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netclock: Don't update the clock when it desynch

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Add a hold off when the clock calibration suddenly loses synch,
as it may be a glitch, but also make sure we update if it stays
desynched for more than a few seconds
This commit is contained in:
Jan Schmidt 2015-02-07 04:22:22 +11:00
parent 824b821caa
commit f0e3b7f904
1 changed files with 42 additions and 13 deletions
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55
libs/gst/net/gstnetclientclock.c
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@ -71,6 +71,9 @@ GST_DEBUG_CATEGORY_STATIC (ncc_debug);
* more often than 1/20th second (arbitrarily, to spread observations a little) */
#define DEFAULT_MINIMUM_UPDATE_INTERVAL (GST_SECOND / 20)
/* Maximum number of clock updates we can skip before updating */
#define MAX_SKIPPED_UPDATES 5
enum
{
PROP_0,
@ -96,6 +99,7 @@ struct _GstNetClientClockPrivate
GstClockTime roundtrip_limit;
GstClockTime rtt_avg;
GstClockTime minimum_update_interval;
guint skipped_updates;
gchar *address;
gint port;
@ -189,6 +193,7 @@ gst_net_client_clock_init (GstNetClientClock * self)
priv->rtt_avg = GST_CLOCK_TIME_NONE;
priv->roundtrip_limit = DEFAULT_ROUNDTRIP_LIMIT;
priv->minimum_update_interval = DEFAULT_MINIMUM_UPDATE_INTERVAL;
priv->skipped_updates = 0;
}
static void
@ -306,7 +311,7 @@ gst_net_client_clock_observe_times (GstNetClientClock * self,
GstClockTime local_1, GstClockTime remote, GstClockTime local_2)
{
GstNetClientClockPrivate *priv = self->priv;
GstClockTime current_timeout;
GstClockTime current_timeout = 0;
GstClockTime local_avg;
gdouble r_squared;
GstClock *clock;
@ -316,8 +321,10 @@ gst_net_client_clock_observe_times (GstNetClientClock * self,
GstClockTime time_before = 0;
GstClockTime min_guess = 0;
GstClockTimeDiff time_discont = 0;
gboolean synched;
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;
GST_OBJECT_LOCK (self);
@ -369,8 +376,12 @@ gst_net_client_clock_observe_times (GstNetClientClock * self,
clock = GST_CLOCK_CAST (self);
/* Store what the clock produced as 'now' before this update */
gst_clock_get_calibration (GST_CLOCK (self), &internal_time, &external_time,
&rate_num, &rate_den);
gst_clock_get_calibration (GST_CLOCK (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 (self), local_1,
@ -383,7 +394,7 @@ gst_net_client_clock_observe_times (GstNetClientClock * self,
* but this value seems to work fine */
max_discont = priv->rtt_avg / 4;
/* If the remote observation was within 1/4 RTT of our min/max estimates, we're synched */
/* If the remote observation was within a max_discont window around our min/max estimates, we're synched */
synched =
(GST_CLOCK_DIFF (remote, min_guess) < (GstClockTimeDiff) (max_discont)
&& GST_CLOCK_DIFF (time_before,
@ -420,15 +431,33 @@ gst_net_client_clock_observe_times (GstNetClientClock * self,
time_discont += offset;
}
gst_clock_set_calibration (GST_CLOCK (self), internal_time, external_time,
rate_num, rate_den);
/* Check if the new clock params would have made our observation within range */
now_synched =
(GST_CLOCK_DIFF (remote,
gst_clock_adjust_with_calibration (GST_CLOCK (self), local_1,
internal_time, external_time, rate_num,
rate_den)) < (GstClockTimeDiff) (max_discont))
&& (GST_CLOCK_DIFF (gst_clock_adjust_with_calibration (GST_CLOCK (self),
local_2, internal_time, external_time, rate_num, rate_den),
remote) < (GstClockTimeDiff) (max_discont));
/* 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 (clock));
} else {
/* No correlation, short timeout when starting up or lost sync */
current_timeout = 0;
/* Only update the clock if we had synch or just gained it */
if (synched || now_synched || priv->skipped_updates > MAX_SKIPPED_UPDATES) {
gst_clock_set_calibration (GST_CLOCK (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 (clock));
priv->skipped_updates = 0;
} 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;
priv->skipped_updates++;
}
}
/* Limit the polling to at most one per minimum_update_interval */