[Live-devel] Local clock drift/offset compensation?

[Marian Durkovic]

On Mon, Nov 07, 2005 at 01:16:20AM -0800, Ross Finlayson wrote:
> 
> >Or is the mediaplayer supposed to
> >compensate for the offset/drift between the local clock and 
> >PresentationTime
> >as computed by liveMedia library?
> 
> Yes.

Well, but the mediaplayer does not have all the necessary information to
correctly compute the clock drift - for example, the real packet arrival
time is not known by the mediaplayer.

On the other hand, liveMedia library has all the info - RTP timestamps, RTCP
SRs as well as real packet arrival times. So computing the clock drift is much
easier in liveMedia library - and if the PresentationTime would be adjusted to
the local clock, the mediaplayer could use it without further processing.
I'm afraid that's what mediaplayers are doing now anyway since after 24
hours of playback there's a drift of several seconds.

Wouldn't it therefore make sense to implement this in liveMedia - perhaps
with an option to turn it on/off via some parameter?


	Thanks & kind regards,

		M.


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