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Questions related to the asFFT Xtra 
framerate asFFT needs dir to run at to be accurate?
Posted by: kyleg ()
Date: December 18, 2009 09:26PM

testing out the plugin and I must say, its pretty cool. I am wanting to play audio and launch an action based on the id of the sound at a particular second/frame in time.

I am able to play the sound and capture the values for 3 bands of EQ (bins) and then successfully play it back and execute my trigger when it hears that frequency played back.

The problem is that this only works with 3 bins. and only 60% of the time. Other times it misses the mark. I rather query 15-20 bin samples to be very accurate.

To get it to work at all I also must have normalized and equalized set (which is fine).

For what I am doing I must run the project at 25FPS. Is this one of the reasons I am not able to do much past 3 bins? I tried speeding the FPS up so that when looping it is checking faster, but does not seem to matter.

Do you have any suggestions to improve the recognition of more then 3 frequencies. tried increasing time smoothing but did not help...but maybe I need to try that more? This may be a limitation of lingo not processing fast enough? processing sound level works really well , but not as accurate as FFT

thanks

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Re: framerate asFFT needs dir to run at to be accurate?
Posted by: antoine schmitt ()
Date: December 18, 2009 09:44PM

Hi,
I'm not sure that I understand what you are doing exactly, but I think the variation of the framerate is probably the problem : each time you run your animation (playing the sound and computing the FFTs and comparing), the frames do not happen at the same moments because the framerate is not stable. The framerate is just an indication for director to do as well as it can, but depending on what the computer is doing at the same moment there will be slight variations.
To improve your recognition, you should take this into account, and for example allow for an imprecision in the comparisons of the frequency patterns. Like "equal within 5%". Something like this..
I hope this helps..

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Re: framerate asFFT needs dir to run at to be accurate?
Posted by: kyleg ()
Date: December 21, 2009 02:52AM

Thanks...I also saw the igor plugin but that to depends on the framerate I believe. I will try the 5% and see if I can improve the accuracy. Yes director frames do tend to be a best it can effort on the software.

Kyle

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