Forums > Jitter

still frame on screen using jit.qt.grab

March 22, 2007 | 4:48 pm

I am trying to put a still frame from a camera in a jit window at periodic intervals.

I have tried sending the jit.qt.grab object a bang, but the frame that gets output is not the current frame – it is a frame from a short time after the last bang – it is always on bang behind.

If i’m in shot, I bang to show the picture then move out of shot, bang again and I still show (but the picture changes), bang again and I am gone.

Is there another way I should be trying to do this.

I have tried using trigger to send b b in quick succesion but that doesn’t work either.

Any ideas?

Cheers

Nick


March 22, 2007 | 4:56 pm

On Mar 22, 2007, at 9:48 AM, nick wrote:

>
> I am trying to put a still frame from a camera in a jit window at
> periodic intervals.
>
> I have tried sending the jit.qt.grab object a bang, but the frame
> that gets output is not the current frame – it is a frame from a
> short time after the last bang – it is always on bang behind.

Sounds like you need to bang the camera regularly (say 30fps or
faster) to service the queue of frames the camera wants to deliver.
You can then cache in jit.matrix @thru 0 and bang jit.matrix instead.
If that still doesn’t work, it’s general camera latency which you’ll
need to account for with a delay object or something which counts
frames.

-Joshua


March 22, 2007 | 5:20 pm

that works perfectly

thanks for quick reply!

I had tried going through a matrix, but hadn’t got the @thru 0 set which of course makes all the difference.

Cheers

Nick


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