# Re: [music-dsp] Reading a buffer at variable speed

```>> The buffer must be read at a variable speed,

Do you mean it has to be played out at higher sample rates ?```
```
>> how long will it take to play the whole buffer

If you can derive an average rate out of it then you can determine it.

-ben

________________________________
From: music-dsp-boun...@music.columbia.edu
<music-dsp-boun...@music.columbia.edu> on behalf of Maximiliano Estudies
<maxiestud...@gmail.com>
Sent: Tuesday, February 6, 2018 8:15 PM
To: music-dsp@music.columbia.edu
Subject: [music-dsp] Reading a buffer at variable speed

I am having trouble with this concept for quite some time now, I hope that I
can explain it well enough so you can understand what I mean.
I have signal stored in a buffer of known length. The buffer must be read at a
variable speed, and the variations in speed have to be exponential, so that the
resulting glissandi are (aurally) linear. In order to do that I came up with
the following formula:

x[t] = t * sample_rate * end_speed^(x[t] / T)     where T is the total length
of the buffer in samples.

This doesn’t seem to work and I can’t understand why.

And my second question is, how can I get the resulting length in milliseconds?
(how long will it take to play the whole buffer)

I hope I managed to be clear enough!

Maxi

--
Maximiliano Estudies
+49 176 36784771
maxiestudies.com<http://maxiestudies.com>
```
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