Re: The doors of perception (was Re: Repeater latency)

[Kim Flint <kflint@loopers-delight.com>]

At 10:26 PM 7/23/2003, Nic Roozeboom wrote:
> >I assume the Repeater's audio delay is the same whether pitch-shifting 
>or
> >not.  Can anybody confirm this?
>
>(Sorry for the earlier empty premail)
>
>If it is, it is bound to be artificially made equal by design. The 
>minimum 
>delay (impulse response) for the pitch shift algorithm has to be much 
>longer than for unprocessed audio. Physics say that there is less and 
>less 
>'pitch' about a portion of sound the shorter you make the time interval 
>in 
>which you look.

there are a variety of ways to do pitch shifting algorithms in dsp, and 
they take varying amounts of buffering to implement. I'm only slightly 
familiar with this subject, so I'm not going to be able to explain the 
details. check the music-dsp list archives if this is interesting to you.

My only issue with the repeater in this case is that the direct through 
audio suffers this same buffering delay, and passes through a/d -> d/a 
conversion as well. I don't see the point of that. Direct through should 
just go direct through. Certainly in a world of musicians insisting their 
effects should be "true bypass", this is clearly going to annoy a lot of 
people. Personally, I think "true bypass" is kind of stupid. I don't mind 
if my signal passes through a few well designed opamps. Digital conversion 
can produce a lot of artifacts though, so I would rather not see my 
signals 
doing that when they don't have to. that's all. YMMV.

kim


______________________________________________________________________
Kim Flint                     | Looper's Delight
kflint@loopers-delight.com    | http://www.loopers-delight.com