Accessing USB webcams in Rev on Mac

[Ben Rubinstein]

Using the revVideoGrab... functions  Rev 2.8.1 on Mac OS X, I can access an 
external firewire iSight camera; the 'Sources' tab on the dialog invoked by 
revVideoGrabSettings  also gives me a choice, greyed out, of a DV source.  On 
a machine with a built-in iSight camera, and an external one plugged in, I get 
to choose between the two cameras, and the disabled option of the DV source is 
still noted.

I plugged a USB webcam into my PowerBook, and installed macam with the 
quicktime component as a driver.  Now various apps that I've tried offer this 
as a source option.

But in the otherwise identical dialog presented in Rev, that option just 
doesn't appear in the 'Sources' tab.

The reason I wanted to use the inferior USB webcam was because I need to 
present, in my Rev stack, a video feed from 'the other direction' (the camera 
is point down at a table).  I don't have a long enough cable for my external 
iSight to put it on the other side of the table; but I do have a 16ft USB 
extension cable that would allow me to place a USB webcam appropriately.  But 
I couldn't make the USB cam work in Rev, though it worked in everything else. 
  Having failed to use the USB webcam, I then found a solution: to turn the 
feed from the iSight upside down.  This turned out to be achievable by making 
a quartz composer patch, exporting it as a QT movie, and then importing that 
movie into Rev.  That worked great.

But thinking about this, I thought I must have stumbled on a way to use the 
USB webcam anyway - use the same trick, so Rev just thinks it's playing a 
movie.   I tried it with my existing movie - no dice.  I then verified that 
Quartz Composer, like every other app apart from Rev, could see the USB 
webcam; made a new patch using it, and with a framerate display as well; 
exported to movie, imported to Rev.   When this new movie was started, the 
framerate display became active; but there was no image.  With iSight and USB 
webcam plugged in, it worked, but showed the image from the iSight.

So it would seem that whatever the problem is, it's perhaps rather indirect - 
Rev somehow disabling the USB webcam at a lower level rather than just not 
being prepared to use it.

(Extra input; I say every other app can see the USB cam; actually, with the QC 
movies, viewing them in QuickTime player shows USB or iSight feed; but doing 
'preview' in the Finder works like Rev: with the iSight plugged in, the feed 
appears; without it there's just the framerate display.)

Quelle bizarre.

Has anyone else had success (or failure) using Rev to access USB webcams on Mac?

TIA

- Ben