[gst-devel] Timestamping and clocking compared to DirectShow

[Tim Harris]

Hi All,
I'm wondering how close Gstreamer's clocking/timestamping features are
to those in DirectShow.

From the Plug-in Writer's Manual the description makes the mechanisms
sound very similar with a couple exceptions:
1) The event time (timestamp relative to global clock, AKA presentation
time) doesn't necessarily start at 0 in GStreamer.
2) There is no "media time" equivalent in Gstreamer (e.g. frame/sample
number in the stream, which isn't reset on seek). Used to detect dropped
frames/samples.

The documentation around clocking isn't very clear. Does the GStreamer
core pick one global clock which is accessed by all of the elements, or
do the elements only ever access the element time through Gstreamer and
use their own global clock? What is the timebase of the global/element
clocks and the timestamps?

Gstreamer looks like a cool project. Keep up the good work.

Thanks,
Tim

P.S.
Does anyone have links to any papers referring to OGI's video pipeline
mentioned as the inspiration for Gstreamer. Unfortunately their group's
webpage seems to be suffering from a MySQL crash.

--
Tim Harris
EngD Research Engineer
tim.harris at snellwilcox.com

Snell & Wilcox Ltd.
www.snellwilcox.com

Institute For System Level Integration
www.sli-institute.ac.uk

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