Frame rate fluctuation & conversion

drshakamoto

Hi,
So I have two questions really

I am working on a patch that uses video delay/feedback from my computer webcam using jit.grab. I want to then use the intervals between the two video feeds to send a bang which I will use as a midi trigger. I worked out the rough interval between the feeds in sec/ms and created an equation to translate this into bangs.(this doesn't have to be exact just roughly accurate so the echo of image would reflect an echo in sound.

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However, I'm having a problem with framerate fluctuation. The output of jit.grab seems to fluctuate between 9-21 fps. Which means that the equations fails to reflect the delay. Some fluctuation is fine but such a big change throws it off. Is this normal?

A possible way around this is to convert the fps number into an integer/float and use it in the equation, so that when the framerate changes it will be incorporated into the delay-time equation. Is there a way to make this conversion?

Thanks,

Matteo Marson

Hey Finn,

you could try with something like this to compute the time interval between frames

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yaniki

It is rather simple to measure time between two events (for example frames in video stream):

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