[vlc-devel] why netsync unicast?

Gildas Bazin gbazin at altern.org
Thu Dec 6 20:00:59 CET 2007


On Thu, 2007-12-06 at 19:39 +0200, Rémi Denis-Courmont wrote:
> Le Thursday 06 December 2007 09:39:08 Ryan Nowakowski, vous avez écrit :
> > Is there any reason why netsync uses udp unicast?  It seems like a
> > perfect application for multicast!  It would scale better that way.
> 
> I may be wrong, but I think it could use multicast by simply putting a 
> multicast address in the configuration.
> 

The reason for using multicast is that we try to evaluate the latency
introduced by the network to compensate the master clock ticks that we
receive. With multicast you would not be able to do that.
Now it probably is debatable whether or not this actually matters on a
LAN so we could probably also implement a multicast version.

> Of course, the real problem is that netsync is fairly broken and unmaintained 
> at the moment.
> 

The only problematic part in netsync is GetClockRef() since it uses a
bit of a hack to access the reference clock of the input. Once this is
fixed netsync will work again. Maybe fenrir could give us some pointer
on how this would be best fixed ?

Cheers,

--
Gildas




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