Re: [Jack-Devel] Variable delay line problem

Chris Caudle schrieb am 13.04.2012 23:29:
> On Fri, April 13, 2012 11:52 am, Stéphane VAXELAIRE wrote:
>> Thanks, I did try that, but when I do, the sine does not seem to evolve.
>
> Maybe I suggested the division in the incorrect location.
> I tried the equivalent in Octave, and it seems to work with:
> cos(n/Fs*2*pi*freq)
>
> I don't remember how operator order of precedence works in Octave, so I
> also tried:
> cos(2*pi*n*(freq/sample_rate))
>
> and that also seemed to work like expected.
>
> By work as expected, I just mean it generated cosine values of the
> expected period.  I did not try to actually implement a variable delay so
> that I could make a flanger in Octave code.
>

If you are looking for a flanger implemented in Matlab (most probably 
works with litte or no changes also in Octave) you may take a look at e.g.
http://www.mathworks.com/matlabcentral/fileexchange/6656-flange-effect

or this nice presentation containing flanger Matlab code as well:

http://www.cs.cf.ac.uk/Dave/CM0268/PDF/10_CM0268_Audio_FX.pdf

or in general:

http://www.google.com/search?q=flanger+octave+OR+matlab

> Are you doing any prototype code in Octave, or is everything in C?
>
> Also, I didn't really pay attention to how you were implementing the
> delay.  I had assumed you would do an interpolated delay so you can make
> smooth phase adjustments.  If you are just grabbing samples from the delay
> buffer, you are going to have discontinuous jumps between samples, and
> that is going to sound really bad, just like having lots of under-runs
> (same effect, you are just skipping over some samples and not playing
> them).
>

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