Akai S5000 Operator's Manual download pdf (Page 173)

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TIMESTRETCH

Timestretch allows you to alter the length of a sample, shortening it or lengthening it, without

changing its pitch. Before we look at how to operate the timestretch functions on the S6000, let us

first look briefly at how timestretch works.

Timestretch works by instructing the digital signal processor to analyse the signal and insert or

delete blocks of sample data at appropriate places and crossfades are used to make the insertions

and deletions as seamless as possible. This has the effect of lengthening or shortening a recording.

As you can see from the following diagram, blocks of sample data have been inserted to create a

200% timestretch. The overall envelope of the sound data is preserved but there is twice as much

data in it causing it to play back twice as slow.

SAMPLE DATA BLOCKS

ORIGINAL RECORDING

WITH 200% TIMESTRETCH

In the following diagram, data has been removed to make the recording play back faster.

ORIGINAL RECORDING

70% TIMESTRETCH

Unfortunately, however, perfect results using timestretch are sometimes difficult to achieve. It is

not a limitation of software or hardware but due to the fact that, although the processor is clever, it

is not

that

clever and can sometimes make mistakes in deciding which sample to insert or remove.

The end result of this is that, on occasions, especially with stretch factors exceeding 10% or so,

you may get an echo or ‘flam’ effect on some transients because the processor has inserted a

transient. When shrinking a recording, you may find a transient softened because the processor

has decided to remove it. You will find this to be the case more or less on all devices that feature

some form of time compression or expansion.

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Akai S5000 Operator's Manual Page 173