/* GStreamer * Copyright (C) 1999,2000 Erik Walthinsen * 2005 Wim Taymans * 2005 Andy Wingo * Copyright (C) 2012 Collabora Ltd. * Copyright (C) 2015 Sebastian Dröge * * gstnetclientclock.h: clock that synchronizes itself to a time provider over * the network * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library 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 * Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, * Boston, MA 02110-1301, USA. */ /** * SECTION:gstnetclientclock * @title: GstNetClientClock * @short_description: Special clock that synchronizes to a remote time * provider. * @see_also: #GstClock, #GstNetTimeProvider, #GstPipeline * * #GstNetClientClock implements a custom #GstClock that synchronizes its time * to a remote time provider such as #GstNetTimeProvider. #GstNtpClock * implements a #GstClock that synchronizes its time to a remote NTPv4 server. * * A new clock is created with gst_net_client_clock_new() or * gst_ntp_clock_new(), which takes the address and port of the remote time * provider along with a name and an initial time. * * This clock will poll the time provider and will update its calibration * parameters based on the local and remote observations. * * The "round-trip" property limits the maximum round trip packets can take. * * Various parameters of the clock can be configured with the parent #GstClock * "timeout", "window-size" and "window-threshold" object properties. * * A #GstNetClientClock and #GstNtpClock is typically set on a #GstPipeline with * gst_pipeline_use_clock(). * * If you set a #GstBus on the clock via the "bus" object property, it will * send @GST_MESSAGE_ELEMENT messages with an attached #GstStructure containing * statistics about clock accuracy and network traffic. */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include "gstnettimepacket.h" #include "gstntppacket.h" #include "gstnetclientclock.h" #include "gstnetutils.h" #include #include GST_DEBUG_CATEGORY_STATIC (ncc_debug); #define GST_CAT_DEFAULT (ncc_debug) typedef struct { GstClock *clock; /* GstNetClientInternalClock */ GList *clocks; /* GstNetClientClocks */ GstClockID remove_id; } ClockCache; G_LOCK_DEFINE_STATIC (clocks_lock); static GList *clocks = NULL; #define GST_TYPE_NET_CLIENT_INTERNAL_CLOCK \ (gst_net_client_internal_clock_get_type()) #define GST_NET_CLIENT_INTERNAL_CLOCK(obj) \ (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_NET_CLIENT_INTERNAL_CLOCK,GstNetClientInternalClock)) #define GST_NET_CLIENT_INTERNAL_CLOCK_CLASS(klass) \ (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_NET_CLIENT_INTERNAL_CLOCK,GstNetClientInternalClockClass)) #define GST_IS_NET_CLIENT_INTERNAL_CLOCK(obj) \ (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_NET_CLIENT_INTERNAL_CLOCK)) #define GST_IS_NET_CLIENT_INTERNAL_CLOCK_CLASS(klass) \ (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_NET_CLIENT_INTERNAL_CLOCK)) typedef struct _GstNetClientInternalClock GstNetClientInternalClock; typedef struct _GstNetClientInternalClockClass GstNetClientInternalClockClass; G_GNUC_INTERNAL GType gst_net_client_internal_clock_get_type (void); #define DEFAULT_ADDRESS "127.0.0.1" #define DEFAULT_PORT 5637 #define DEFAULT_TIMEOUT GST_SECOND #define DEFAULT_ROUNDTRIP_LIMIT GST_SECOND /* Minimum timeout will be immediately (ie, as fast as one RTT), but no * more often than 1/20th second (arbitrarily, to spread observations a little) */ #define DEFAULT_MINIMUM_UPDATE_INTERVAL (GST_SECOND / 20) #define DEFAULT_BASE_TIME 0 #define DEFAULT_QOS_DSCP -1 /* Maximum number of clock updates we can skip before updating */ #define MAX_SKIPPED_UPDATES 5 #define MEDIAN_PRE_FILTERING_WINDOW 9 enum { PROP_0, PROP_ADDRESS, PROP_PORT, PROP_ROUNDTRIP_LIMIT, PROP_MINIMUM_UPDATE_INTERVAL, PROP_BUS, PROP_BASE_TIME, PROP_INTERNAL_CLOCK, PROP_IS_NTP, PROP_QOS_DSCP }; struct _GstNetClientInternalClock { GstSystemClock clock; GThread *thread; GSocket *socket; GSocketAddress *servaddr; GCancellable *cancel; gboolean made_cancel_fd; GstClockTime timeout_expiration; GstClockTime roundtrip_limit; GstClockTime rtt_avg; GstClockTime minimum_update_interval; GstClockTime last_remote_poll_interval; guint skipped_updates; GstClockTime last_rtts[MEDIAN_PRE_FILTERING_WINDOW]; gint last_rtts_missing; gchar *address; gint port; gboolean is_ntp; gint qos_dscp; /* Protected by OBJECT_LOCK */ GList *busses; }; struct _GstNetClientInternalClockClass { GstSystemClockClass parent_class; }; #define _do_init \ GST_DEBUG_CATEGORY_INIT (ncc_debug, "netclock", 0, "Network client clock"); G_DEFINE_TYPE_WITH_CODE (GstNetClientInternalClock, gst_net_client_internal_clock, GST_TYPE_SYSTEM_CLOCK, _do_init); static void gst_net_client_internal_clock_finalize (GObject * object); static void gst_net_client_internal_clock_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec); static void gst_net_client_internal_clock_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec); static void gst_net_client_internal_clock_constructed (GObject * object); static gboolean gst_net_client_internal_clock_start (GstNetClientInternalClock * self); static void gst_net_client_internal_clock_stop (GstNetClientInternalClock * self); static void gst_net_client_internal_clock_class_init (GstNetClientInternalClockClass * klass) { GObjectClass *gobject_class; gobject_class = G_OBJECT_CLASS (klass); gobject_class->finalize = gst_net_client_internal_clock_finalize; gobject_class->get_property = gst_net_client_internal_clock_get_property; gobject_class->set_property = gst_net_client_internal_clock_set_property; gobject_class->constructed = gst_net_client_internal_clock_constructed; g_object_class_install_property (gobject_class, PROP_ADDRESS, g_param_spec_string ("address", "address", "The IP address of the machine providing a time server", DEFAULT_ADDRESS, G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS)); g_object_class_install_property (gobject_class, PROP_PORT, g_param_spec_int ("port", "port", "The port on which the remote server is listening", 0, G_MAXUINT16, DEFAULT_PORT, G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS)); g_object_class_install_property (gobject_class, PROP_IS_NTP, g_param_spec_boolean ("is-ntp", "Is NTP", "The clock is using the NTPv4 protocol", FALSE, G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS)); } static void gst_net_client_internal_clock_init (GstNetClientInternalClock * self) { GST_OBJECT_FLAG_SET (self, GST_CLOCK_FLAG_NEEDS_STARTUP_SYNC); self->port = DEFAULT_PORT; self->address = g_strdup (DEFAULT_ADDRESS); self->is_ntp = FALSE; self->qos_dscp = DEFAULT_QOS_DSCP; gst_clock_set_timeout (GST_CLOCK (self), DEFAULT_TIMEOUT); self->thread = NULL; self->servaddr = NULL; self->rtt_avg = GST_CLOCK_TIME_NONE; self->roundtrip_limit = DEFAULT_ROUNDTRIP_LIMIT; self->minimum_update_interval = DEFAULT_MINIMUM_UPDATE_INTERVAL; self->last_remote_poll_interval = GST_CLOCK_TIME_NONE; self->skipped_updates = 0; self->last_rtts_missing = MEDIAN_PRE_FILTERING_WINDOW; } static void gst_net_client_internal_clock_finalize (GObject * object) { GstNetClientInternalClock *self = GST_NET_CLIENT_INTERNAL_CLOCK (object); if (self->thread) { gst_net_client_internal_clock_stop (self); } g_free (self->address); self->address = NULL; if (self->servaddr != NULL) { g_object_unref (self->servaddr); self->servaddr = NULL; } if (self->socket != NULL) { if (!g_socket_close (self->socket, NULL)) GST_ERROR_OBJECT (self, "Failed to close socket"); g_object_unref (self->socket); self->socket = NULL; } g_warn_if_fail (self->busses == NULL); G_OBJECT_CLASS (gst_net_client_internal_clock_parent_class)->finalize (object); } static void gst_net_client_internal_clock_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) { GstNetClientInternalClock *self = GST_NET_CLIENT_INTERNAL_CLOCK (object); switch (prop_id) { case PROP_ADDRESS: GST_OBJECT_LOCK (self); g_free (self->address); self->address = g_value_dup_string (value); if (self->address == NULL) self->address = g_strdup (DEFAULT_ADDRESS); GST_OBJECT_UNLOCK (self); break; case PROP_PORT: GST_OBJECT_LOCK (self); self->port = g_value_get_int (value); GST_OBJECT_UNLOCK (self); break; case PROP_IS_NTP: GST_OBJECT_LOCK (self); self->is_ntp = g_value_get_boolean (value); GST_OBJECT_UNLOCK (self); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } } static void gst_net_client_internal_clock_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec) { GstNetClientInternalClock *self = GST_NET_CLIENT_INTERNAL_CLOCK (object); switch (prop_id) { case PROP_ADDRESS: GST_OBJECT_LOCK (self); g_value_set_string (value, self->address); GST_OBJECT_UNLOCK (self); break; case PROP_PORT: g_value_set_int (value, self->port); break; case PROP_IS_NTP: g_value_set_boolean (value, self->is_ntp); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } } static void gst_net_client_internal_clock_constructed (GObject * object) { GstNetClientInternalClock *self = GST_NET_CLIENT_INTERNAL_CLOCK (object); G_OBJECT_CLASS (gst_net_client_internal_clock_parent_class)->constructed (object); if (!gst_net_client_internal_clock_start (self)) { g_warning ("failed to start clock '%s'", GST_OBJECT_NAME (self)); } /* all systems go, cap'n */ } static gint compare_clock_time (const GstClockTime * a, const GstClockTime * b) { if (*a < *b) return -1; else if (*a > *b) return 1; return 0; } static void gst_net_client_internal_clock_observe_times (GstNetClientInternalClock * self, GstClockTime local_1, GstClockTime remote_1, GstClockTime remote_2, GstClockTime local_2) { GstClockTime current_timeout = 0; GstClockTime local_avg, remote_avg; gdouble r_squared; GstClock *clock; GstClockTime rtt, rtt_limit, min_update_interval; /* Use for discont tracking */ GstClockTime time_before = 0; GstClockTime min_guess = 0; GstClockTimeDiff time_discont = 0; gboolean synched, now_synched; GstClockTime internal_time, external_time, rate_num, rate_den; GstClockTime orig_internal_time, orig_external_time, orig_rate_num, orig_rate_den; GstClockTime max_discont; GstClockTime last_rtts[MEDIAN_PRE_FILTERING_WINDOW]; GstClockTime median; gint i; GST_OBJECT_LOCK (self); rtt_limit = self->roundtrip_limit; GST_LOG_OBJECT (self, "local1 %" G_GUINT64_FORMAT " remote1 %" G_GUINT64_FORMAT " remote2 %" G_GUINT64_FORMAT " local2 %" G_GUINT64_FORMAT, local_1, remote_1, remote_2, local_2); /* If the server told us a poll interval and it's bigger than the * one configured via the property, use the server's */ if (self->last_remote_poll_interval != GST_CLOCK_TIME_NONE && self->last_remote_poll_interval > self->minimum_update_interval) min_update_interval = self->last_remote_poll_interval; else min_update_interval = self->minimum_update_interval; GST_OBJECT_UNLOCK (self); if (local_2 < local_1) { GST_LOG_OBJECT (self, "Dropping observation: receive time %" GST_TIME_FORMAT " < send time %" GST_TIME_FORMAT, GST_TIME_ARGS (local_1), GST_TIME_ARGS (local_2)); goto bogus_observation; } if (remote_2 < remote_1) { GST_LOG_OBJECT (self, "Dropping observation: remote receive time %" GST_TIME_FORMAT " < send time %" GST_TIME_FORMAT, GST_TIME_ARGS (remote_1), GST_TIME_ARGS (remote_2)); goto bogus_observation; } /* The round trip time is (assuming symmetric path delays) * delta = (local_2 - local_1) - (remote_2 - remote_1) */ rtt = GST_CLOCK_DIFF (local_1, local_2) - GST_CLOCK_DIFF (remote_1, remote_2); if ((rtt_limit > 0) && (rtt > rtt_limit)) { GST_LOG_OBJECT (self, "Dropping observation: RTT %" GST_TIME_FORMAT " > limit %" GST_TIME_FORMAT, GST_TIME_ARGS (rtt), GST_TIME_ARGS (rtt_limit)); goto bogus_observation; } for (i = 1; i < MEDIAN_PRE_FILTERING_WINDOW; i++) self->last_rtts[i - 1] = self->last_rtts[i]; self->last_rtts[i - 1] = rtt; if (self->last_rtts_missing) { self->last_rtts_missing--; } else { memcpy (&last_rtts, &self->last_rtts, sizeof (last_rtts)); g_qsort_with_data (&last_rtts, MEDIAN_PRE_FILTERING_WINDOW, sizeof (GstClockTime), (GCompareDataFunc) compare_clock_time, NULL); median = last_rtts[MEDIAN_PRE_FILTERING_WINDOW / 2]; /* FIXME: We might want to use something else here, like only allowing * things in the interquartile range, or also filtering away delays that * are too small compared to the median. This here worked well enough * in tests so far. */ if (rtt > 2 * median) { GST_LOG_OBJECT (self, "Dropping observation, long RTT %" GST_TIME_FORMAT " > 2 * median %" GST_TIME_FORMAT, GST_TIME_ARGS (rtt), GST_TIME_ARGS (median)); goto bogus_observation; } } /* Track an average round trip time, for a bit of smoothing */ /* Always update before discarding a sample, so genuine changes in * the network get picked up, eventually */ if (self->rtt_avg == GST_CLOCK_TIME_NONE) self->rtt_avg = rtt; else if (rtt < self->rtt_avg) /* Shorter RTTs carry more weight than longer */ self->rtt_avg = (3 * self->rtt_avg + rtt) / 4; else self->rtt_avg = (15 * self->rtt_avg + rtt) / 16; if (rtt > 2 * self->rtt_avg) { GST_LOG_OBJECT (self, "Dropping observation, long RTT %" GST_TIME_FORMAT " > 2 * avg %" GST_TIME_FORMAT, GST_TIME_ARGS (rtt), GST_TIME_ARGS (self->rtt_avg)); goto bogus_observation; } /* The difference between the local and remote clock (again assuming * symmetric path delays): * * local_1 + delta / 2 - remote_1 = theta * or * local_2 - delta / 2 - remote_2 = theta * * which gives after some simple algebraic transformations: * * (remote_1 - local_1) + (remote_2 - local_2) * theta = ------------------------------------------- * 2 * * * Thus remote time at local_avg is equal to: * * local_avg + theta = * * local_1 + local_2 (remote_1 - local_1) + (remote_2 - local_2) * ----------------- + ------------------------------------------- * 2 2 * * = * * remote_1 + remote_2 * ------------------- = remote_avg * 2 * * We use this for our clock estimation, i.e. local_avg at remote clock * being the same as remote_avg. */ local_avg = (local_2 + local_1) / 2; remote_avg = (remote_2 + remote_1) / 2; GST_LOG_OBJECT (self, "remoteavg %" G_GUINT64_FORMAT " localavg %" G_GUINT64_FORMAT, remote_avg, local_avg); clock = GST_CLOCK_CAST (self); /* Store what the clock produced as 'now' before this update */ gst_clock_get_calibration (GST_CLOCK_CAST (self), &orig_internal_time, &orig_external_time, &orig_rate_num, &orig_rate_den); internal_time = orig_internal_time; external_time = orig_external_time; rate_num = orig_rate_num; rate_den = orig_rate_den; min_guess = gst_clock_adjust_with_calibration (GST_CLOCK_CAST (self), local_1, internal_time, external_time, rate_num, rate_den); time_before = gst_clock_adjust_with_calibration (GST_CLOCK_CAST (self), local_2, internal_time, external_time, rate_num, rate_den); /* Maximum discontinuity, when we're synched with the master. Could make this a property, * but this value seems to work fine */ max_discont = self->rtt_avg / 4; /* If the remote observation was within a max_discont window around our min/max estimates, we're synched */ synched = (GST_CLOCK_DIFF (remote_avg, min_guess) < (GstClockTimeDiff) (max_discont) && GST_CLOCK_DIFF (time_before, remote_avg) < (GstClockTimeDiff) (max_discont)); if (gst_clock_add_observation_unapplied (GST_CLOCK_CAST (self), local_avg, remote_avg, &r_squared, &internal_time, &external_time, &rate_num, &rate_den)) { /* Now compare the difference (discont) in the clock * after this observation */ time_discont = GST_CLOCK_DIFF (time_before, gst_clock_adjust_with_calibration (GST_CLOCK_CAST (self), local_2, internal_time, external_time, rate_num, rate_den)); /* If we were in sync with the remote clock, clamp the allowed * discontinuity to within quarter of one RTT. In sync means our send/receive estimates * of remote time correctly windowed the actual remote time observation */ if (synched && ABS (time_discont) > max_discont) { GstClockTimeDiff offset; GST_DEBUG_OBJECT (clock, "Too large a discont, clamping to 1/4 average RTT = %" GST_TIME_FORMAT, GST_TIME_ARGS (max_discont)); if (time_discont > 0) { /* Too large a forward step - add a -ve offset */ offset = max_discont - time_discont; if (-offset > external_time) external_time = 0; else external_time += offset; } else { /* Too large a backward step - add a +ve offset */ offset = -(max_discont + time_discont); external_time += offset; } time_discont += offset; } /* Check if the new clock params would have made our observation within range */ now_synched = (GST_CLOCK_DIFF (remote_avg, gst_clock_adjust_with_calibration (GST_CLOCK_CAST (self), local_1, internal_time, external_time, rate_num, rate_den)) < (GstClockTimeDiff) (max_discont)) && (GST_CLOCK_DIFF (gst_clock_adjust_with_calibration (GST_CLOCK_CAST (self), local_2, internal_time, external_time, rate_num, rate_den), remote_avg) < (GstClockTimeDiff) (max_discont)); /* Only update the clock if we had synch or just gained it */ if (synched || now_synched || self->skipped_updates > MAX_SKIPPED_UPDATES) { gst_clock_set_calibration (GST_CLOCK_CAST (self), internal_time, external_time, rate_num, rate_den); /* ghetto formula - shorter timeout for bad correlations */ current_timeout = (1e-3 / (1 - MIN (r_squared, 0.99999))) * GST_SECOND; current_timeout = MIN (current_timeout, gst_clock_get_timeout (GST_CLOCK_CAST (self))); self->skipped_updates = 0; /* FIXME: When do we consider the clock absolutely not synced anymore? */ gst_clock_set_synced (GST_CLOCK (self), TRUE); } else { /* Restore original calibration vars for the report, we're not changing the clock */ internal_time = orig_internal_time; external_time = orig_external_time; rate_num = orig_rate_num; rate_den = orig_rate_den; time_discont = 0; self->skipped_updates++; } } /* Limit the polling to at most one per minimum_update_interval */ if (rtt < min_update_interval) current_timeout = MAX (min_update_interval - rtt, current_timeout); GST_OBJECT_LOCK (self); if (self->busses) { GstStructure *s; GstMessage *msg; GList *l; /* Output a stats message, whether we updated the clock or not */ s = gst_structure_new ("gst-netclock-statistics", "synchronised", G_TYPE_BOOLEAN, synched, "rtt", G_TYPE_UINT64, rtt, "rtt-average", G_TYPE_UINT64, self->rtt_avg, "local", G_TYPE_UINT64, local_avg, "remote", G_TYPE_UINT64, remote_avg, "discontinuity", G_TYPE_INT64, time_discont, "remote-min-estimate", G_TYPE_UINT64, min_guess, "remote-max-estimate", G_TYPE_UINT64, time_before, "remote-min-error", G_TYPE_INT64, GST_CLOCK_DIFF (remote_avg, min_guess), "remote-max-error", G_TYPE_INT64, GST_CLOCK_DIFF (remote_avg, time_before), "request-send", G_TYPE_UINT64, local_1, "request-receive", G_TYPE_UINT64, local_2, "r-squared", G_TYPE_DOUBLE, r_squared, "timeout", G_TYPE_UINT64, current_timeout, "internal-time", G_TYPE_UINT64, internal_time, "external-time", G_TYPE_UINT64, external_time, "rate-num", G_TYPE_UINT64, rate_num, "rate-den", G_TYPE_UINT64, rate_den, "rate", G_TYPE_DOUBLE, (gdouble) (rate_num) / rate_den, "local-clock-offset", G_TYPE_INT64, GST_CLOCK_DIFF (internal_time, external_time), NULL); msg = gst_message_new_element (GST_OBJECT (self), s); for (l = self->busses; l; l = l->next) gst_bus_post (l->data, gst_message_ref (msg)); gst_message_unref (msg); } GST_OBJECT_UNLOCK (self); GST_INFO ("next timeout: %" GST_TIME_FORMAT, GST_TIME_ARGS (current_timeout)); self->timeout_expiration = gst_util_get_timestamp () + current_timeout; return; bogus_observation: /* Schedule a new packet again soon */ self->timeout_expiration = gst_util_get_timestamp () + (GST_SECOND / 4); return; } static gpointer gst_net_client_internal_clock_thread (gpointer data) { GstNetClientInternalClock *self = data; GSocket *socket = self->socket; GError *err = NULL; gint cur_qos_dscp = DEFAULT_QOS_DSCP; GST_INFO_OBJECT (self, "net client clock thread running, socket=%p", socket); g_socket_set_blocking (socket, TRUE); g_socket_set_timeout (socket, 0); while (!g_cancellable_is_cancelled (self->cancel)) { GstClockTime expiration_time = self->timeout_expiration; GstClockTime now = gst_util_get_timestamp (); gint64 socket_timeout; if (now >= expiration_time || (expiration_time - now) <= GST_MSECOND) { socket_timeout = 0; } else { socket_timeout = (expiration_time - now) / GST_USECOND; } GST_TRACE_OBJECT (self, "timeout: %" G_GINT64_FORMAT "us", socket_timeout); if (!g_socket_condition_timed_wait (socket, G_IO_IN, socket_timeout, self->cancel, &err)) { /* cancelled, timeout or error */ if (err->code == G_IO_ERROR_CANCELLED) { GST_INFO_OBJECT (self, "cancelled"); g_clear_error (&err); break; } else if (err->code == G_IO_ERROR_TIMED_OUT) { gint new_qos_dscp; /* timed out, let's send another packet */ GST_DEBUG_OBJECT (self, "timed out"); /* before next sending check if need to change QoS */ new_qos_dscp = self->qos_dscp; if (cur_qos_dscp != new_qos_dscp && gst_net_utils_set_socket_dscp (socket, new_qos_dscp)) { GST_DEBUG_OBJECT (self, "changed QoS DSCP to: %d", new_qos_dscp); cur_qos_dscp = new_qos_dscp; } if (self->is_ntp) { GstNtpPacket *packet; packet = gst_ntp_packet_new (NULL, NULL); packet->transmit_time = gst_clock_get_internal_time (GST_CLOCK_CAST (self)); GST_DEBUG_OBJECT (self, "sending packet, local time = %" GST_TIME_FORMAT, GST_TIME_ARGS (packet->transmit_time)); gst_ntp_packet_send (packet, self->socket, self->servaddr, NULL); g_free (packet); } else { GstNetTimePacket *packet; packet = gst_net_time_packet_new (NULL); packet->local_time = gst_clock_get_internal_time (GST_CLOCK_CAST (self)); GST_DEBUG_OBJECT (self, "sending packet, local time = %" GST_TIME_FORMAT, GST_TIME_ARGS (packet->local_time)); gst_net_time_packet_send (packet, self->socket, self->servaddr, NULL); g_free (packet); } /* reset timeout (but are expecting a response sooner anyway) */ self->timeout_expiration = gst_util_get_timestamp () + gst_clock_get_timeout (GST_CLOCK_CAST (self)); } else { GST_DEBUG_OBJECT (self, "socket error: %s", err->message); g_usleep (G_USEC_PER_SEC / 10); /* throttle */ } g_clear_error (&err); } else { GstClockTime new_local; /* got packet */ new_local = gst_clock_get_internal_time (GST_CLOCK_CAST (self)); if (self->is_ntp) { GstNtpPacket *packet; packet = gst_ntp_packet_receive (socket, NULL, &err); if (packet != NULL) { GST_LOG_OBJECT (self, "got packet back"); GST_LOG_OBJECT (self, "local_1 = %" GST_TIME_FORMAT, GST_TIME_ARGS (packet->origin_time)); GST_LOG_OBJECT (self, "remote_1 = %" GST_TIME_FORMAT, GST_TIME_ARGS (packet->receive_time)); GST_LOG_OBJECT (self, "remote_2 = %" GST_TIME_FORMAT, GST_TIME_ARGS (packet->transmit_time)); GST_LOG_OBJECT (self, "local_2 = %" GST_TIME_FORMAT, GST_TIME_ARGS (new_local)); GST_LOG_OBJECT (self, "poll_interval = %" GST_TIME_FORMAT, GST_TIME_ARGS (packet->poll_interval)); /* Remember the last poll interval we ever got from the server */ if (packet->poll_interval != GST_CLOCK_TIME_NONE) self->last_remote_poll_interval = packet->poll_interval; /* observe_times will reset the timeout */ gst_net_client_internal_clock_observe_times (self, packet->origin_time, packet->receive_time, packet->transmit_time, new_local); g_free (packet); } else if (err != NULL) { if (g_error_matches (err, GST_NTP_ERROR, GST_NTP_ERROR_WRONG_VERSION) || g_error_matches (err, GST_NTP_ERROR, GST_NTP_ERROR_KOD_DENY)) { GST_ERROR_OBJECT (self, "fatal receive error: %s", err->message); g_clear_error (&err); break; } else if (g_error_matches (err, GST_NTP_ERROR, GST_NTP_ERROR_KOD_RATE)) { GST_WARNING_OBJECT (self, "need to limit rate"); /* If the server did not tell us a poll interval before, double * our minimum poll interval. Otherwise we assume that the server * already told us something sensible and that this error here * was just a spurious error */ if (self->last_remote_poll_interval == GST_CLOCK_TIME_NONE) self->minimum_update_interval *= 2; /* And wait a bit before we send the next packet instead of * sending it immediately */ self->timeout_expiration = gst_util_get_timestamp () + gst_clock_get_timeout (GST_CLOCK_CAST (self)); } else { GST_WARNING_OBJECT (self, "receive error: %s", err->message); } g_clear_error (&err); } } else { GstNetTimePacket *packet; packet = gst_net_time_packet_receive (socket, NULL, &err); if (packet != NULL) { GST_LOG_OBJECT (self, "got packet back"); GST_LOG_OBJECT (self, "local_1 = %" GST_TIME_FORMAT, GST_TIME_ARGS (packet->local_time)); GST_LOG_OBJECT (self, "remote = %" GST_TIME_FORMAT, GST_TIME_ARGS (packet->remote_time)); GST_LOG_OBJECT (self, "local_2 = %" GST_TIME_FORMAT, GST_TIME_ARGS (new_local)); /* observe_times will reset the timeout */ gst_net_client_internal_clock_observe_times (self, packet->local_time, packet->remote_time, packet->remote_time, new_local); g_free (packet); } else if (err != NULL) { GST_WARNING_OBJECT (self, "receive error: %s", err->message); g_clear_error (&err); } } } } GST_INFO_OBJECT (self, "shutting down net client clock thread"); return NULL; } static gboolean gst_net_client_internal_clock_start (GstNetClientInternalClock * self) { GSocketAddress *servaddr; GSocketAddress *myaddr; GSocketAddress *anyaddr; GInetAddress *inetaddr; GSocket *socket; GError *error = NULL; GSocketFamily family; GPollFD dummy_pollfd; GResolver *resolver = NULL; GError *err = NULL; g_return_val_if_fail (self->address != NULL, FALSE); g_return_val_if_fail (self->servaddr == NULL, FALSE); /* create target address */ inetaddr = g_inet_address_new_from_string (self->address); if (inetaddr == NULL) { GList *results; resolver = g_resolver_get_default (); results = g_resolver_lookup_by_name (resolver, self->address, NULL, &err); if (!results) goto failed_to_resolve; inetaddr = G_INET_ADDRESS (g_object_ref (results->data)); g_resolver_free_addresses (results); g_object_unref (resolver); } family = g_inet_address_get_family (inetaddr); servaddr = g_inet_socket_address_new (inetaddr, self->port); g_object_unref (inetaddr); g_assert (servaddr != NULL); GST_DEBUG_OBJECT (self, "will communicate with %s:%d", self->address, self->port); socket = g_socket_new (family, G_SOCKET_TYPE_DATAGRAM, G_SOCKET_PROTOCOL_UDP, &error); if (socket == NULL) goto no_socket; GST_DEBUG_OBJECT (self, "binding socket"); inetaddr = g_inet_address_new_any (family); anyaddr = g_inet_socket_address_new (inetaddr, 0); g_socket_bind (socket, anyaddr, TRUE, &error); g_object_unref (anyaddr); g_object_unref (inetaddr); if (error != NULL) goto bind_error; /* check address we're bound to, mostly for debugging purposes */ myaddr = g_socket_get_local_address (socket, &error); if (myaddr == NULL) goto getsockname_error; GST_DEBUG_OBJECT (self, "socket opened on UDP port %d", g_inet_socket_address_get_port (G_INET_SOCKET_ADDRESS (myaddr))); g_object_unref (myaddr); self->cancel = g_cancellable_new (); self->made_cancel_fd = g_cancellable_make_pollfd (self->cancel, &dummy_pollfd); self->socket = socket; self->servaddr = G_SOCKET_ADDRESS (servaddr); self->thread = g_thread_try_new ("GstNetClientInternalClock", gst_net_client_internal_clock_thread, self, &error); if (error != NULL) goto no_thread; return TRUE; /* ERRORS */ no_socket: { GST_ERROR_OBJECT (self, "socket_new() failed: %s", error->message); g_error_free (error); return FALSE; } bind_error: { GST_ERROR_OBJECT (self, "bind failed: %s", error->message); g_error_free (error); g_object_unref (socket); return FALSE; } getsockname_error: { GST_ERROR_OBJECT (self, "get_local_address() failed: %s", error->message); g_error_free (error); g_object_unref (socket); return FALSE; } failed_to_resolve: { GST_ERROR_OBJECT (self, "resolving '%s' failed: %s", self->address, err->message); g_clear_error (&err); g_object_unref (resolver); return FALSE; } no_thread: { GST_ERROR_OBJECT (self, "could not create thread: %s", error->message); g_object_unref (self->servaddr); self->servaddr = NULL; g_object_unref (self->socket); self->socket = NULL; g_error_free (error); return FALSE; } } static void gst_net_client_internal_clock_stop (GstNetClientInternalClock * self) { if (self->thread == NULL) return; GST_INFO_OBJECT (self, "stopping..."); g_cancellable_cancel (self->cancel); g_thread_join (self->thread); self->thread = NULL; if (self->made_cancel_fd) g_cancellable_release_fd (self->cancel); g_object_unref (self->cancel); self->cancel = NULL; g_object_unref (self->servaddr); self->servaddr = NULL; g_object_unref (self->socket); self->socket = NULL; GST_INFO_OBJECT (self, "stopped"); } struct _GstNetClientClockPrivate { GstClock *internal_clock; GstClockTime roundtrip_limit; GstClockTime minimum_update_interval; GstClockTime base_time, internal_base_time; gchar *address; gint port; gint qos_dscp; GstBus *bus; gboolean is_ntp; gulong synced_id; }; G_DEFINE_TYPE_WITH_PRIVATE (GstNetClientClock, gst_net_client_clock, GST_TYPE_SYSTEM_CLOCK); static void gst_net_client_clock_finalize (GObject * object); static void gst_net_client_clock_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec); static void gst_net_client_clock_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec); static void gst_net_client_clock_constructed (GObject * object); static GstClockTime gst_net_client_clock_get_internal_time (GstClock * clock); static void gst_net_client_clock_class_init (GstNetClientClockClass * klass) { GObjectClass *gobject_class; GstClockClass *clock_class; gobject_class = G_OBJECT_CLASS (klass); clock_class = GST_CLOCK_CLASS (klass); gobject_class->finalize = gst_net_client_clock_finalize; gobject_class->get_property = gst_net_client_clock_get_property; gobject_class->set_property = gst_net_client_clock_set_property; gobject_class->constructed = gst_net_client_clock_constructed; g_object_class_install_property (gobject_class, PROP_ADDRESS, g_param_spec_string ("address", "address", "The IP address of the machine providing a time server", DEFAULT_ADDRESS, G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS)); g_object_class_install_property (gobject_class, PROP_PORT, g_param_spec_int ("port", "port", "The port on which the remote server is listening", 0, G_MAXUINT16, DEFAULT_PORT, G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS)); g_object_class_install_property (gobject_class, PROP_BUS, g_param_spec_object ("bus", "bus", "A GstBus on which to send clock status information", GST_TYPE_BUS, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)); /** * GstNetClientInternalClock::round-trip-limit: * * Maximum allowed round-trip for packets. If this property is set to a nonzero * value, all packets with a round-trip interval larger than this limit will be * ignored. This is useful for networks with severe and fluctuating transport * delays. Filtering out these packets increases stability of the synchronization. * On the other hand, the lower the limit, the higher the amount of filtered * packets. Empirical tests are typically necessary to estimate a good value * for the limit. * If the property is set to zero, the limit is disabled. * * Since: 1.4 */ g_object_class_install_property (gobject_class, PROP_ROUNDTRIP_LIMIT, g_param_spec_uint64 ("round-trip-limit", "round-trip limit", "Maximum tolerable round-trip interval for packets, in nanoseconds " "(0 = no limit)", 0, G_MAXUINT64, DEFAULT_ROUNDTRIP_LIMIT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)); g_object_class_install_property (gobject_class, PROP_MINIMUM_UPDATE_INTERVAL, g_param_spec_uint64 ("minimum-update-interval", "minimum update interval", "Minimum polling interval for packets, in nanoseconds" "(0 = no limit)", 0, G_MAXUINT64, DEFAULT_MINIMUM_UPDATE_INTERVAL, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)); g_object_class_install_property (gobject_class, PROP_BASE_TIME, g_param_spec_uint64 ("base-time", "Base Time", "Initial time that is reported before synchronization", 0, G_MAXUINT64, DEFAULT_BASE_TIME, G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS)); g_object_class_install_property (gobject_class, PROP_INTERNAL_CLOCK, g_param_spec_object ("internal-clock", "Internal Clock", "Internal clock that directly slaved to the remote clock", GST_TYPE_CLOCK, G_PARAM_READABLE | G_PARAM_STATIC_STRINGS)); g_object_class_install_property (gobject_class, PROP_QOS_DSCP, g_param_spec_int ("qos-dscp", "QoS diff srv code point", "Quality of Service, differentiated services code point (-1 default)", -1, 63, DEFAULT_QOS_DSCP, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)); clock_class->get_internal_time = gst_net_client_clock_get_internal_time; } static void gst_net_client_clock_init (GstNetClientClock * self) { GstNetClientClockPrivate *priv; GstClock *clock; self->priv = priv = gst_net_client_clock_get_instance_private (self); GST_OBJECT_FLAG_SET (self, GST_CLOCK_FLAG_CAN_SET_MASTER); GST_OBJECT_FLAG_SET (self, GST_CLOCK_FLAG_NEEDS_STARTUP_SYNC); priv->port = DEFAULT_PORT; priv->address = g_strdup (DEFAULT_ADDRESS); priv->qos_dscp = DEFAULT_QOS_DSCP; priv->roundtrip_limit = DEFAULT_ROUNDTRIP_LIMIT; priv->minimum_update_interval = DEFAULT_MINIMUM_UPDATE_INTERVAL; clock = gst_system_clock_obtain (); priv->base_time = DEFAULT_BASE_TIME; priv->internal_base_time = gst_clock_get_time (clock); gst_object_unref (clock); } /* Must be called with clocks_lock */ static void update_clock_cache (ClockCache * cache) { GstClockTime roundtrip_limit = 0, minimum_update_interval = 0; GList *l, *busses = NULL; gint qos_dscp = DEFAULT_QOS_DSCP; GST_OBJECT_LOCK (cache->clock); g_list_free_full (GST_NET_CLIENT_INTERNAL_CLOCK (cache->clock)->busses, (GDestroyNotify) gst_object_unref); for (l = cache->clocks; l; l = l->next) { GstNetClientClock *clock = l->data; if (clock->priv->bus) busses = g_list_prepend (busses, gst_object_ref (clock->priv->bus)); if (roundtrip_limit == 0) roundtrip_limit = clock->priv->roundtrip_limit; else roundtrip_limit = MAX (roundtrip_limit, clock->priv->roundtrip_limit); if (minimum_update_interval == 0) minimum_update_interval = clock->priv->minimum_update_interval; else minimum_update_interval = MIN (minimum_update_interval, clock->priv->minimum_update_interval); qos_dscp = MAX (qos_dscp, clock->priv->qos_dscp); } GST_NET_CLIENT_INTERNAL_CLOCK (cache->clock)->busses = busses; GST_NET_CLIENT_INTERNAL_CLOCK (cache->clock)->roundtrip_limit = roundtrip_limit; GST_NET_CLIENT_INTERNAL_CLOCK (cache->clock)->minimum_update_interval = minimum_update_interval; GST_NET_CLIENT_INTERNAL_CLOCK (cache->clock)->qos_dscp = qos_dscp; GST_OBJECT_UNLOCK (cache->clock); } static gboolean remove_clock_cache (GstClock * clock, GstClockTime time, GstClockID id, gpointer user_data) { ClockCache *cache = user_data; G_LOCK (clocks_lock); if (!cache->clocks) { gst_clock_id_unref (cache->remove_id); gst_object_unref (cache->clock); clocks = g_list_remove (clocks, cache); g_free (cache); } G_UNLOCK (clocks_lock); return TRUE; } static void gst_net_client_clock_finalize (GObject * object) { GstNetClientClock *self = GST_NET_CLIENT_CLOCK (object); GList *l; if (self->priv->synced_id) g_signal_handler_disconnect (self->priv->internal_clock, self->priv->synced_id); self->priv->synced_id = 0; G_LOCK (clocks_lock); for (l = clocks; l; l = l->next) { ClockCache *cache = l->data; if (cache->clock == self->priv->internal_clock) { cache->clocks = g_list_remove (cache->clocks, self); if (cache->clocks) { update_clock_cache (cache); } else { GstClock *sysclock = gst_system_clock_obtain (); GstClockTime time = gst_clock_get_time (sysclock) + 60 * GST_SECOND; cache->remove_id = gst_clock_new_single_shot_id (sysclock, time); gst_clock_id_wait_async (cache->remove_id, remove_clock_cache, cache, NULL); gst_object_unref (sysclock); } break; } } G_UNLOCK (clocks_lock); g_free (self->priv->address); self->priv->address = NULL; if (self->priv->bus != NULL) { gst_object_unref (self->priv->bus); self->priv->bus = NULL; } G_OBJECT_CLASS (gst_net_client_clock_parent_class)->finalize (object); } static void gst_net_client_clock_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) { GstNetClientClock *self = GST_NET_CLIENT_CLOCK (object); gboolean update = FALSE; switch (prop_id) { case PROP_ADDRESS: GST_OBJECT_LOCK (self); g_free (self->priv->address); self->priv->address = g_value_dup_string (value); if (self->priv->address == NULL) self->priv->address = g_strdup (DEFAULT_ADDRESS); GST_OBJECT_UNLOCK (self); break; case PROP_PORT: GST_OBJECT_LOCK (self); self->priv->port = g_value_get_int (value); GST_OBJECT_UNLOCK (self); break; case PROP_ROUNDTRIP_LIMIT: GST_OBJECT_LOCK (self); self->priv->roundtrip_limit = g_value_get_uint64 (value); GST_OBJECT_UNLOCK (self); update = TRUE; break; case PROP_MINIMUM_UPDATE_INTERVAL: GST_OBJECT_LOCK (self); self->priv->minimum_update_interval = g_value_get_uint64 (value); GST_OBJECT_UNLOCK (self); update = TRUE; break; case PROP_BUS: GST_OBJECT_LOCK (self); if (self->priv->bus) gst_object_unref (self->priv->bus); self->priv->bus = g_value_dup_object (value); GST_OBJECT_UNLOCK (self); update = TRUE; break; case PROP_BASE_TIME:{ GstClock *clock; self->priv->base_time = g_value_get_uint64 (value); clock = gst_system_clock_obtain (); self->priv->internal_base_time = gst_clock_get_time (clock); gst_object_unref (clock); break; } case PROP_QOS_DSCP: GST_OBJECT_LOCK (self); self->priv->qos_dscp = g_value_get_int (value); GST_OBJECT_UNLOCK (self); update = TRUE; break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } if (update && self->priv->internal_clock) { GList *l; G_LOCK (clocks_lock); for (l = clocks; l; l = l->next) { ClockCache *cache = l->data; if (cache->clock == self->priv->internal_clock) { update_clock_cache (cache); } } G_UNLOCK (clocks_lock); } } static void gst_net_client_clock_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec) { GstNetClientClock *self = GST_NET_CLIENT_CLOCK (object); switch (prop_id) { case PROP_ADDRESS: GST_OBJECT_LOCK (self); g_value_set_string (value, self->priv->address); GST_OBJECT_UNLOCK (self); break; case PROP_PORT: g_value_set_int (value, self->priv->port); break; case PROP_ROUNDTRIP_LIMIT: GST_OBJECT_LOCK (self); g_value_set_uint64 (value, self->priv->roundtrip_limit); GST_OBJECT_UNLOCK (self); break; case PROP_MINIMUM_UPDATE_INTERVAL: GST_OBJECT_LOCK (self); g_value_set_uint64 (value, self->priv->minimum_update_interval); GST_OBJECT_UNLOCK (self); break; case PROP_BUS: GST_OBJECT_LOCK (self); g_value_set_object (value, self->priv->bus); GST_OBJECT_UNLOCK (self); break; case PROP_BASE_TIME: g_value_set_uint64 (value, self->priv->base_time); break; case PROP_INTERNAL_CLOCK: g_value_set_object (value, self->priv->internal_clock); break; case PROP_QOS_DSCP: GST_OBJECT_LOCK (self); g_value_set_int (value, self->priv->qos_dscp); GST_OBJECT_UNLOCK (self); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } } static void gst_net_client_clock_synced_cb (GstClock * internal_clock, gboolean synced, GstClock * self) { gst_clock_set_synced (self, synced); } static void gst_net_client_clock_constructed (GObject * object) { GstNetClientClock *self = GST_NET_CLIENT_CLOCK (object); GstClock *internal_clock; GList *l; ClockCache *cache = NULL; G_OBJECT_CLASS (gst_net_client_clock_parent_class)->constructed (object); G_LOCK (clocks_lock); for (l = clocks; l; l = l->next) { ClockCache *tmp = l->data; GstNetClientInternalClock *internal_clock = GST_NET_CLIENT_INTERNAL_CLOCK (tmp->clock); if (strcmp (internal_clock->address, self->priv->address) == 0 && internal_clock->port == self->priv->port) { cache = tmp; if (cache->remove_id) { gst_clock_id_unschedule (cache->remove_id); cache->remove_id = NULL; } break; } } if (!cache) { cache = g_new0 (ClockCache, 1); cache->clock = g_object_new (GST_TYPE_NET_CLIENT_INTERNAL_CLOCK, "address", self->priv->address, "port", self->priv->port, "is-ntp", self->priv->is_ntp, NULL); gst_object_ref_sink (cache->clock); clocks = g_list_prepend (clocks, cache); /* Not actually leaked but is cached for a while before being disposed, * see gst_net_client_clock_finalize, so pretend it is to not confuse * tests. */ GST_OBJECT_FLAG_SET (cache->clock, GST_OBJECT_FLAG_MAY_BE_LEAKED); } cache->clocks = g_list_prepend (cache->clocks, self); GST_OBJECT_LOCK (cache->clock); if (gst_clock_is_synced (cache->clock)) gst_clock_set_synced (GST_CLOCK (self), TRUE); self->priv->synced_id = g_signal_connect (cache->clock, "synced", G_CALLBACK (gst_net_client_clock_synced_cb), self); GST_OBJECT_UNLOCK (cache->clock); G_UNLOCK (clocks_lock); self->priv->internal_clock = internal_clock = cache->clock; /* all systems go, cap'n */ } static GstClockTime gst_net_client_clock_get_internal_time (GstClock * clock) { GstNetClientClock *self = GST_NET_CLIENT_CLOCK (clock); if (!gst_clock_is_synced (self->priv->internal_clock)) { GstClockTime now = gst_clock_get_internal_time (self->priv->internal_clock); return gst_clock_adjust_with_calibration (self->priv->internal_clock, now, self->priv->internal_base_time, self->priv->base_time, 1, 1); } return gst_clock_get_time (self->priv->internal_clock); } /** * gst_net_client_clock_new: * @name: a name for the clock * @remote_address: the address or hostname of the remote clock provider * @remote_port: the port of the remote clock provider * @base_time: initial time of the clock * * Create a new #GstNetClientInternalClock that will report the time * provided by the #GstNetTimeProvider on @remote_address and * @remote_port. * * Returns: (transfer full): a new #GstClock that receives a time from the remote * clock. */ GstClock * gst_net_client_clock_new (const gchar * name, const gchar * remote_address, gint remote_port, GstClockTime base_time) { GstClock *ret; g_return_val_if_fail (remote_address != NULL, NULL); g_return_val_if_fail (remote_port > 0, NULL); g_return_val_if_fail (remote_port <= G_MAXUINT16, NULL); g_return_val_if_fail (base_time != GST_CLOCK_TIME_NONE, NULL); ret = g_object_new (GST_TYPE_NET_CLIENT_CLOCK, "name", name, "address", remote_address, "port", remote_port, "base-time", base_time, NULL); /* Clear floating flag */ gst_object_ref_sink (ret); return ret; } G_DEFINE_TYPE (GstNtpClock, gst_ntp_clock, GST_TYPE_NET_CLIENT_CLOCK); static void gst_ntp_clock_class_init (GstNtpClockClass * klass) { } static void gst_ntp_clock_init (GstNtpClock * self) { GST_NET_CLIENT_CLOCK (self)->priv->is_ntp = TRUE; } /** * gst_ntp_clock_new: * @name: a name for the clock * @remote_address: the address or hostname of the remote clock provider * @remote_port: the port of the remote clock provider * @base_time: initial time of the clock * * Create a new #GstNtpClock that will report the time provided by * the NTPv4 server on @remote_address and @remote_port. * * Returns: (transfer full): a new #GstClock that receives a time from the remote * clock. * * Since: 1.6 */ GstClock * gst_ntp_clock_new (const gchar * name, const gchar * remote_address, gint remote_port, GstClockTime base_time) { GstClock *ret; g_return_val_if_fail (remote_address != NULL, NULL); g_return_val_if_fail (remote_port > 0, NULL); g_return_val_if_fail (remote_port <= G_MAXUINT16, NULL); g_return_val_if_fail (base_time != GST_CLOCK_TIME_NONE, NULL); ret = g_object_new (GST_TYPE_NTP_CLOCK, "name", name, "address", remote_address, "port", remote_port, "base-time", base_time, NULL); gst_object_ref_sink (ret); return ret; }