[linux-audio-user] Digital audio files for hardware verification

[Paul Winkler]

This is a huge can of worms you're opening here ...
A simple sawtooth wave is going to have a lot of aliasing, unless you
specifically use an algorithm that produces a band-limited approximation,
at which point you've already left me far behind ;-)

For FFT, my needs have been very modest, I just eyeball stuff in Snd.
There is also www.baudline.com , very slick but it is merely free and not Free.

-PW

On 10/25/05, Mark Knecht <markknecht at gmail.com> wrote:
> On 10/25/05, Paul Winkler <pw_lists at slinkp.com> wrote:
> > Awk is powerful and concise, but it's not my friend - I can never remember how
> > the heck it works ;-)
> >
> > I'd probably do like Paul D. suggests and use existing tools - e.g.
> > find something
> > to generate an appropriate soundfile, then feed it through sox.
> > But just for fun, here's something silly I just whipped up:
> >
> > $ ./sine_hex.py
> > Usage: ./sine_hex.py frequency [sampling rate] [bits]
> > Print one cycle of a sine wave of approximately the
> > given frequency.
> > Values given in hex with *bits* precision at *sampling rate*.
> > Default sampling rate is 44100. Default bits is 16.
> >
> > pwinkler at Winkler-P-LT2K ~
> > $ ./sine_hex.py 24000 48000
> > 0000
> > ffff
> >
> > pwinkler at Winkler-P-LT2K ~
> > $ ./sine_hex.py 3000 48000
> > 0000
> > 31f1
> > 61f7
> > 8e39
> > b504
> > d4da
> > ec82
> > fb14
> > ffff
> > fb14
> > ec82
> > d4da
> > b504
> > 8e39
> > 61f7
> > 31f1
> >
> > And here's the source. Most of it is argument handling :-)
> > http://www.slinkp.com/~paul/sine_hex.py
> >
>
> Intereing. Another country heard from.
>
> One question that comes to mind, as I play with these solutions, is
> deciding how to evaluate the outputs. For instance I was fiddling with
> generating a sawtooth from Marcus' s method. I could do the same with
> this, but how do I know each of them is really implementing what I'm
> interested in?
>
> What tools do people use for FFT analysis on files like this?
>
> Cheers,
> Mark
>
>


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