[Bug 785733] New: rtpbin: ntp-sync does no sanity checking for clock sync
GStreamer (GNOME Bugzilla)
bugzilla at gnome.org
Wed Aug 2 13:34:45 UTC 2017
https://bugzilla.gnome.org/show_bug.cgi?id=785733
Bug ID: 785733
Summary: rtpbin: ntp-sync does no sanity checking for clock
sync
Classification: Platform
Product: GStreamer
Version: git master
OS: Linux
Status: NEW
Severity: normal
Priority: Normal
Component: gst-plugins-good
Assignee: gstreamer-bugs at lists.freedesktop.org
Reporter: patrick.radizi at axis.com
QA Contact: gstreamer-bugs at lists.freedesktop.org
GNOME version: ---
The ntp-sync parameter of rtpbin synchronizes received streams based on the
assumption that sender and receiver clocks are in sync. If they are not, an
arbitrarily large time offset can be applied to each received buffer. Since NTP
can take quite some time before all clocks are in sync, this leads to corrupt
timestamps before all clocks have 'settled' in.
A sanity check of the calculated time offset is thus needed. If to large it
would be better to simply skip the offset.
Furthermore, currently a positive time offset might be applied. But if a
positive offset is calculated it must mean that the clocks are not in sync. A
buffer will obviously always arrive 'late' at the receiver, so to get its
creation time we need to remove, not add time.
A timestamp offset sanity check could be
if (ts_offset < 0 && > -SOME_LIMIT)
apply offset
else
skip offset
When synchronizing streams without ntp the rtpbin currently does a sanity check
and it will not apply an offset larger than 3 sec.
--
You are receiving this mail because:
You are the QA Contact for the bug.
You are the assignee for the bug.
More information about the gstreamer-bugs
mailing list