Re: [music-dsp] WSOLA on RealTime

[Jacob Penn]

Ahh yeah I gotcha,

Yes, in the case of slow down, there Is a finite amount you’re able to slow
down based on the size of the circular buffer of input data in use.

In my personal applications I offer users the ability to restart the
stretch from the writehead at a musical value. Conveniently the slowest
rate for this control will stop the overflow ; )

Can sound quite nice!

Best,

[image: insignia] 
JACOB PENN.MUMUKSHU 
612.388.5992

On September 26, 2018 at 2:21:29 PM, robert bristow-johnson (
r...@audioimagination.com) wrote:



 Original Message 
Subject: Re: [music-dsp] WSOLA on RealTime
From: "Jacob Penn" 
Date: Wed, September 26, 2018 5:00 pm
To: r...@audioimagination.com
music-dsp@music.columbia.edu
--

> You can indeed do it on real time audio but the tricks is like the
previous
> email, you’ll need to devise strategies for pitching things up, as you’ll
> be lacking the necessary information to move faster across the buffer from
> the write head position.
>
> You’ll also obviously only be able to slow down a signal, and not speed it
> up.

no, even if you slow it down, any finite-sized buffer will eventually
overflow.  i presume you mean time-scaling (not pitch shifting) using WSOLA.

by "real-time", i mean live samples going in and (assuming no sample rate
conversion) the same number of samples going out in a given period of
time.  with an upper bound of delay (and the lower bound is imposed by
causality) and the process can run indefinitely.  so if you're slowing down
audio in real-time and you're running this process for a day.  or for a
year.


--

r b-j r...@audioimagination.com

"Imagination is more important than knowledge."







___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] WSOLA on RealTime

[robert bristow-johnson]

 Original Message 

Subject: Re: [music-dsp] WSOLA on RealTime

From: "Jacob Penn" 

Date: Wed, September 26, 2018 5:00 pm

To: r...@audioimagination.com

music-dsp@music.columbia.edu

--



> You can indeed do it on real time audio but the tricks is like the previous

> email, youll need to devise strategies for pitching things up, as 
> youll

> be lacking the necessary information to move faster across the buffer from

> the write head position.

>

> Youll also obviously only be able to slow down a signal, and not speed 
> it

> up.
no, even if you slow it down, any finite-sized buffer will eventually 
overflow.� i presume you mean time-scaling (not pitch shifting) using WSOLA.
by "real-time", i mean live samples going in and (assuming no sample rate 
conversion) the same number of samples
going out in a given period of time.� with an upper bound of delay (and the 
lower bound is imposed by causality) and the process can run indefinitely.� so 
if you're slowing down audio in real-time and you're running this process for a 
day.� or for a year.

--



r b-j� � � � � � � � � � � � �r...@audioimagination.com



"Imagination is more important than knowledge."

�
�
�
�
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] WSOLA on RealTime

[Jacob Penn]

You can indeed do it on real time audio but the tricks is like the previous
email, you’ll need to devise strategies for pitching things up, as you’ll
be lacking the necessary information to move faster across the buffer from
the write head position.

You’ll also obviously only be able to slow down a signal, and not speed it
up.

Best,

[image: insignia] 
JACOB PENN.MUMUKSHU 
612.388.5992

On September 26, 2018 at 1:50:37 PM, robert bristow-johnson (
r...@audioimagination.com) wrote:



WSOLA fundamentally does time-scaling.  time compression or time stretching
without changing pitch.  time-scaling is not normally thought of as
real-time because your input and output buffer pointers will collide.

combining time-scaling with resampling can make a pitch shifter (changes
pitch without changing speed or tempo) and that **can** and often is
real-time.  whatever stretching or compression the time-scaler does that
changes the length of the sound is undone by the resampling.  it's like if
you pitch it up an octave, the time-scaler (WSOLA or phase-vocoder or
whatever technique) makes your audio twice as long (and half as fast)
without changing pitch.  then you play that elongated audio back at twice
the speed which brings it back to the original tempo but the pitch is
bumped up an octave.

for playback of audio from a hard disk or some other mass storage, you can
use WSOLA or slow down or speed up the playback (without changing pitch)
but your playback device has to output more samples than normal if you're
speeding it up or fewer samples than normal to slow it down.  then, in
real-time, you can use the time scaler  make the more or fewer samples per
block to be the same as normal.

--

r b-j


 Original Message 
Subject: [music-dsp] WSOLA on RealTime
From: "Alex Dashevski" 
Date: Wed, September 26, 2018 3:25 pm
To: music-dsp@music.columbia.edu
--

> Can I implement WSOLA on realtime(audio buffer) ?
> I need to do resampling ? Right ?
>
> Thanks,
> Alex
> ___
> dupswapdrop: music-dsp mailing list
> music-dsp@music.columbia.edu
> https://lists.columbia.edu/mailman/listinfo/music-dsp








--

r b-j r...@audioimagination.com

"Imagination is more important than knowledge."







___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

[music-dsp] WSOLA on RealTime

[Alex Dashevski]

Can I implement WSOLA on realtime(audio buffer) ?
I need to do resampling ? Right ?

Thanks,
Alex
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp