With standard DV input the performance is fine, but the app does
use about 30-40% of the processor's on a Dual G5 2.0. However I am
also trying to make the app work with a DVCPRO HD input which is a
much more processor intensive codec and the performance for this is
unusable.
Try changing the settings on the video capture patch with the
Inspector: "High quality" and also the device settings especially the
codec that is used
Also keep your composition super-simple for now: just a video capture
patch and a billboard
In reading on a bit further, it seems that what I should do now is
to use QC Renderer to play the composition. Does this allow greater
performance with the overlay as its using an 'OpenGL context'?
You don't have to: QCRenderer is mostly for people who want to do low-
level integration of the QC engine within their app
Alternatively, perhaps I should be using QTKit instead of a Quartz
Composition - the main features must allow live preview of firewire
video input, allow real time 180 degree rotation and real time de-
saturation. There are a few other features I want to implement such
as being able to scale without loosing aspect ratio and also make
fullscreen, but for now the main objective is to solve the
performance issue.
I don't if you can do video capture with QTKit, but you can give it a
shot
________________________________________________________
Pierre-Olivier Latour email@hidden
Quartz Composer Team Apple Computer, Inc.
