Subject: RE: [linux-audio-user] changing speed without changing pitch
From: Stuart Allie (allies_AT_hydstra.com)
Date: Tue Oct 22 2002 - 01:33:48 EEST
Hi,
I *finally* got around to trying the csound method of changing the speed of
an audio file without changing the pitch, but it didn't work for me :(
I used the following "orc" file:
> sr = 44100
> kr = 4410
> ksmps = 10
> nchnls = 1
>
> instr 1
> kfreqscale = 1
> ispecwp = 0
> ktime line 1, p3, 0
> apvl pvoc ktime, kfreqscale, "file.pvc", ispecwp
> out apvl
> endin
and then the "sco" file:
> i1 0 12
> e
with a 6 second sample, so this should double the audio to 12 seconds. I did
the PV analysis like this:
> csound -U pvanal -n 1024 -w 4 file.wav file.pvc
and then ran csound via:
> csound -W -R -d file.orc file.sco -o slow.wav
and then I waited for a little while :)
When csound was done, the ourput file was, well, interesting...
Basically the input file was 6 seconds of single-note guitar playing, and
the output was a weird (though not unpleasant :) whooshing-sweeping-phasing
sound for 2 seconds, then a faint LFO-type sound to the end of the file. No
sign of the original clip, slowed or otherwise.
Can anybody out there tell me what I (or csound :) did wrong?
Thanks in advance,
Stuart
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