Commit 99a61247 authored by Wim Taymans's avatar Wim Taymans

gst/gstclock.*: Review docs.

Original commit message from CVS:
* gst/gstclock.c: (gst_clock_entry_new),
(gst_clock_id_compare_func), (gst_clock_id_wait),
(gst_clock_id_wait_async), (gst_clock_id_unschedule),
(gst_clock_init), (gst_clock_get_internal_time),
(gst_clock_set_master), (do_linear_regression),
(gst_clock_add_observation), (gst_clock_set_property):
* gst/gstclock.h:
Review docs.
Small cleanups.
Fix a possible segfault when the window-size is made smaller.
Calculate jitter before performing the clock wait. Ideally
the clock implementation should calculate jitter but we need
API breakage for that.
* gst/gstsystemclock.c: (gst_system_clock_init):
Docs review.
* libs/gst/base/gstbasesink.c: (gst_base_sink_do_sync):
Remove leftover else
* tests/check/gst/gstsystemclock.c: (GST_START_TEST),
(gst_systemclock_suite):
Added check to test GST_CLOCK_DIFF.
parent b53dc49d
2006-03-09 Wim Taymans <wim@fluendo.com>
* gst/gstclock.c: (gst_clock_entry_new),
(gst_clock_id_compare_func), (gst_clock_id_wait),
(gst_clock_id_wait_async), (gst_clock_id_unschedule),
(gst_clock_init), (gst_clock_get_internal_time),
(gst_clock_set_master), (do_linear_regression),
(gst_clock_add_observation), (gst_clock_set_property):
* gst/gstclock.h:
Review docs.
Small cleanups.
Fix a possible segfault when the window-size is made smaller.
Calculate jitter before performing the clock wait. Ideally
the clock implementation should calculate jitter but we need
API breakage for that.
* gst/gstsystemclock.c: (gst_system_clock_init):
Docs review.
* libs/gst/base/gstbasesink.c: (gst_base_sink_do_sync):
Remove leftover else
* tests/check/gst/gstsystemclock.c: (GST_START_TEST),
(gst_systemclock_suite):
Added check to test GST_CLOCK_DIFF.
2006-03-09 Tim-Philipp Müller <tim at centricular dot net>
* libs/gst/base/gsttypefindhelper.c: (helper_find_get_length),
......
......@@ -31,17 +31,15 @@
* base class.
*
* The #GstClock returns a monotonically increasing time with the method
* gst_clock_get_time(). Its accuracy and base time depends on the specific
* clock implementation but time is always expessed in nanoseconds. Since the
* 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 pipeline uses the clock to calculate the stream time. Usually all
* 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.
*
* The time of the clock in itself is not very useful for an application.
*
* A clock implementation can support periodic and single shot clock
* notifications both synchronous and asynchronous.
*
......@@ -56,24 +54,27 @@
* 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 an async periodic callback,
* 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.
* 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 once.
* 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 we unref it automatically, the handle might be invalid.
* 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
......@@ -88,9 +89,16 @@
* 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.
* 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 2005-10-28 (0.9.4)
* Last reviewed on 2006-03-09 (0.10.4)
*/
#include <time.h>
......@@ -145,7 +153,9 @@ gst_clock_entry_new (GstClock * clock, GstClockTime time,
{
GstClockEntry *entry;
entry = g_malloc0 (sizeof (GstClockEntry));
/* FIXME, use g_slice, we do this a lot and potentially from
* different threads. */
entry = g_new0 (GstClockEntry, 1);
#ifndef GST_DISABLE_TRACE
gst_alloc_trace_new (_gst_clock_entry_trace, entry);
#endif
......@@ -164,9 +174,9 @@ gst_clock_entry_new (GstClock * clock, GstClockTime time,
/**
* gst_clock_id_ref:
* @id: The clockid to ref
* @id: The #GstClockID to ref
*
* Increase the refcount of the given clockid.
* Increase the refcount of given @id.
*
* Returns: The same #GstClockID with increased refcount.
*
......@@ -197,9 +207,9 @@ _gst_clock_id_free (GstClockID id)
/**
* gst_clock_id_unref:
* @id: The clockid to unref
* @id: The #GstClockID to unref
*
* Unref the given clockid. When the refcount reaches 0 the
* Unref given @id. When the refcount reaches 0 the
* #GstClockID will be freed.
*
* MT safe.
......@@ -220,14 +230,14 @@ gst_clock_id_unref (GstClockID id)
/**
* gst_clock_new_single_shot_id
* @clock: The clockid to get a single shot notification from
* @clock: The #GstClockID to get a single shot notification from
* @time: the requested time
*
* Get an ID from the given clock to trigger a single shot
* Get a #GstClockID from @clock to trigger a single shot
* notification at the requested time. The single shot id should be
* unreffed after usage.
*
* Returns: An id that can be used to request the time notification.
* Returns: A #GstClockID that can be used to request the time notification.
*
* MT safe.
*/
......@@ -242,16 +252,16 @@ gst_clock_new_single_shot_id (GstClock * clock, GstClockTime time)
/**
* gst_clock_new_periodic_id
* @clock: The clockid to get a periodic notification id from
* @clock: The #GstClockID to get a periodic notification id from
* @start_time: the requested start time
* @interval: the requested interval
*
* Get an ID from the given clock to trigger a periodic notification.
* 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. The id should be unreffed
* will then be fired with the given interval. @id should be unreffed
* after usage.
*
* Returns: An id that can be used to request the time notification.
* Returns: A #GstClockID that can be used to request the time notification.
*
* MT safe.
*/
......@@ -269,10 +279,10 @@ gst_clock_new_periodic_id (GstClock * clock, GstClockTime start_time,
/**
* gst_clock_id_compare_func
* @id1: A clockid
* @id2: A clockid to compare with
* @id1: A #GstClockID
* @id2: A #GstClockID to compare with
*
* Compares the two GstClockID instances. This function can be used
* Compares the two #GstClockID instances. This function can be used
* as a GCompareFunc when sorting ids.
*
* Returns: negative value if a < b; zero if a = b; positive value if a > b
......@@ -293,13 +303,12 @@ gst_clock_id_compare_func (gconstpointer id1, gconstpointer id2)
if (GST_CLOCK_ENTRY_TIME (entry1) < GST_CLOCK_ENTRY_TIME (entry2)) {
return -1;
}
return entry1 - entry2;
return 0;
}
/**
* gst_clock_id_get_time
* @id: The clockid to query
* @id: The #GstClockID to query
*
* Get the time of the clock ID
*
......@@ -318,13 +327,25 @@ gst_clock_id_get_time (GstClockID id)
/**
* gst_clock_id_wait
* @id: The clockid to wait on
* @jitter: A pointer that will contain the jitter
*
* Perform a blocking wait on the given ID. The jitter arg can be
* NULL.
*
* Returns: the result of the blocking wait.
* @id: The #GstClockID to wait on
* @jitter: A pointer that will contain the jitter, can be NULL.
*
* 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. Negative values means @id was scheduled too late (and this
* function will return #GST_CLOCK_EARLY). Positive values indicate how
* early @id was scheduled.
*
* 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.
*/
......@@ -344,37 +365,39 @@ gst_clock_id_wait (GstClockID id, GstClockTimeDiff * jitter)
clock = GST_CLOCK_ENTRY_CLOCK (entry);
/* can't sync on invalid times */
if (G_UNLIKELY (!GST_CLOCK_TIME_IS_VALID (requested)))
goto invalid_time;
/* a previously unscheduled entry cannot be scheduled again */
if (G_UNLIKELY (entry->status == GST_CLOCK_UNSCHEDULED))
goto unscheduled;
cclass = GST_CLOCK_GET_CLASS (clock);
if (G_LIKELY (cclass->wait)) {
if (G_UNLIKELY (cclass->wait == NULL))
goto not_supported;
GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, clock, "waiting on clock entry %p",
id);
res = cclass->wait (clock, entry);
GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, clock,
"done waiting entry %p, res: %d", id, res);
if (jitter) {
GstClockTime now = gst_clock_get_time (clock);
*jitter = now - requested;
}
if (entry->type == GST_CLOCK_ENTRY_PERIODIC) {
entry->time += entry->interval;
}
if (clock->stats) {
gst_clock_update_stats (clock);
}
} else {
res = GST_CLOCK_UNSUPPORTED;
GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, clock, "waiting on clock entry %p", id);
/* jitter is the diff against the clock when this entry is scheduled */
if (jitter) {
GstClockTime now = gst_clock_get_time (clock);
*jitter = GST_CLOCK_DIFF (requested, now);
}
res = cclass->wait (clock, entry);
GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, clock,
"done waiting entry %p, res: %d", id, res);
if (entry->type == GST_CLOCK_ENTRY_PERIODIC) {
entry->time += entry->interval;
}
if (clock->stats)
gst_clock_update_stats (clock);
return res;
/* ERRORS */
......@@ -390,6 +413,11 @@ unscheduled:
"entry was unscheduled return _UNSCHEDULED");
return GST_CLOCK_UNSCHEDULED;
}
not_supported:
{
GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, clock, "clock wait is not supported");
return GST_CLOCK_UNSUPPORTED;
}
}
/**
......@@ -398,11 +426,11 @@ unscheduled:
* @func: The callback function
* @user_data: User data passed in the calback
*
* Register a callback on the given clockid with the given
* function and user_data. When passing an id with an invalid
* 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 the id has been reached.
* be called when the time of @id has been reached.
*
* Returns: the result of the non blocking wait.
*
......@@ -425,22 +453,24 @@ gst_clock_id_wait_async (GstClockID id,
requested = GST_CLOCK_ENTRY_TIME (entry);
clock = GST_CLOCK_ENTRY_CLOCK (entry);
/* can't sync on invalid times */
if (G_UNLIKELY (!GST_CLOCK_TIME_IS_VALID (requested)))
goto invalid_time;
/* a previously unscheduled entry cannot be scheduled again */
if (G_UNLIKELY (entry->status == GST_CLOCK_UNSCHEDULED))
goto unscheduled;
cclass = GST_CLOCK_GET_CLASS (clock);
if (cclass->wait_async) {
entry->func = func;
entry->user_data = user_data;
if (G_UNLIKELY (cclass->wait_async == NULL))
goto not_supported;
entry->func = func;
entry->user_data = user_data;
res = cclass->wait_async (clock, entry);
res = cclass->wait_async (clock, entry);
} else {
res = GST_CLOCK_UNSUPPORTED;
}
return res;
/* ERRORS */
......@@ -457,16 +487,21 @@ unscheduled:
"entry was unscheduled return _UNSCHEDULED");
return GST_CLOCK_UNSCHEDULED;
}
not_supported:
{
GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, clock, "clock wait is not supported");
return GST_CLOCK_UNSUPPORTED;
}
}
/**
* gst_clock_id_unschedule:
* @id: The id to unschedule
*
* Cancel an outstanding request with the given ID. This can either
* Cancel an outstanding request with @id. This can either
* be an outstanding async notification or a pending sync notification.
* After this call, the @id cannot be used anymore to receive sync or
* async notifications, you need to create a new GstClockID.
* After this call, @id cannot be used anymore to receive sync or
* async notifications, you need to create a new #GstClockID.
*
* MT safe.
*/
......@@ -484,7 +519,7 @@ gst_clock_id_unschedule (GstClockID id)
cclass = GST_CLOCK_GET_CLASS (clock);
if (cclass->unschedule)
if (G_LIKELY (cclass->unschedule))
cclass->unschedule (clock, entry);
}
......@@ -573,9 +608,9 @@ gst_clock_init (GstClock * clock)
clock->rate_denominator = 1;
clock->slave_lock = g_mutex_new ();
clock->filling = TRUE;
clock->window_size = DEFAULT_WINDOW_SIZE;
clock->window_threshold = DEFAULT_WINDOW_THRESHOLD;
clock->filling = TRUE;
clock->time_index = 0;
clock->timeout = DEFAULT_TIMEOUT;
clock->times = g_new0 (GstClockTime, 4 * clock->window_size);
......@@ -716,15 +751,23 @@ gst_clock_get_internal_time (GstClock * clock)
cclass = GST_CLOCK_GET_CLASS (clock);
if (cclass->get_internal_time) {
ret = cclass->get_internal_time (clock);
} else {
ret = G_GINT64_CONSTANT (0);
}
if (G_UNLIKELY (cclass->get_internal_time == NULL))
goto not_supported;
ret = cclass->get_internal_time (clock);
GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, clock, "internal time %" GST_TIME_FORMAT,
GST_TIME_ARGS (ret));
return ret;
/* ERRORS */
not_supported:
{
GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, clock,
"internal time not supported, return 0");
return G_GINT64_CONSTANT (0);
}
}
/**
......@@ -845,7 +888,7 @@ gst_clock_get_calibration (GstClock * clock, GstClockTime * internal,
}
/* will be called repeadedly to sample the master and slave clock
* to recalibrate the clock */
* to recalibrate the clock */
static gboolean
gst_clock_slave_callback (GstClock * master, GstClockTime time,
GstClockID id, GstClock * clock)
......@@ -880,7 +923,13 @@ gst_clock_slave_callback (GstClock * master, GstClockTime time,
* A clock provider that slaves its clock to a master can get the current
* calibration values with gst_clock_get_calibration().
*
* Returns: TRUE if the clock is capable of being slaved to a master clock.
* @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.
*
* 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.
*/
......@@ -919,6 +968,7 @@ gst_clock_set_master (GstClock * clock, GstClock * master)
return TRUE;
/* ERRORS */
not_supported:
{
GST_DEBUG_OBJECT (clock, "cannot be slaved to a master clock");
......@@ -1043,7 +1093,7 @@ do_linear_regression (GstClock * clock, GstClockTime * m_num,
sxy += newx4 * newy4 - xbar4 * ybar4;
}
if (sxx == 0)
if (G_UNLIKELY (sxx == 0))
goto invalid;
*m_num = sxy;
......@@ -1099,12 +1149,13 @@ gst_clock_add_observation (GstClock * clock, GstClockTime slave,
clock->times[(4 * clock->time_index) + 2] = master;
clock->time_index++;
if (clock->time_index == clock->window_size) {
if (G_UNLIKELY (clock->time_index == clock->window_size)) {
clock->filling = FALSE;
clock->time_index = 0;
}
if (clock->filling && clock->time_index < clock->window_threshold)
if (G_UNLIKELY (clock->filling
&& clock->time_index < clock->window_threshold))
goto filling;
if (!do_linear_regression (clock, &m_num, &m_denom, &b, &xbase, r_squared))
......@@ -1161,6 +1212,9 @@ gst_clock_set_property (GObject * object, guint prop_id,
MIN (clock->window_threshold, clock->window_size);
clock->times =
g_renew (GstClockTime, clock->times, 4 * clock->window_size);
/* restart calibration */
clock->filling = TRUE;
clock->time_index = 0;
GST_CLOCK_SLAVE_UNLOCK (clock);
break;
case PROP_WINDOW_THRESHOLD:
......
......@@ -112,6 +112,7 @@ typedef gpointer GstClockID;
* @e: the second time
*
* Calculate a difference between two clock times as a #GstClockTimeDiff.
* The difference is calculated as @e - @s.
*/
#define GST_CLOCK_DIFF(s, e) (GstClockTimeDiff)((e) - (s))
......
......@@ -35,7 +35,7 @@
* async notifications to implement their own callback methods or blocking
* wait operations.
*
* Last reviewed on 2005-10-28 (0.9.4)
* Last reviewed on 2006-03-08 (0.10.4)
*/
#include "gst_private.h"
......@@ -137,6 +137,7 @@ gst_system_clock_init (GstSystemClock * clock)
GST_OBJECT_UNLOCK (clock);
return;
/* ERRORS */
no_thread:
{
g_warning ("could not create async clock thread: %s", error->message);
......
......@@ -945,7 +945,6 @@ again:
/* send upstream */
gst_pad_push_event (basesink->sinkpad, event);
}
} else {
}
return GST_FLOW_OK;
......
......@@ -189,6 +189,20 @@ GST_START_TEST (test_periodic_shot)
gst_clock_id_unref (id);
}
GST_END_TEST
GST_START_TEST (test_diff)
{
GstClockTime time1[] =
{ 0, -1, 0, 1, 2 * GST_SECOND, -GST_SECOND, -GST_SECOND };
GstClockTime time2[] =
{ 0, 1, 1, 0, 1 * GST_SECOND, -GST_SECOND, GST_SECOND };
GstClockTimeDiff d[] = { 0, 2, 1, -1, -GST_SECOND, 0, 2 * GST_SECOND };
guint i;
for (i = 0; i < G_N_ELEMENTS (d); i++) {
fail_if (d[i] != GST_CLOCK_DIFF (time1[i], time2[i]));
}
}
GST_END_TEST Suite * gst_systemclock_suite (void)
{
Suite *s = suite_create ("GstSystemClock");
......@@ -198,6 +212,7 @@ GST_END_TEST Suite * gst_systemclock_suite (void)
tcase_add_test (tc_chain, test_signedness);
tcase_add_test (tc_chain, test_single_shot);
tcase_add_test (tc_chain, test_periodic_shot);
tcase_add_test (tc_chain, test_diff);
return s;
}
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment