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clocksync: Add a new property "sync-to-first" for automatic ts-offset setup

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Add a new property so that clocksync can setup "ts-offset" value
based on the first buffer and pipeline's running time when the
first arrived. Newly update "ts-offset" in this case would be
a value that allows outputting the first buffer without clock waiting.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/702>
This commit is contained in:
Seungha Yang 2020-11-18 22:32:30 +09:00 committed by GStreamer Marge Bot
parent c6a98609e5
commit 69e6cd773a
4 changed files with 175 additions and 8 deletions
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12
docs/plugins/gst_plugins_cache.json
View file

@ -92,6 +92,18 @@
"type": "gboolean",
"writable": true
},
"sync-to-first": {
"blurb": "Automatically set ts-offset based on running time of the first buffer and pipeline's running time (i.e., ts-offset = \"pipeline running time\" - \"buffer running time\"). When enabled, clocksync element will update ts-offset on the first buffer per flush event or READY to PAUSED state change. This property can be useful in case that buffer timestamp does not necessarily have to be synchronized with pipeline's running time, but duration of the buffer through clocksync element needs to be synchronized with the amount of clock time go. Note that mixed use of ts-offset and this property would be racy if clocksync element is running already.",
"conditionally-available": false,
"construct": false,
"construct-only": false,
"controllable": false,
"default": "false",
"mutable": "null",
"readable": true,
"type": "gboolean",
"writable": true
},
"ts-offset": {
"blurb": "Timestamp offset in nanoseconds for synchronisation, negative for earlier sync",
"conditionally-available": false,

98
plugins/elements/gstclocksync.c
View file

@ -56,14 +56,19 @@ GST_DEBUG_CATEGORY_STATIC (gst_clock_sync_debug);
/* ClockSync args */
#define DEFAULT_SYNC TRUE
#define DEFAULT_TS_OFFSET 0
#define DEFAULT_SYNC_TO_FIRST FALSE
enum
{
PROP_0,
PROP_SYNC,
PROP_TS_OFFSET
PROP_TS_OFFSET,
PROP_SYNC_TO_FIRST,
PROP_LAST
};
static GParamSpec *properties[PROP_LAST];
static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
@ -116,15 +121,42 @@ gst_clock_sync_class_init (GstClockSyncClass * klass)
gobject_class->get_property = gst_clock_sync_get_property;
gobject_class->finalize = gst_clock_sync_finalize;
g_object_class_install_property (gobject_class, PROP_SYNC,
properties[PROP_SYNC] =
g_param_spec_boolean ("sync", "Synchronize",
"Synchronize to pipeline clock", DEFAULT_SYNC,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (gobject_class, PROP_TS_OFFSET,
"Synchronize to pipeline clock", DEFAULT_SYNC,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
properties[PROP_TS_OFFSET] =
g_param_spec_int64 ("ts-offset", "Timestamp offset for synchronisation",
"Timestamp offset in nanoseconds for synchronisation, negative for earlier sync",
G_MININT64, G_MAXINT64, DEFAULT_TS_OFFSET,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
"Timestamp offset in nanoseconds for synchronisation, negative for earlier sync",
G_MININT64, G_MAXINT64, DEFAULT_TS_OFFSET,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
/**
* GstClockSync:sync-to-first:
*
* When enabled, clocksync elemenet will adjust "ts-offset" value
* automatically by using given timestamp of the first buffer and running
* time of pipeline, so that clocksync element can output the first buffer
* immediately without clock waiting.
*
* Since: 1.20
*/
properties[PROP_SYNC_TO_FIRST] =
g_param_spec_boolean ("sync-to-first",
"Sync to first",
"Automatically set ts-offset based on running time of the first "
"buffer and pipeline's running time "
"(i.e., ts-offset = \"pipeline running time\" - \"buffer running time\"). "
"When enabled, clocksync element will update ts-offset on the first "
"buffer per flush event or READY to PAUSED state change. "
"This property can be useful in case that buffer timestamp does not "
"necessarily have to be synchronized with pipeline's running time, "
"but duration of the buffer through clocksync element needs to be "
"synchronized with the amount of clock time go. "
"Note that mixed use of ts-offset and this property would be racy "
"if clocksync element is running already.",
DEFAULT_SYNC_TO_FIRST, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
g_object_class_install_properties (gobject_class, PROP_LAST, properties);
gstelement_class->change_state =
GST_DEBUG_FUNCPTR (gst_clocksync_change_state);
@ -172,6 +204,7 @@ gst_clock_sync_init (GstClockSync * clocksync)
clocksync->ts_offset = DEFAULT_TS_OFFSET;
clocksync->sync = DEFAULT_SYNC;
clocksync->sync_to_first = DEFAULT_SYNC_TO_FIRST;
g_cond_init (&clocksync->blocked_cond);
GST_OBJECT_FLAG_SET (clocksync, GST_ELEMENT_FLAG_REQUIRE_CLOCK);
@ -211,6 +244,9 @@ gst_clock_sync_set_property (GObject * object, guint prop_id,
case PROP_TS_OFFSET:
clocksync->ts_offset = g_value_get_int64 (value);
break;
case PROP_SYNC_TO_FIRST:
clocksync->sync_to_first = g_value_get_boolean (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
@ -230,6 +266,9 @@ gst_clock_sync_get_property (GObject * object, guint prop_id,
case PROP_TS_OFFSET:
g_value_set_int64 (value, clocksync->ts_offset);
break;
case PROP_SYNC_TO_FIRST:
g_value_set_boolean (value, clocksync->sync_to_first);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
@ -346,6 +385,8 @@ gst_clock_sync_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
clocksync->flushing = FALSE;
gst_segment_init (&clocksync->segment, GST_FORMAT_UNDEFINED);
GST_OBJECT_UNLOCK (clocksync);
clocksync->is_first = TRUE;
break;
default:
break;
}
@ -355,6 +396,42 @@ gst_clock_sync_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
return ret;
}
static void
gst_clock_sync_update_ts_offset (GstClockSync * clocksync,
GstClockTime runtimestamp)
{
GstClock *clock;
GstClockTimeDiff ts_offset = 0;
GstClockTime running_time;
if (!clocksync->sync_to_first || !clocksync->is_first || !clocksync->sync)
return;
GST_OBJECT_LOCK (clocksync);
clock = GST_ELEMENT_CLOCK (clocksync);
if (!clock) {
GST_DEBUG_OBJECT (clocksync, "We have no clock");
GST_OBJECT_UNLOCK (clocksync);
return;
}
running_time = gst_clock_get_time (clock) -
GST_ELEMENT_CAST (clocksync)->base_time;
ts_offset = GST_CLOCK_DIFF (runtimestamp, running_time);
GST_OBJECT_UNLOCK (clocksync);
GST_DEBUG_OBJECT (clocksync, "Running time %" GST_TIME_FORMAT
", running time stamp %" GST_TIME_FORMAT ", calculated ts-offset %"
GST_STIME_FORMAT, GST_TIME_ARGS (running_time),
GST_TIME_ARGS (runtimestamp), GST_STIME_ARGS (ts_offset));
clocksync->is_first = FALSE;
if (ts_offset != clocksync->ts_offset) {
clocksync->ts_offset = ts_offset;
g_object_notify_by_pspec (G_OBJECT (clocksync), properties[PROP_TS_OFFSET]);
}
}
static GstFlowReturn
gst_clock_sync_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
{
@ -388,6 +465,8 @@ gst_clock_sync_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
else if (GST_CLOCK_TIME_IS_VALID (runpts))
runtimestamp = runpts;
gst_clock_sync_update_ts_offset (clocksync, runtimestamp);
ret = gst_clocksync_do_sync (clocksync, runtimestamp);
if (ret != GST_FLOW_OK) {
GST_LOG_OBJECT (clocksync,
@ -431,6 +510,8 @@ gst_clock_sync_chain_list (GstPad * pad, GstObject * parent,
else if (GST_CLOCK_TIME_IS_VALID (runpts))
runtimestamp = runpts;
gst_clock_sync_update_ts_offset (clocksync, runtimestamp);
ret = gst_clocksync_do_sync (clocksync, runtimestamp);
if (ret != GST_FLOW_OK) {
gst_buffer_list_unref (buffer_list);
@ -512,6 +593,7 @@ gst_clocksync_change_state (GstElement * element, GstStateChange transition)
GST_OBJECT_UNLOCK (clocksync);
if (clocksync->sync)
no_preroll = TRUE;
clocksync->is_first = TRUE;
break;
case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
GST_OBJECT_LOCK (clocksync);

2
plugins/elements/gstclocksync.h
View file

@ -59,6 +59,8 @@ struct _GstClockSync
GCond blocked_cond;
gboolean blocked;
GstClockTimeDiff ts_offset;
gboolean sync_to_first;
gboolean is_first;
GstClockTime upstream_latency;
};

71
tests/check/elements/clocksync.c
View file

@ -168,6 +168,76 @@ GST_START_TEST (test_stopping_element_unschedules_sync)
GST_END_TEST;
typedef struct
{
guint notify_count;
GstClockTimeDiff ts_offset;
} ClockSyncTestData;
static void
clock_sync_ts_offset_changed_cb (GstElement * clocksync, GParamSpec * pspec,
ClockSyncTestData * data)
{
data->notify_count++;
g_object_get (clocksync, "ts-offset", &data->ts_offset, NULL);
}
GST_START_TEST (test_sync_to_first)
{
/* the reason to use the queue in front of the clocksync element
is to effectively make gst_harness_push asynchronous, not locking
up the test, waiting for gst_clock_id_wait */
GstHarness *h =
gst_harness_new_parse ("queue ! clocksync sync-to-first=true");
GstBuffer *buf;
GstClock *clock;
GstClockTime timestamp = 123456789;
GstElement *clocksync;
ClockSyncTestData data;
data.notify_count = 0;
data.ts_offset = 0;
clocksync = gst_harness_find_element (h, "clocksync");
g_signal_connect (clocksync, "notify::ts-offset",
G_CALLBACK (clock_sync_ts_offset_changed_cb), &data);
gst_object_unref (clocksync);
/* use testclock */
gst_harness_use_testclock (h);
gst_harness_set_src_caps_str (h, "mycaps");
/* make a buffer and set the timestamp */
buf = gst_buffer_new ();
GST_BUFFER_PTS (buf) = timestamp;
/* push the buffer, and verify it does *not* make it through */
gst_harness_push (h, buf);
fail_unless_equals_int (0, gst_harness_buffers_in_queue (h));
/* verify the clocksync element has registered exactly one GstClockID */
fail_unless (gst_harness_wait_for_clock_id_waits (h, 1, 42));
/* crank the clock and pull the buffer */
gst_harness_crank_single_clock_wait (h);
buf = gst_harness_pull (h);
/* verify that the buffer has the right timestamp, and that the time on
the clock is equal to the timestamp */
fail_unless_equals_int64 (timestamp, GST_BUFFER_PTS (buf));
clock = gst_element_get_clock (h->element);
/* this buffer must be pushed without clock waiting */
fail_unless_equals_int64 (gst_clock_get_time (clock), 0);
fail_unless_equals_int (data.notify_count, 1);
fail_unless_equals_int64 (data.ts_offset, -timestamp);
/* cleanup */
gst_object_unref (clock);
gst_buffer_unref (buf);
gst_harness_teardown (h);
}
GST_END_TEST;
static Suite *
clocksync_suite (void)
{
@ -179,6 +249,7 @@ clocksync_suite (void)
tcase_add_test (tc_chain, test_sync_on_timestamp);
tcase_add_test (tc_chain, test_stopping_element_unschedules_sync);
tcase_add_test (tc_chain, test_no_sync_on_timestamp);
tcase_add_test (tc_chain, test_sync_to_first);
return s;