OSC, delays and the conditional patch.

steve holmes's picture

Hi everyone as I have mentioned I am developing an art gallery piece that will play video feeds in sync across 21 screens in a gallery. The content is in many rooms spread across 3 floors of a large gallery. The content is footage of an orchestra shot with 21 HD cameras and will include the audio. The playback will be from MacPros that will drive 3 screens each using a triplhead2go. For each 3 screens there will only be one stereo sound track to keep the audio simple. Because there is audio it is important to have the sync as close as possible, but at the same time there will only be one stereo source per room so there may be room for 1-2 frames out.

The basic control is a master computer that plays a video file using vade's V002 movie player, then using a conditional patch on current time and movie duration it triggers the file to play again using the reset. The reset signal is sent through OSC (on to the other computers using a gigabit switch. The current test setup I have is MacBook Pro as master computer and a MacPro as slave machine playing back 3 files.

Using my Sony EX1 filming at 50p I can monitor the output of the MacBook Pro and the MacPro I can see that the slave machine is between 2-10 frames behind. I have tried to solve this by adding a short delay to the master computer reset but the virtual delay patch seems to be random in its accuracy. The delay patch uses a stop watch and a conditional patch with variable tolerance.

I am just wondering if there is a different more accurate way of adding a 1 to 10 frames of delay which is between 0.04 and 0.4 of a second. And if anyway has any other ideas on driving this system. Cheers Steve