[comp.sys.ibm.pc.misc] Changing Frequency of Sampled Sound

fasciano@IRO.UMontreal.CA (Massimo Fasciano) (10/23/90)

Hi everybody,

 Does anybody know a way (source code or a good explanation)
 to change a sampled sound's frequency (pitch) without changing
 the sampling rate or the length of the sound.

 Ex: I have sampled a piano note at 11KHz and it lasts 0.4 seconds.
     I want to be able to generate other notes (frequencies) from this
     one without having to sample every one of them on the piano. The
     resulting notes must all be of the same duration (0.4 sec) 
     and sampling rate (11KHz).

This problem is simple if you can transform the waveform into an equation
(sine wave) because you can change the freq by manipulating constants in
the equation but i don't see how it can be done (i know it can be done since
some sampling synths do it) with complex (real life) waveforms.


			Thanks in advance

--

Massimo Fasciano (fasciano@iro.umontreal.ca)