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Re: audio problems


From: Paul Kienzle
Subject: Re: audio problems
Date: Tue, 11 Dec 2001 11:10:22 -0500

When you are downsampling, you will want to low-pass filter
your input first.  E.g., to downsample by a factor of q
  [b, a] = cheby1(n, 0.05, 1/q);
  y = filter(b,a,x);
  y = y(1:q:length(x));
The function cheby1 is available from octave-forge at octave.sf.net

Also, /dev/dsp may be expecting mulaw encoded data.
In that case you will need to do playaudio(lin2mu(y)).

Paul Kienzle
address@hidden

On Tue, Dec 11, 2001 at 06:50:55PM +1100, Matthew Flax wrote:
> Hi there,
> 
> I am just writing to let you know that the audio output is alwayse @ 8 
> bit, 8 KHz
> The way to use this is to make sure your signal (x) is :
> %# scale x to max 8 bit levels
> x=x/max(x)*128;
> %# resample x to the correct sampling freq.
> fs=44100
> playaudio(x(1:(fs/x):length(x)))
> 
> that should work I believe
> -- 
> Matt
> 
> For electronic musicians ...
> Vector Bass          : http://mffmvectorbass.sourceforge.net/
> For developers ...
> TimeScale Audio Mod  : http://mffmtimescale.sourceforge.net/
> Multimedia Time Code : http://mffmtimecode.sourceforge.net/
> 3D Audio Library     : http://mffm3daudiolib.sourceforge.net/
> 
> 
> 
> -------------------------------------------------------------
> Octave is freely available under the terms of the GNU GPL.
> 
> Octave's home on the web:  http://www.octave.org
> How to fund new projects:  http://www.octave.org/funding.html
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Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
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