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Re: Pitch-Shift on the iPhone
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Re: Pitch-Shift on the iPhone


  • Subject: Re: Pitch-Shift on the iPhone
  • From: Richard Dobson <email@hidden>
  • Date: Fri, 06 Mar 2009 11:54:55 +0000

tahome izwah wrote:
Hi Hamish, I think there is some confusion of terms in our discussion
- let me clarify:

You said: "You can change the pitch of something by timestretching it"

..which is wrong - time stretching changes the speed, not the pitch.
Which is why I replied saying:

"you change the pitch by pitch shifting"

That's all I wanted to point out in the context of your last email.

Time stretch + sample rate conversion = pitch shift
Pitch shift + sample rate conversion = time stretch

I think we all agree on this.

There is one fundamental distinction however: you can pitch-scale a live stream directly (using say the dspdimension code), but timescaling ostensibly has to be an offline (file-based) process. Offline processes often do pitch shift by timescaling and then resampling; that method cannot naturally be applied to the real-time streaming context, where a sound by definition is potentially infinite in duration. So, much depends on whether the OP wants to apply pitch shift in real time or only to a pre-recorded file.


Richard Dobson

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  • Follow-Ups:
    • Re: Pitch-Shift on the iPhone
      • From: Hamish Allan <email@hidden>
References: 
 >Pitch-Shift on the iPhone (From: email@hidden)
 >RE: Pitch-Shift on the iPhone (From: "Andrew E. Davidson" <email@hidden>)
 >Re: Pitch-Shift on the iPhone (From: tahome izwah <email@hidden>)
 >Re: Pitch-Shift on the iPhone (From: Hamish Allan <email@hidden>)
 >Re: Pitch-Shift on the iPhone (From: tahome izwah <email@hidden>)
 >Re: Pitch-Shift on the iPhone (From: Hamish Allan <email@hidden>)
 >Re: Pitch-Shift on the iPhone (From: tahome izwah <email@hidden>)

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