID id,
                                 GstClockTime time);

Reinitializes the provided single shot id to the provided time. Does not modify the reference count.

gst_clock_periodic_id_reinit ()

gboolean
gst_clock_periodic_id_reinit (GstClock *clock,
                              GstClockID id,
                              GstClockTime start_time,
                              GstClockTime interval);

Reinitializes the provided periodic id to the provided start time and interval. Does not modify the reference count.

gst_clock_get_internal_time ()

GstClockTime
gst_clock_get_internal_time (GstClock *clock);

Gets the current internal time of the given clock. The time is returned unadjusted for the offset and the rate.

gst_clock_adjust_unlocked ()

GstClockTime
gst_clock_adjust_unlocked (GstClock *clock,
                           GstClockTime internal);

Converts the given internal clock time to the external time, adjusting for the rate and reference time set with gst_clock_set_calibration() and making sure that the returned time is increasing. This function should be called with the clock's OBJECT_LOCK held and is mainly used by clock subclasses.

This function is the reverse of gst_clock_unadjust_unlocked().

gst_clock_unadjust_unlocked ()

GstClockTime
gst_clock_unadjust_unlocked (GstClock *clock,
                             GstClockTime external);

Converts the given external clock time to the internal time of clock , using the rate and reference time set with gst_clock_set_calibration(). This function should be called with the clock's OBJECT_LOCK held and is mainly used by clock subclasses.

This function is the reverse of gst_clock_adjust_unlocked().

gst_clock_adjust_with_calibration ()

GstClockTime
gst_clock_adjust_with_calibration (GstClock *clock,
                                   GstClockTime internal_target,
                                   GstClockTime cinternal,
                                   GstClockTime cexternal,
                                   GstClockTime cnum,
                                   GstClockTime cdenom);

Converts the given internal_target clock time to the external time, using the passed calibration parameters. This function performs the same calculation as gst_clock_adjust_unlocked() when called using the current calibration parameters, but doesn't ensure a monotonically increasing result as gst_clock_adjust_unlocked() does.

Note: The clock parameter is unused and can be NULL

Since: 1.6

gst_clock_unadjust_with_calibration ()

GstClockTime
gst_clock_unadjust_with_calibration (GstClock *clock,
                                     GstClockTime external_target,
                                     GstClockTime cinternal,
                                     GstClockTime cexternal,
                                     GstClockTime cnum,
                                     GstClockTime cdenom);

Converts the given external_target clock time to the internal time, using the passed calibration parameters. This function performs the same calculation as gst_clock_unadjust_unlocked() when called using the current calibration parameters.

Note: The clock parameter is unused and can be NULL

Since: 1.8

gst_clock_get_calibration ()

void
gst_clock_get_calibration (GstClock *clock,
                           GstClockTime *internal,
                           GstClockTime *external,
                           GstClockTime *rate_num,
                           GstClockTime *rate_denom);

Gets the internal rate and reference time of clock . See gst_clock_set_calibration() for more information.

internal , external , rate_num , and rate_denom can be left NULL if the caller is not interested in the values.

MT safe.

gst_clock_set_calibration ()

void
gst_clock_set_calibration (GstClock *clock,
                           GstClockTime internal,
                           GstClockTime external,
                           GstClockTime rate_num,
                           GstClockTime rate_denom);

Adjusts the rate and time of clock . A rate of 1/1 is the normal speed of the clock. Values bigger than 1/1 make the clock go faster.

internal and external are calibration parameters that arrange that gst_clock_get_time() should have been external at internal time internal . This internal time should not be in the future; that is, it should be less than the value of gst_clock_get_internal_time() when this function is called.

Subsequent calls to gst_clock_get_time() will return clock times computed as follows:

1

time = (internal_time - internal) * rate_num / rate_denom + external

This formula is implemented in gst_clock_adjust_unlocked(). Of course, it tries to do the integer arithmetic as precisely as possible.

Note that gst_clock_get_time() always returns increasing values so when you move the clock backwards, gst_clock_get_time() will report the previous value until the clock catches up.

MT safe.

gst_clock_get_timeout ()

GstClockTime
gst_clock_get_timeout (GstClock *clock);

Get the amount of time that master and slave clocks are sampled.

gst_clock_set_timeout ()

void
gst_clock_set_timeout (GstClock *clock,
                       GstClockTime timeout);

Set the amount of time, in nanoseconds, to sample master and slave clocks

gst_clock_wait_for_sync ()

gboolean
gst_clock_wait_for_sync (GstClock *clock,
                         GstClockTime timeout);

Waits until clock is synced for reporting the current time. If timeout is GST_CLOCK_TIME_NONE it will wait forever, otherwise it will time out after timeout nanoseconds.

For asynchronous waiting, the GstClock::synced signal can be used.

This returns immediately with TRUE if GST_CLOCK_FLAG_NEEDS_STARTUP_SYNC is not set on the clock, or if the clock is already synced.

Since: 1.6

gst_clock_is_synced ()

gboolean
gst_clock_is_synced (GstClock *clock);

Checks if the clock is currently synced.

This returns if GST_CLOCK_FLAG_NEEDS_STARTUP_SYNC is not set on the clock.

Since: 1.6

gst_clock_set_synced ()

void
gst_clock_set_synced (GstClock *clock,
                      gboolean synced);

Sets clock to synced and emits the GstClock::synced signal, and wakes up any thread waiting in gst_clock_wait_for_sync().

This function must only be called if GST_CLOCK_FLAG_NEEDS_STARTUP_SYNC is set on the clock, and is intended to be called by subclasses only.

Since: 1.6

gst_clock_id_get_time ()

GstClockTime
gst_clock_id_get_time (GstClockID id);

Get the time of the clock ID

gst_clock_id_wait ()

GstClockReturn
gst_clock_id_wait (GstClockID id,
                   GstClockTimeDiff *jitter);

Perform a blocking wait on id . id should have been created with gst_clock_new_single_shot_id() or gst_clock_new_periodic_id() and should not have been unscheduled with a call to gst_clock_id_unschedule().

If the jitter argument is not NULL and this function returns GST_CLOCK_OK or GST_CLOCK_EARLY, it will contain the difference against the clock and the time of id when this method was called. Positive values indicate how late id was relative to the clock (in which case this function will return GST_CLOCK_EARLY). Negative values indicate how much time was spent waiting on the clock before this function returned.

gst_clock_id_wait_async ()

GstClockReturn
gst_clock_id_wait_async (GstClockID id,
                         GstClockCallback func,
                         gpointer user_data,
                         GDestroyNotify destroy_data);

Register a callback on the given GstClockID id with the given function and user_data. When passing a GstClockID with an invalid time to this function, the callback will be called immediately with a time set to GST_CLOCK_TIME_NONE. The callback will be called when the time of id has been reached.

The callback func can be invoked from any thread, either provided by the core or from a streaming thread. The application should be prepared for this.

gst_clock_id_unschedule ()

void
gst_clock_id_unschedule (GstClockID id);

Cancel an outstanding request with id . This can either be an outstanding async notification or a pending sync notification. After this call, id cannot be used anymore to receive sync or async notifications, you need to create a new GstClockID.

MT safe.

gst_clock_id_compare_func ()

gint
gst_clock_id_compare_func (gconstpointer id1,
                           gconstpointer id2);

Compares the two GstClockID instances. This function can be used as a GCompareFunc when sorting ids.

gst_clock_id_ref ()

GstClockID
gst_clock_id_ref (GstClockID id);

Increase the refcount of given id .

gst_clock_id_unref ()

void
gst_clock_id_unref (GstClockID id);

Unref given id . When the refcount reaches 0 the GstClockID will be freed.

MT safe.

struct GstClock

struct GstClock;

GstClock base structure. The values of this structure are protected for subclasses, use the methods to use the GstClock.

struct GstClockClass

struct GstClockClass {
  GstObjectClass        parent_class;

  /* vtable */
  GstClockTime          (*change_resolution)    (GstClock *clock,
                                                 GstClockTime old_resolution,
                                                 GstClockTime new_resolution);
  GstClockTime          (*get_resolution)       (GstClock *clock);

  GstClockTime          (*get_internal_time)    (GstClock *clock);

  /* waiting on an ID */
  GstClockReturn        (*wait)                 (GstClock *clock, GstClockEntry *entry,
                                                 GstClockTimeDiff *jitter);
  GstClockReturn        (*wait_async)           (GstClock *clock, GstClockEntry *entry);
  void                  (*unschedule)           (GstClock *clock, GstClockEntry *entry);
};

GStreamer clock class. Override the vmethods to implement the clock functionality.

GstClockTime

typedef guint64 GstClockTime;

A datatype to hold a time, measured in nanoseconds.

GstClockTimeDiff

typedef gint64 GstClockTimeDiff;

A datatype to hold a time difference, measured in nanoseconds.

GstClockID

typedef gpointer GstClockID;

A datatype to hold the handle to an outstanding sync or async clock callback.

GST_CLOCK_TIME_NONE

#define GST_CLOCK_TIME_NONE             ((GstClockTime) -1)

Constant to define an undefined clock time.

GST_CLOCK_STIME_NONE

#define GST_CLOCK_STIME_NONE             ((GstClockTimeDiff)G_MININT64)

Constant to define an undefined clock time.

GST_SECOND

#define GST_SECOND  ((GstClockTimeDiff)(G_USEC_PER_SEC * G_GINT64_CONSTANT (1000)))

Constant that defines one GStreamer second.

GST_MSECOND

#define GST_MSECOND ((GstClockTimeDiff)(GST_SECOND / G_GINT64_CONSTANT (1000)))

Constant that defines one GStreamer millisecond.

GST_USECOND

#define GST_USECOND ((GstClockTimeDiff)(GST_SECOND / G_GINT64_CONSTANT (1000000)))

Constant that defines one GStreamer microsecond.

GST_NSECOND

#define GST_NSECOND ((GstClockTimeDiff)(GST_SECOND / G_GINT64_CONSTANT (1000000000)))

Constant that defines one GStreamer nanosecond

struct GstClockEntry

struct GstClockEntry {
  gint                  refcount;
};

All pending timeouts or periodic notifies are converted into an entry. Note that GstClockEntry should be treated as an opaque structure. It must not be extended or allocated using a custom allocator.

enum GstClockEntryType

The type of the clock entry

enum GstClockReturn

The return value of a clock operation.

enum GstClockFlags

The capabilities of this clock

The “timeout” property

  “timeout”                  guint64

The amount of time, in nanoseconds, to sample master and slave clocks.

Flags: Read / Write

Default value: 100000000

The “window-size” property

  “window-size”              gint

The size of the window used to calculate rate and offset.

Flags: Read / Write

Allowed values: [2,1024]

Default value: 32

The “window-threshold” property

  “window-threshold”         gint

The threshold to start calculating rate and offset.

Flags: Read / Write

Allowed values: [2,1024]

Default value: 4

The “synced” signal

void
user_function (GstClock *clock,
               gboolean  synced,
               gpointer  user_data)

Signaled on clocks with GST_CLOCK_FLAG_NEEDS_STARTUP_SYNC set once the clock is synchronized, or when it completely lost synchronization. This signal will not be emitted on clocks without the flag.

This signal will be emitted from an arbitrary thread, most likely not the application's main thread.

Flags: Run Last

Since: 1.6