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GStreamer 0.10 Core Reference Manual | ![]() |
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#include <gst/gst.h> GstClock; GstClockClass; typedef GstClockTime; typedef GstClockTimeDiff; typedef GstClockID; #define GST_CLOCK_TIME_NONE #define GST_CLOCK_TIME_IS_VALID (time) #define GST_SECOND #define GST_MSECOND #define GST_USECOND #define GST_NSECOND #define GST_CLOCK_DIFF (s, e) #define GST_TIMEVAL_TO_TIME (tv) #define GST_TIME_TO_TIMEVAL (t,tv) #define GST_TIMESPEC_TO_TIME (ts) #define GST_TIME_TO_TIMESPEC (t,ts) #define GST_CLOCK_ENTRY_TRACE_NAME GstClockEntry; gboolean (*GstClockCallback) (GstClock *clock, GstClockTime time, GstClockID id, gpointer user_data); enum GstClockEntryType; #define GST_CLOCK_ENTRY (entry) #define GST_CLOCK_ENTRY_CLOCK (entry) #define GST_CLOCK_ENTRY_TYPE (entry) #define GST_CLOCK_ENTRY_TIME (entry) #define GST_CLOCK_ENTRY_INTERVAL (entry) #define GST_CLOCK_ENTRY_STATUS (entry) enum GstClockReturn; enum GstClockFlags; #define GST_CLOCK_FLAGS (clock) #define GST_CLOCK_BROADCAST (clock) #define GST_CLOCK_COND (clock) #define GST_CLOCK_TIMED_WAIT (clock,tv) #define GST_CLOCK_WAIT (clock) gboolean gst_clock_add_observation (GstClock *clock, GstClockTime slave, GstClockTime master, gdouble *r_squared); gboolean gst_clock_set_master (GstClock *clock, GstClock *master); GstClock* gst_clock_get_master (GstClock *clock); GstClockTime gst_clock_set_resolution (GstClock *clock, GstClockTime resolution); GstClockTime gst_clock_get_resolution (GstClock *clock); GstClockTime gst_clock_get_time (GstClock *clock); GstClockID gst_clock_new_single_shot_id (GstClock *clock, GstClockTime time); GstClockID gst_clock_new_periodic_id (GstClock *clock, GstClockTime start_time, GstClockTime interval); GstClockTime gst_clock_get_internal_time (GstClock *clock); GstClockTime gst_clock_adjust_unlocked (GstClock *clock, GstClockTime internal); void gst_clock_get_calibration (GstClock *clock, GstClockTime *internal, GstClockTime *external, GstClockTime *rate_num, GstClockTime *rate_denom); void gst_clock_set_calibration (GstClock *clock, GstClockTime internal, GstClockTime external, GstClockTime rate_num, GstClockTime rate_denom); GstClockTime gst_clock_id_get_time (GstClockID id); GstClockReturn gst_clock_id_wait (GstClockID id, GstClockTimeDiff *jitter); GstClockReturn gst_clock_id_wait_async (GstClockID id, GstClockCallback func, gpointer user_data); void gst_clock_id_unschedule (GstClockID id); gint gst_clock_id_compare_func (gconstpointer id1, gconstpointer id2); GstClockID gst_clock_id_ref (GstClockID id); void gst_clock_id_unref (GstClockID id); #define GST_TYPE_CLOCK_TIME
"stats" gboolean : Read / Write "timeout" guint64 : Read / Write "window-size" gint : Read / Write "window-threshold" gint : Read / Write
GStreamer uses a global clock to synchronize the plugins in a pipeline. Different clock implementations are possible by implementing this abstract base class.
The GstClock returns a monotonically increasing time with the method
gst_clock_get_time()
. Its accuracy and base time depend on the specific
clock implementation but time is always expressed in nanoseconds. Since the
baseline of the clock is undefined, the clock time returned is not
meaningful in itself, what matters are the deltas between two clock times.
The time returned by a clock is called the absolute time.
The pipeline uses the clock to calculate the stream time. Usually all renderers synchronize to the global clock using the buffer timestamps, the newsegment events and the element's base time, see GstPipeline.
A clock implementation can support periodic and single shot clock notifications both synchronous and asynchronous.
One first needs to create a GstClockID for the periodic or single shot
notification using gst_clock_new_single_shot_id()
or
gst_clock_new_periodic_id()
.
To perform a blocking wait for the specific time of the GstClockID use the
gst_clock_id_wait()
. To receive a callback when the specific time is reached
in the clock use gst_clock_id_wait_async()
. Both these calls can be
interrupted with the gst_clock_id_unschedule()
call. If the blocking wait is
unscheduled a return value of GST_CLOCK_UNSCHEDULED is returned.
Periodic callbacks scheduled async will be repeadedly called automatically
until it is unscheduled. To schedule a sync periodic callback,
gst_clock_id_wait()
should be called repeadedly.
The async callbacks can happen from any thread, either provided by the core or from a streaming thread. The application should be prepared for this.
A GstClockID that has been unscheduled cannot be used again for any wait
operation, a new GstClockID should be created and the old unscheduled one
should be destroyed wirth gst_clock_id_unref()
.
It is possible to perform a blocking wait on the same GstClockID from multiple threads. However, registering the same GstClockID for multiple async notifications is not possible, the callback will only be called for the thread registering the entry last.
None of the wait operations unref the GstClockID, the owner is responsible for unreffing the ids itself. This holds for both periodic and single shot notifications. The reason being that the owner of the GstClockID has to keep a handle to the GstClockID to unblock the wait on FLUSHING events or state changes and if the entry would be unreffed automatically, the handle might become invalid without any notification.
These clock operations do not operate on the stream time, so the callbacks will also occur when not in PLAYING state as if the clock just keeps on running. Some clocks however do not progress when the element that provided the clock is not PLAYING.
When a clock has the GST_CLOCK_FLAG_CAN_SET_MASTER flag set, it can be
slaved to another GstClock with the gst_clock_set_master()
. The clock will
then automatically be synchronized to this master clock by repeadedly
sampling the master clock and the slave clock and recalibrating the slave
clock with gst_clock_set_calibration()
. This feature is mostly useful for
plugins that have an internal clock but must operate with another clock
selected by the GstPipeline. They can track the offset and rate difference
of their internal clock relative to the master clock by using the
gst_clock_get_calibration()
function.
The master/slave synchronisation can be tuned with the "timeout", "window-size" and "window-threshold" properties. The "timeout" property defines the interval to sample the master clock and run the calibration functions. "window-size" defines the number of samples to use when calibrating and "window-threshold" defines the minimum number of samples before the calibration is performed.
Last reviewed on 2006-08-11 (0.10.10)
typedef struct _GstClock GstClock;
GstClock base structure. The values of this structure are protected for subclasses, use the methods to use the GstClock.
typedef struct { 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); GstClockReturn (*wait_async) (GstClock *clock, GstClockEntry *entry); void (*unschedule) (GstClock *clock, GstClockEntry *entry); /* ABI added to replace the deprecated wait */ GstClockReturn (*wait_jitter) (GstClock *clock, GstClockEntry *entry, GstClockTimeDiff *jitter); } GstClockClass;
GStreamer clock class. Override the vmethods to implement the clock functionality.
parent_class
;GstObjectClassparent_class
the parent class structure
the parent class structure
change_resolution
()change_resolution
change the resolution of the clock. Not all values might
be acceptable. The new resolution should be returned.
change the resolution of the clock. Not all values might
be acceptable. The new resolution should be returned.
get_resolution
()get_resolution
get the resolution of the clock.
get the resolution of the clock.
get_internal_time
()get_internal_time
get the internal unadjusted time of the clock.
get the internal unadjusted time of the clock.
wait
()wait
perform a blocking wait for the given GstClockEntry. Deprecated,
implement wait_jitter
instead.
perform a blocking wait for the given GstClockEntry. Deprecated,
implement wait_jitter
instead.
wait_jitter
wait_async
()wait_async
perform an asynchronous wait for the given GstClockEntry.
perform an asynchronous wait for the given GstClockEntry.
unschedule
()unschedule
unblock a blocking or async wait operation.
unblock a blocking or async wait operation.
wait_jitter
()wait_jitter
perform a blocking wait on the given GstClockEntry and return
the jitter. (Since: 0.10.10)
perform a blocking wait on the given GstClockEntry and return
the jitter. (Since: 0.10.10)
GstObjectClass parent_class ; |
the parent class structure |
change_resolution () |
change the resolution of the clock. Not all values might be acceptable. The new resolution should be returned. |
get_resolution () |
get the resolution of the clock. |
get_internal_time () |
get the internal unadjusted time of the clock. |
wait () |
perform a blocking wait for the given GstClockEntry. Deprecated,
implement wait_jitter instead.
|
wait_async () |
perform an asynchronous wait for the given GstClockEntry. |
unschedule () |
unblock a blocking or async wait operation. |
wait_jitter () |
perform a blocking wait on the given GstClockEntry and return the jitter. (Since: 0.10.10) |
typedef gint64 GstClockTimeDiff;
A datatype to hold a timedifference, measured in nanoseconds.
typedef gpointer GstClockID;
A datatype to hold the handle to an outstanding sync or async clock callback.
#define GST_CLOCK_TIME_NONE ((GstClockTime) -1)
Constant to define an undefined clock time.
#define GST_CLOCK_TIME_IS_VALID(time) (((GstClockTime)(time)) != GST_CLOCK_TIME_NONE)
Tests if a given GstClockTime represents a valid defined time.
time
:time
clock time to validate
clock time to validate
time : |
clock time to validate |
#define GST_SECOND (G_USEC_PER_SEC * G_GINT64_CONSTANT (1000))
Constant that defines one GStreamer second.
#define GST_MSECOND (GST_SECOND / G_GINT64_CONSTANT (1000))
Constant that defines one GStreamer millisecond.
#define GST_USECOND (GST_SECOND / G_GINT64_CONSTANT (1000000))
Constant that defines one GStreamer microsecond.
#define GST_NSECOND (GST_SECOND / G_GINT64_CONSTANT (1000000000))
Constant that defines one GStreamer nanosecond
#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
.
s
:s
the first time
the first time
e
:e
the second time
the second time
s : |
the first time |
e : |
the second time |
#define GST_TIMEVAL_TO_TIME(tv) ((tv).tv_sec * GST_SECOND + (tv).tv_usec * GST_USECOND)
Convert a GTimeVal to a GstClockTime.
tv
:tv
the timeval to convert
the timeval to convert
tv : |
the timeval to convert |
#define GST_TIME_TO_TIMEVAL(t,tv)
Note: on 32-bit systems, a timeval has a range of only 2^32 - 1 seconds, which is about 68 years. Expect trouble if you want to schedule stuff in your pipeline for 2038.
Convert a GstClockTime to a GTimeVal
t
:t
The GstClockTime to convert
The GstClockTime to convert
tv
:tv
The target timeval
The target timeval
t : |
The GstClockTime to convert |
tv : |
The target timeval |
#define GST_TIMESPEC_TO_TIME(ts) ((ts).tv_sec * GST_SECOND + (ts).tv_nsec * GST_NSECOND)
Convert a struct timespec (see man pselect) to a GstClockTime.
ts
:ts
the timespec to convert
the timespec to convert
ts : |
the timespec to convert |
#define GST_TIME_TO_TIMESPEC(t,ts)
Convert a GstClockTime to a struct timespec (see man pselect)
t
:t
The GstClockTime to convert
The GstClockTime to convert
ts
:ts
The target timespec
The target timespec
t : |
The GstClockTime to convert |
ts : |
The target timespec |
#define GST_CLOCK_ENTRY_TRACE_NAME "GstClockEntry"
The name used for tracing clock entry allocations.
typedef struct { gint refcount; } GstClockEntry;
All pending timeouts or periodic notifies are converted into an entry.
refcount
;gintrefcount
reference counter (read-only)
reference counter (read-only)
gint refcount ; |
reference counter (read-only) |
gboolean (*GstClockCallback) (GstClock *clock, GstClockTime time, GstClockID id, gpointer user_data);
The function prototype of the callback.
clock
:clock
The clock that triggered the callback
The clock that triggered the callback
time
:time
The time it was triggered
The time it was triggered
id
:id
The GstClockID that expired
The GstClockID that expired
GstClockIDGstClockIDuser_data
:user_data
user data passed in the gst_clock_id_wait_async()
function
user data passed in the gst_clock_id_wait_async()
function
gst_clock_id_wait_async()
gst_clock_id_wait_async()
Returns :Returns TRUE
or FALSE
(currently unused)
TRUE
or FALSE
(currently unused)
TRUE
TRUE
FALSE
FALSE
clock : |
The clock that triggered the callback |
time : |
The time it was triggered |
id : |
The GstClockID that expired |
user_data : |
user data passed in the gst_clock_id_wait_async() function
|
Returns : | TRUE or FALSE (currently unused)
|
typedef enum { GST_CLOCK_ENTRY_SINGLE, GST_CLOCK_ENTRY_PERIODIC } GstClockEntryType;
The type of the clock entry
#define GST_CLOCK_ENTRY(entry) ((GstClockEntry *)(entry))
Cast to a clock entry
entry
:entry
the entry to cast
the entry to cast
entry : |
the entry to cast |
#define GST_CLOCK_ENTRY_CLOCK(entry) ((entry)->clock)
Get the owner clock of the entry
entry
:entry
the entry to query
the entry to query
entry : |
the entry to query |
#define GST_CLOCK_ENTRY_TYPE(entry) ((entry)->type)
Get the type of the clock entry
entry
:entry
the entry to query
the entry to query
entry : |
the entry to query |
#define GST_CLOCK_ENTRY_TIME(entry) ((entry)->time)
Get the requested time of this entry
entry
:entry
the entry to query
the entry to query
entry : |
the entry to query |
#define GST_CLOCK_ENTRY_INTERVAL(entry) ((entry)->interval)
Get the interval of this periodic entry
entry
:entry
the entry to query
the entry to query
entry : |
the entry to query |
#define GST_CLOCK_ENTRY_STATUS(entry) ((entry)->status)
The status of the entry
entry
:entry
the entry to query
the entry to query
entry : |
the entry to query |
typedef enum { GST_CLOCK_OK = 0, GST_CLOCK_EARLY = 1, GST_CLOCK_UNSCHEDULED = 2, GST_CLOCK_BUSY = 3, GST_CLOCK_BADTIME = 4, GST_CLOCK_ERROR = 5, GST_CLOCK_UNSUPPORTED = 6 } GstClockReturn;
The return value of a clock operation.
GST_CLOCK_OK
GST_CLOCK_OK
The operation succeded.
The operation succeded.
GST_CLOCK_EARLY
GST_CLOCK_EARLY
The operation was scheduled too late.
The operation was scheduled too late.
GST_CLOCK_UNSCHEDULED
GST_CLOCK_UNSCHEDULED
The clockID was unscheduled
The clockID was unscheduled
GST_CLOCK_BUSY
GST_CLOCK_BUSY
The ClockID is busy
The ClockID is busy
GST_CLOCK_BADTIME
GST_CLOCK_BADTIME
A bad time was provided to a function.
A bad time was provided to a function.
GST_CLOCK_ERROR
GST_CLOCK_ERROR
An error occured
An error occured
GST_CLOCK_UNSUPPORTED
GST_CLOCK_UNSUPPORTED
Operation is not supported
Operation is not supported
typedef enum { GST_CLOCK_FLAG_CAN_DO_SINGLE_SYNC = (GST_OBJECT_FLAG_LAST << 0), GST_CLOCK_FLAG_CAN_DO_SINGLE_ASYNC = (GST_OBJECT_FLAG_LAST << 1), GST_CLOCK_FLAG_CAN_DO_PERIODIC_SYNC = (GST_OBJECT_FLAG_LAST << 2), GST_CLOCK_FLAG_CAN_DO_PERIODIC_ASYNC = (GST_OBJECT_FLAG_LAST << 3), GST_CLOCK_FLAG_CAN_SET_RESOLUTION = (GST_OBJECT_FLAG_LAST << 4), GST_CLOCK_FLAG_CAN_SET_MASTER = (GST_OBJECT_FLAG_LAST << 5), /* padding */ GST_CLOCK_FLAG_LAST = (GST_OBJECT_FLAG_LAST << 8) } GstClockFlags;
The capabilities of this clock
GST_CLOCK_FLAG_CAN_DO_SINGLE_SYNC
GST_CLOCK_FLAG_CAN_DO_SINGLE_SYNC
clock can do a single sync timeout request
clock can do a single sync timeout request
GST_CLOCK_FLAG_CAN_DO_SINGLE_ASYNC
GST_CLOCK_FLAG_CAN_DO_SINGLE_ASYNC
clock can do a single async timeout request
clock can do a single async timeout request
GST_CLOCK_FLAG_CAN_DO_PERIODIC_SYNC
GST_CLOCK_FLAG_CAN_DO_PERIODIC_SYNC
clock can do sync periodic timeout requests
clock can do sync periodic timeout requests
GST_CLOCK_FLAG_CAN_DO_PERIODIC_ASYNC
GST_CLOCK_FLAG_CAN_DO_PERIODIC_ASYNC
clock can do async periodic timeout callbacks
clock can do async periodic timeout callbacks
GST_CLOCK_FLAG_CAN_SET_RESOLUTION
GST_CLOCK_FLAG_CAN_SET_RESOLUTION
clock's resolution can be changed
clock's resolution can be changed
GST_CLOCK_FLAG_CAN_SET_MASTER
GST_CLOCK_FLAG_CAN_SET_MASTER
clock can be slaved to a master clock
clock can be slaved to a master clock
GST_CLOCK_FLAG_LAST
GST_CLOCK_FLAG_LAST
subclasses can add additional flags starting from this flag
subclasses can add additional flags starting from this flag
#define GST_CLOCK_FLAGS(clock) (GST_CLOCK(clock)->flags)
Gets the GstClockFlags clock flags.
clock
:clock
the clock to query
the clock to query
clock : |
the clock to query |
#define GST_CLOCK_BROADCAST(clock) g_cond_broadcast(GST_CLOCK_COND(clock))
Signal that the entries in the clock have changed.
clock
:clock
the clock to broadcast
the clock to broadcast
clock : |
the clock to broadcast |
#define GST_CLOCK_COND(clock) (GST_CLOCK_CAST(clock)->entries_changed)
Gets the GCond that gets signaled when the entries of the clock changed.
clock
:clock
the clock to query
the clock to query
clock : |
the clock to query |
#define GST_CLOCK_TIMED_WAIT(clock,tv) g_cond_timed_wait(GST_CLOCK_COND(clock),GST_OBJECT_GET_LOCK(clock),tv)
Wait on the clock until the entries changed or the specified timeout occured.
clock
:clock
the clock to wait on
the clock to wait on
tv
:tv
a GTimeVal to wait.
a GTimeVal to wait.
clock : |
the clock to wait on |
tv : |
a GTimeVal to wait. |
#define GST_CLOCK_WAIT(clock) g_cond_wait(GST_CLOCK_COND(clock),GST_OBJECT_GET_LOCK(clock))
Wait on the clock until the entries changed.
clock
:clock
the clock to wait on
the clock to wait on
clock : |
the clock to wait on |
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 interpollation. 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.
clock
:clock
a GstClock
a GstClock
GstClockGstClockslave
:slave
a time on the slave
a time on the slave
master
:master
a time on the master
a time on the master
r_squared
:r_squared
a pointer to hold the result
a pointer to hold the result
Returns :Returns TRUE if enough observations were added to run the
regression algorithm.
MT safe.
TRUE if enough observations were added to run the
regression algorithm.
MT safe.
clock : |
a GstClock |
slave : |
a time on the slave |
master : |
a time on the master |
r_squared : |
a pointer to hold the result |
Returns : | TRUE if enough observations were added to run the regression algorithm. MT safe. |
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.
clock
:clock
a GstClock
a GstClock
GstClockGstClockmaster
:master
a master GstClock
a master GstClock
GstClockGstClockReturns :Returns TRUE if the clock is capable of being slaved to a master clock.
Trying to set a master on a clock without the
GST_CLOCK_FLAG_CAN_SET_MASTER flag will make this function return FALSE.
MT safe.
TRUE if the clock is capable of being slaved to a master clock.
Trying to set a master on a clock without the
GST_CLOCK_FLAG_CAN_SET_MASTER flag will make this function return FALSE.
MT safe.
clock : |
a GstClock |
master : |
a master GstClock |
Returns : | TRUE if the clock is capable of being slaved to a master clock. Trying to set a master on a clock without the GST_CLOCK_FLAG_CAN_SET_MASTER flag will make this function return FALSE. MT safe. |
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.
clock
:clock
a GstClock
a GstClock
GstClockGstClockReturns :Returns a master GstClock or NULL when this clock is not slaved to a master
clock. Unref after usage.
MT safe.
a master GstClock or NULL when this clock is not slaved to a master
clock. Unref after usage.
MT safe.
GstClockGstClock
clock : |
a GstClock |
Returns : | a master GstClock or NULL when this clock is not slaved to a master clock. Unref after usage. MT safe. |
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.
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()
.
clock
:clock
a GstClock
a GstClock
GstClockGstClockReturns :Returns the resolution of the clock in units of GstClockTime.
MT safe.
the resolution of the clock in units of GstClockTime.
MT safe.
GstClockTimeGstClockTime
clock : |
a GstClock |
Returns : | the resolution of the clock in units of GstClockTime. MT safe. |
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.
clock
:clock
a GstClock to query
a GstClock to query
GstClockGstClockReturns :Returns the time of the clock. Or GST_CLOCK_TIME_NONE when
giving wrong input.
MT safe.
the time of the clock. Or GST_CLOCK_TIME_NONE when
giving wrong input.
MT safe.
clock : |
a GstClock to query |
Returns : | the time of the clock. Or GST_CLOCK_TIME_NONE when giving wrong input. MT safe. |
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.
clock
:clock
The GstClockID to get a single shot notification from
The GstClockID to get a single shot notification from
GstClockIDGstClockIDtime
:time
the requested time
the requested time
Returns :Returns A GstClockID that can be used to request the time notification.
MT safe.
A GstClockID that can be used to request the time notification.
MT safe.
GstClockIDGstClockID
clock : |
The GstClockID to get a single shot notification from |
time : |
the requested time |
Returns : | A GstClockID that can be used to request the time notification. MT safe. |
GstClockID gst_clock_new_periodic_id (GstClock *clock, GstClockTime start_time, GstClockTime interval);
Get an ID from clock
to trigger a periodic notification.
The periodeic notifications will be start at time start_time and
will then be fired with the given interval. id
should be unreffed
after usage.
clock
:clock
The GstClockID to get a periodic notification id from
The GstClockID to get a periodic notification id from
GstClockIDGstClockIDstart_time
:start_time
the requested start time
the requested start time
interval
:interval
the requested interval
the requested interval
Returns :Returns A GstClockID that can be used to request the time notification.
MT safe.
A GstClockID that can be used to request the time notification.
MT safe.
GstClockIDGstClockID
clock : |
The GstClockID to get a periodic notification id from |
start_time : |
the requested start time |
interval : |
the requested interval |
Returns : | A GstClockID that can be used to request the time notification. MT safe. |
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.
clock
:clock
a GstClock to query
a GstClock to query
GstClockGstClockReturns :Returns the internal time of the clock. Or GST_CLOCK_TIME_NONE when
giving wrong input.
MT safe.
the internal time of the clock. Or GST_CLOCK_TIME_NONE when
giving wrong input.
MT safe.
clock : |
a GstClock to query |
Returns : | the internal time of the clock. Or GST_CLOCK_TIME_NONE when giving wrong input. MT safe. |
GstClockTime gst_clock_adjust_unlocked (GstClock *clock, GstClockTime internal);
Converts the given internal
clock time to the real 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.
clock
:clock
a GstClock to use
a GstClock to use
GstClockGstClockinternal
:internal
a clock time
a clock time
Returns :Returns the converted time of the clock.
MT safe.
the converted time of the clock.
MT safe.
clock : |
a GstClock to use |
internal : |
a clock time |
Returns : | the converted time of the clock. MT safe. |
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.
clock
:clock
a GstClock
a GstClock
GstClockGstClockinternal
:internal
a location to store the internal time
a location to store the internal time
external
:external
a location to store the external time
a location to store the external time
rate_num
:rate_num
a location to store the rate numerator
a location to store the rate numerator
rate_denom
:rate_denom
a location to store the rate denominator
a location to store the rate denominator
clock : |
a GstClock |
internal : |
a location to store the internal time |
external : |
a location to store the external time |
rate_num : |
a location to store the rate numerator |
rate_denom : |
a location to store the rate denominator |
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:
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.
clock
:clock
a GstClock to calibrate
a GstClock to calibrate
GstClockGstClockinternal
:internal
a reference internal time
a reference internal time
external
:external
a reference external time
a reference external time
rate_num
:rate_num
the numerator of the rate of the clock relative to its
internal time
the numerator of the rate of the clock relative to its
internal time
rate_denom
:rate_denom
the denominator of the rate of the clock
the denominator of the rate of the clock
clock : |
a GstClock to calibrate |
internal : |
a reference internal time |
external : |
a reference external time |
rate_num : |
the numerator of the rate of the clock relative to its internal time |
rate_denom : |
the denominator of the rate of the clock |
GstClockTime gst_clock_id_get_time (GstClockID id);
Get the time of the clock ID
id
:id
The GstClockID to query
The GstClockID to query
GstClockIDGstClockIDReturns :Returns the time of the given clock id.
MT safe.
the time of the given clock id.
MT safe.
id : |
The GstClockID to query |
Returns : | the time of the given clock id. MT safe. |
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.
id
:id
The GstClockID to wait on
The GstClockID to wait on
GstClockIDGstClockIDjitter
:jitter
A pointer that will contain the jitter, can be NULL.
A pointer that will contain the jitter, can be NULL.
Returns :Returns the result of the blocking wait. GST_CLOCK_EARLY will be returned
if the current clock time is past the time of id
, GST_CLOCK_OK if
id
was scheduled in time. GST_CLOCK_UNSCHEDULED if id
was
unscheduled with gst_clock_id_unschedule()
.
MT safe.
the result of the blocking wait. GST_CLOCK_EARLY will be returned
if the current clock time is past the time of id
, GST_CLOCK_OK if
id
was scheduled in time. GST_CLOCK_UNSCHEDULED if id
was
unscheduled with gst_clock_id_unschedule()
.
MT safe.
GST_CLOCK_EARLYGST_CLOCK_EARLYid
GST_CLOCK_OKGST_CLOCK_OKid
GST_CLOCK_UNSCHEDULEDGST_CLOCK_UNSCHEDULEDid
gst_clock_id_unschedule()
gst_clock_id_unschedule()
id : |
The GstClockID to wait on |
jitter : |
A pointer that will contain the jitter, can be NULL. |
Returns : | the result of the blocking wait. GST_CLOCK_EARLY will be returned
if the current clock time is past the time of id , GST_CLOCK_OK if
id was scheduled in time. GST_CLOCK_UNSCHEDULED if id was
unscheduled with gst_clock_id_unschedule() .
MT safe.
|
GstClockReturn gst_clock_id_wait_async (GstClockID id, GstClockCallback func, gpointer user_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 immediatly
with a time set to GST_CLOCK_TIME_NONE. The callback will
be called when the time of id
has been reached.
id
:id
a GstClockID to wait on
a GstClockID to wait on
GstClockIDGstClockIDfunc
:func
The callback function
The callback function
user_data
:user_data
User data passed in the calback
User data passed in the calback
Returns :Returns the result of the non blocking wait.
MT safe.
the result of the non blocking wait.
MT safe.
id : |
a GstClockID to wait on |
func : |
The callback function |
user_data : |
User data passed in the calback |
Returns : | the result of the non blocking wait. MT safe. |
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.
id
:id
The id to unschedule
The id to unschedule
id : |
The id to unschedule |
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.
id1
:id1
A GstClockID
A GstClockID
GstClockIDGstClockIDid2
:id2
A GstClockID to compare with
A GstClockID to compare with
GstClockIDGstClockIDReturns :Returns negative value if a < b; zero if a = b; positive value if a > b
MT safe.
negative value if a < b; zero if a = b; positive value if a > b
MT safe.
id1 : |
A GstClockID |
id2 : |
A GstClockID to compare with |
Returns : | negative value if a < b; zero if a = b; positive value if a > b MT safe. |
GstClockID gst_clock_id_ref (GstClockID id);
Increase the refcount of given id
.
id
:id
The GstClockID to ref
The GstClockID to ref
GstClockIDGstClockIDReturns :Returns The same GstClockID with increased refcount.
MT safe.
The same GstClockID with increased refcount.
MT safe.
GstClockIDGstClockID
id : |
The GstClockID to ref |
Returns : | The same GstClockID with increased refcount. MT safe. |
void gst_clock_id_unref (GstClockID id);
Unref given id
. When the refcount reaches 0 the
GstClockID will be freed.
MT safe.
id
:id
The GstClockID to unref
The GstClockID to unref
GstClockIDGstClockID
id : |
The GstClockID to unref |
stats
" property"stats" gboolean : Read / Write
Enable clock stats (unimplemented).
Default value: FALSE
timeout
" property"timeout" guint64 : Read / Write
The amount of time, in nanoseconds, to sample master and slave clocks.
Default value: 100000000
window-size
" property"window-size" gint : Read / Write
The size of the window used to calculate rate and offset.
Allowed values: [2,1024]
Default value: 32