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 averaging LPF
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cristian_vogel Member |
posted 08 August 2006 02:21
 
I have been experimenting with this sound, its quite interesting sonically - can you shed some more light on what it does, how it works and why you would use it? It doesnt sound like a normal LPF, its less accurate... Using a script and variable , I managed to make the Frequency field dynamic, but it usually gets too loud and clips if you start to move the LPF up above 1K - what explains that behaviour? IP: Logged |
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SSC Administrator |
posted 08 August 2006 08:17
AveragingLowPassFilter takes a running average of incoming samples (and sends the current result to the output on each sample). To see why averaging the samples would have a low-pass effect, imagine what happens at DC (a constant) when you take an average: nothing! DC (and low frequencies) pass through. Then think of what would happen at a sine wave whose period was the length of the average; since half of the sine wave is above zero and half of it is below zero, on average its value would be zero; that frequency and all its harmonics would be completely cancelled. So the frequency response is a kind of low pass filter with ripples. Another way to think of it is to imagine a quickly changing waveform (the quick changes correspond to high frequencies). Visually, if you average the waveform, you would expect the details to get smoothed out (removing the higher frequencies). The way the algorithm is implmented, it expects a constant cutoff frequency. It would have strange scaling effects if you change the cutoff (related to the length of the averaging time) while the Sound is playing. IP: Logged |
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Phi Curtis Member |
posted 09 August 2006 02:35
quote: Hi Cristian, Out of curiousity, could you tell how you did this? It sounds like a good trick. thanks, IP: Logged |
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