[MPlayer-dev-eng] Synchronization of players in LAN

[Attila Kinali]

On Thu, 20 Nov 2003 10:14:24 +0100
"J.A. Gutierrez" <spd at shiva.cps.unizar.es> wrote:

> 	I'm trying to synchronise several players running on several
> 	computers connected to a dedicated 10/100 Ethernet switch. Each
> 	one reads a different movie (video only) from its internal hard
> 	disk, and resolution will be 768x576.

Interesting idea, what do you want to achive ?

 
> 	I'm thinking of a simple solution:
> 
> 	- Add some code at mplayer startup so it will wait for an UDP
> 	broadcast packet (sent by a central master in the LAN). This
> 	way all the players would start at the same time.

Possible

> 	- Use NTP to keep in sync all the computers' clocks, and trust
> 	mplayer's rtc synchronisation feature.
> 

Mplayer does not sync against an external clock but syncs video to audio.
RTC is only used for sleeping, nothing more. See mplayer.c:2205

> 	With this simple setup, could we be sure all the players would
> 	keep the synchronisation? Or should the master computer track
> 	them all and take control on their speeds?

Wont work.

> 	How difficult would be to add code so all the player synchronise
> 	using the LAN? Or should I use some external clock connected to
> 	all serial ports? Or use a totally different approach?

You'd have to change mplayers sync code to sync against the system
clock (or anyother external source) instead of audio. 
Then you could work with ntp.


			Attila Kinali

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