What is "Expander"?
Expander is a small program which can stretch a WAV file in time without changing its pitch. For example, a piece slowed down by a factor of two:

Which operating system is it written for?
It works under Microsoft Windows 95/98/2000.

Does it have some special hardware requirement?
No. Although a fast computer is recommended because the computation is very time-consuming. Below you can see the CPU usage increase as the computer stretches the WAV file, and then decrease as it finishes:

How much is it?
It is shareware. The original version, 1.x was freeware, but it could do only integer-factor expansions. This new version, 2.x can do now arbitrary expansions and compressions, but the freely downloadable version is limited to process at most 8 seconds of input. Of course, there is no such limitation for integer-rate expansion, that version 1.x could already do.

How does it work?
It uses the Fast Fourier Transform to analyze, modify and synthesize the signal. More scientifically you may call it a short-time Fourier transform analyzer-synthetizer or a phase vocoder.

Are there any examples?
Yes, have a look on the Examples page for examples you can listen to, and screen shots of the program.

OK, I want to download it.
The program is available on the Download page

What if I want the fully functional version?
The price is $20 or something of equivalent value (e.g. an audio CD). Contact me via E-Mail for details.

Who wrote the program?
Me - Laszlo Toth. E-Mail Me.