Subject: Re: [linux-audio-dev] What I want, to stop using Windows
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Thu Sep 28 2000 - 13:00:47 EEST
On Wed, Sep 27, 2000 at 07:19:58PM +0300, Juhana Sadeharju wrote:
> >From: Steve Harris <S.W.Harris_AT_ecs.soton.ac.uk>
> >
> >2. An impluse convolver (is that the right term?) to replace Sonic Foundry's
> > Acoustic mirror, preferably file compatible.
>
> If you have its manual on-line, please mail it to me for looking at the
> thing. Or if you have time, please search info about the impulse response
> format. And I don't mean a file format, but something else: are the responses
> impulse responses to unit sample or to a square pulse.
The manual is a crappy windows help thing, but it doesn't say much
anyway. The actual impulses vary, but the recommended one is an impulse,
followed by a sine sweep followed by another impulse. You show the
software the WAV you used to record the impulse and it unravells it.
The are some impulses available for free from thier site at
http://www.sonicfoundry.com/download/ They are called sfi files usually,
but they are just wrappered WAV's, I think I can save the WAV files out
if that will help.
Acoustic mirror is dead cheap now, and there is a free limited demo
available from http://www.sonicfoundry.com/ so I recomend anyone with
windows and plenty of horsepower to try it (its a direct X plugin).
> I would like to know if the square pulse is the standard way to do impulses
> for Acoustic Mirror software. What would be the correct way to turn them
> to unit sample responses? Or is that needed at all?
My guess is that know what internal representation AM uses you could just
unravel that to an impulse/square wave. It may not be worth it though!
> I have tried music-dsp people to get interested in to design a DSP box
> which would be useful for multiple things:
> -standalone synth,
> -effect box,
> -mp3 player (with hard disk),
> -HiFi recorder (with hard disk),
> -MIDI controller
> -portable recorder (with batteries)
And run convolutions of course! A portable machine that could run DSP
algorithms and convolve from files stuck on compact flash cards or
whatever has been on my wish list for a long time.
In the studio I frequently use very large and complicated chains of
effects, and being able to just capture an impulse response of all the
static bits to use live would be great... which gets me thinking, I
wonder if you could apply dynamic impulses? A series of 16 (say) impulses
recoded with different settings and crossfade between them?
I presume thats how amp modelers like the Line 6 Pod work, but I don't
know.
- Steve
--
Stephen Harris
MALIBU Technical Officer & JoDI Webmaster
IAM Research Group
University of Southampton, UK
07970 557047
swh_AT_ecs.soton.ac.uk 023 8059 2774
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