Re: Pitch-Shift on the iPhone
Re: Pitch-Shift on the iPhone
- Subject: Re: Pitch-Shift on the iPhone
- From: William Stewart <email@hidden>
- Date: Fri, 6 Mar 2009 10:51:42 -0800
you don't actually need access to all of the samples, its just that
for a given output, you require a variable number of samples to
produce that output.
So, the output side of a time-pitch operation can be real-time, but
its input data cannot be.
You can see this in AULab.... If you add a generator audio unit to the
graph, you can insert a time pitch (or any converter unit that
publishes a UI) in that channel strip, because a generator unit is
potentially able to respond to non-real-time generation (for instance,
using the file player, or a tone generator as two examples, where they
can just produce the requested output, regardless of how variable this
it over time)
Bill
On Mar 6, 2009, at 4:53 AM, Hamish Allan wrote:
On Fri, Mar 6, 2009 at 12:26 PM, Richard Dobson
<email@hidden> wrote:
Well, if you are slowing down, you pile up incoming audio, possibly
infinitely (speed 0.5: 5 secs in --> 2.5 secs out), or conversely
you run
out of input if you try to speed up (audio hasn't arrived yet).
True!
Or did you
have some other mechanism in mind? Short one-shot sounds? That
would be a
rapid-turnover but technically offline process.
I understood "offline" to mean that you needed to have access to the
whole input before you could start processing -- the canonical example
being the distinction between insertion sort (online) and selection
sort (offline). But you're quite right that the advantage of real-time
processing is pretty much moot because of the conceptual issue you
describe above.
Hamish
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