[MPlayer-users] feature requests

[D Richard Felker III]

On Mon, Mar 21, 2005 at 10:04:43PM -0600, Bret Hughes wrote:
> On Mon, 2005-03-21 at 17:32, Thomas Martinsen wrote:
> > Bohdan Horst wrote:
> > 
> > >Just curious - is there any way to synchronize two (or more) mplayers?
> > >(for example for watching movie with a friend on the other side of the
> > >world) 
> > >
> > >regards
> > >
> > >  
> > >
> > hahahah, what would be the use of this?
> > why dont you just start the movie at the same time? ;)
> > 
> 
> I could see this as being a really powerful tool for advertising based
> applications where multiple screens are available and at times you might
> want the same movie synced on all screens.
> 
> If a frame number sync could be done you could create virtual screens
> with multiple players each with part of the image on a high resolution
> projector.  even something that we mormally consider high res, say 1024
> X 768 starts looking sloppy at screen sizes greater than 60 inches or
> so. Imagine a 3x3 matrix with each player running a ninth of an ad built
> in illustrator or adobe after effects at 1024 x 768 projected on dnp
> holoscreens.  exhibitors and other show based advertisers would flip.
> 
> I have no idea how this would be accomplished. I have been thinking of a
> simple control script that would start a movies on multiple players that
> would allow chasing images to be synced very closely but have not
> started on the implementation yet.
> 
> There are lots of different applications once you get away from the I am
> sitting at this computer and want to watch a dvd mindset.

Without sound, this all is pretty easy. The problem is that mplayer
uses sound as the timer, and syncs video to the soundcard's rate of
playing the audio. Drift happens when there are minor differences (or
major, with the crappy soundcards sold today...) in the clocks on the
soundcards so they don't run at the exact samplerate, but 0.1-1.0% off
or something...

A good player would be able to sync to an external reference clock
(this is actually needed for watching streaming media, btw) and
dynamically resample the sound to correct for soundcard errors.
Unfortunately mplayer can't do this.

Rich