[music-dsp] Re: Wavelet Convolution

[Ken Noland]

Interesting!

Do many audio processors use the mel scale for finer selection in
specific frequency ranges? Seems very intuitive to increase scale on
audible portions for finer selection.

I find the usage of multiple transform windows very inefficient for what
I am doing, but very handy for what they are doing. After all, they
process their sounds in 64 bits, whereas I am limited to 16 bit
storage... obviously they are going for precision... I'm going for speed
and lower mem usage.

-Ken Noland



-----Original Message-----
From: music-dsp-bounces at music.columbia.edu
[mailto:music-dsp-bounces at music.columbia.edu] On Behalf Of Didier
Dambrin
Sent: Saturday, October 07, 2006 9:18 AM
To: A discussion list for music-related DSP
Subject: Re: [music-dsp] Re: Wavelet Convolution

Izotope did something related
http://www.izotope.com/tech/aes_adapt/

it's not exactly realtime enough for smooth zooming, though



>> Date: Sat, 7 Oct 2006 07:36:21 +0200
>> From: "Didier Dambrin" <didid at skynet.be>
>>
>> I think it would be helpful to see transients more accurately, while 
>> having more definition in the lower freqs.
>
> The time resolution is inversely proportional to the frequency
resolution, 
> so you can set things up so that there are an equal number of
frequency 
> bins per octave, so giving you higher time resolution at higher 
> frequencies.    In ASCII art here are three octaves:
>
> +-+-+-+-+-+-+-+-+
> | | | | | | | | |
> | | | | | | | | |
> | | | | | | | | |
> +-+-+-+-+-+-+-+-+
> | | | | | | | | |
> | | | | | | | | |
> | | | | | | | | |
> +---+---+---+---+
> |   |   |   |   |
> +---+---+---+---+
> |   |   |   |   |
> +-------+-------+
> +-------+-------+
> +-------+-------+
>
> This is the standard way to be able to see transients more accuractly 
> (through the time resolution at high frequencies), and you get better 
> frequency definitition at lower frequencies.
>
> I'd like to see something different.   If the signal is stationary I'd

> like to be able to see all the harmonics - e.g. via a long time period

> FFT, and if the signal isn't then I'd like to see the moment of
transition 
> (using short time period FFT).
>
> Anyone know of anything like this around?   I guess the implementation

> hinges on what I mean by stationary, I don't have a formal definition
just 
> now, but say if the spectral distortion of two FFTs of length T is
below 
> some threshold then they are replaced by one FFT of length 2T.
>
>
> Tony
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