On 26 Oct 2008, at 22:53, Greg Best wrote:
Hello--
I can't find any documentation on how a queue works, exactly... It
takes a sequence of inputs, and outputs a structure. The patch
creator blurb says this is a FILO queue (which makes it more of a
stack than a queue?).
First question: when I access items from the structure at different
depths (indexes), am I popping off all of the items that I access,
or just the most recent? If difference the first and second members
of the structure, have I reduced the queue length by 1 or 2?
Reading items from the Queue has no effect on the length of the Queue
structure.
Second question: is there a FIFO available, as opposed to the FILO
queue? I'm not finding one...
No. But you can access the items in the Queue in reverse order.
Third question: aside from just wanting to know how these patches
work, I'm looking for away of comparing time separated frames from a
video input. In the simplest case, I'd like to be able to subtract
a video frame from the preceding frame (or a the frame that occurred
5 frames earlier).
Very easy.
Connect your image to the Queue.
Connect two Structure Index Member patches to the Queue's outport.
Set the index for the first Structure Index Member patch to 0 and the
2nd to 1.
The output of the first Structure Index Member patch will be the
newest image, and the 2nd will be the previous frame.
Use one of the Compositing patches to combine the 2 images.
Incidentally, you can use Queues for other kinds of data, too. They're
also very cool for control values.
Hope this helps,
a|x
http://machinedontcare.wordpress.com
Thanks--
Greg
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