I'm working on a project in which it is critical to record two
identical firewire cameras (like isights) in synchrony in an
eyetracking application. We capture one view of the eye and one of
the scene, and by combining information from both cameras we know
where the eye is pointing relative to the scene (rather than just
relative to the head).
One way we've looked into this issue is to use WhackedTV. It allows
simultaneous recording of two video sources, but right now it puts
both images on top of each other in the same file. This can be seen
if one image is slightly larger than the other (I was using a
handicam and an isight).
If we could offset the two images and store them side-by-side we
could be certain that the two cameras were always aligned in time.
However, if I change the port sizes of the seqgrab, it just
stretches the images. Is there a way to create a seqgrab port that
is something like 1280 x 480, and put two 640x480 images side by side?
One simple way to do this would be to post-process the movie after
the grab is done. After you SGStop(), you can use SGGetMovie() to
get a reference to the Movie file that was created. Then find the
track you're interested in with GetMovieTrackCount()/GetMovieTrack
(). Once you find it, you can offset it using a matrix with
SetTrackMatrix().
-Brad Ford
QuickTime Engineering
An alternative would be to record to two separate files and then
verify that they were aligned in time.
I'd appreciate any help from the list. I am a subscriber, so feel
free to respond to the list, or email me below. The eyetracker is
described at:
Associate Professor of Psychological and Brain Sciences
Indiana University, Bloomington, IN
www.indiana.edu/~busey
busey$indiana.edu (replace $ with what normally goes there)
_______________________________________________
Do not post admin requests to the list. They will be ignored.
QuickTime-API mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quicktime-api/email@hidden
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
QuickTime-API mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quicktime-api/email@hidden
