[QLab] recommended system configuration for video / best practices?

[Christopher Ashworth]

On Nov 27, 2007, at 12:26 AM, Dan Scully wrote:
>
> Also, I was looking to sum up the tips I've seen for optimizing video
> playback on this list:
>
> 1) Match output resolution to image resolution

I'd shift the focus more to the final image resolution.  It's okay to  
have mismatched resolutions, but you don't want to try to drive a  
bigger projection/display resolution than your graphics card can handle.

> 3) Format: Animation or Motion-JPG

Because animation is a low-compression or no-compression format, it  
leads to high disk demands and therefore can easily bottleneck at the  
disk.

I believe in the past the animation codec was mentioned because it  
(bizarrely) has been able to bypass the bug that prevents multiple  
graphics cards from being use on Quicktime 7.2 and later.  I haven't  
tested it for this property recently, however, and don't necessarily  
recommend it because of the disk throughput requirements.


A general note on file formats:

There seems to be a desire to find the "perfect" file format.  I'd  
encourage folks to step back from that desire a little bit.  I think  
it's more helpful to think in terms of basic theory:  uncompressed and  
low-compressed formats will require high disk performance, while  
compressed formats will require more work from the CPU/GPU.  There are  
a number of file formats supported by Quicktime that can be useful and  
perform roughly the same.   Video playback will always involve  
balancing CPU, GPU, and hard disk, and the degree to which these  
factors will interact depends on what media you're trying to display,  
the size of your projection/display surface, etc.  Thus there is not  
generally one "best" configuration for everybody.  If you're concerned  
about a particular format, fire up Activity Monitor and see if your  
CPU is straining, or if your disk throughput is exceptionally high.   
Balance as necessary.

Cheers,
Christopher