Subject: Re: [linux-audio-user] changing speed without changing pitch
From: jjbenham_AT_chicagoguitar.com
Date: Wed Aug 21 2002 - 01:26:55 EEST
Have you ever considered doing a csound vocoder analysis of the file you
want to stretch. This is the cleanest sounding time stretch I have ever
heard. Try it! It takes more effort and cpu power than using snd but the
results will amaze.
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
then the sco file.
i1 0 1200
e
This should make the sound sample last 20 minutes no matter how long the
original file length was. It also will not change the pitch.
To perform a vocoder analysis on a file do:
csound -U pvanal -n 1024 -w 4 file.wav analysis.pvc
You can look up in csounds reference if you want to know how to control each
variable. It is much more dificult like I said but it is the best sound. I
took a sound that was only 30 seconds long and stretched to 20 min and it
did not sound extremely granulated.
Jeremiah
On Tue, Aug 20, 2002 at 02:56:01PM -0700, Peter Jay Salzman wrote:
> cool, thank you. i managed to find "expander". the results are
> ok. certainly good enough to pick out passages with.
>
> the docs mention that this works better with some files than others.
> i'd like to ask an obnoxious question -- is this as good as it gets?
>
> do all speed changers make music sound chorusey? is there anything a
> competant C programmer (who has no sound experience) can do to help
> raise the quality of this program?
>
>
> also, i'm interested in going back to a certain point in the music
> repeatedly until i get things right. the docs mention that snd is
> loosely based on emacs. is there something akin to vim's "markers"?
> some way i can set a beginning and end of a portion of the wav file and
> either have snd loop between those two points or perhaps just jump back
> to the beginning of the start of the portion?
>
> if so, can you point me to a keyword i can look up in the docs?
>
> lastly, does your book go into using snd? the docs are pretty damned
> extensive. it would be nice to read something that takes me through the
> high points before getting into the nitty gritty.
>
> thanks!
> pete
>
> ps- in real life i'm a physicist who has entirely too much fun
> administrating and programming on my own linux systems (i currently
> don't and never have owned any microsoft products, so i don't know
> what's out there for other OS's).
>
> my girlfriend also uses linux, but is completely uninterested in
> anything other than using the computer to be productive. just last
> night i kind of got peeved at her because i had to tell her how to tar
> up a directory and save it as a tar.bz2 file. for like the millionth
> time. she simply has very little interest in knowing how to use linux.
> she just wants to be productive with her computer.
>
> after playing around with sox and snd, i think i'm beginning to
> understand her better. :)
>
>
> begin Dave Phillips <dlphilp_AT_bright.net>
> > Peter Jay Salzman wrote:
> >
> > > it would be easier for me to pick out guitar parts if i were able to
> > > slow down the speed of a wav/mp3 file without changing the pitch.
> > >
> > > supposedly, sox can do it. but darned if i can figure that program out.
> > > i'm not shy about command line interfaces, but that program needs a
> > > wrapper!
> > >
> > > i assume what i can do is possible. as i understand it, it's easy to
> > > change the speed of digital music without changing the pitch.
> > >
> > > can someone tell me how to accomplish this?
> >
> > Hi, Pete:
> >
> > I do it with Snd. I've been using it to transcribe things like Charlie
> > Christian guitar solos and a harmonica solo by Sugar Blue. Works great !
> >
> > Best regards,
> >
> > == Dave Phillips
> >
> > The Book Of Linux Music & Sound at http://www.nostarch.com/lms.htm
> > The Linux Soundapps Site at http://linux-sound.org
>
> --
> GPG Fingerprint: B9F1 6CF3 47C4 7CD8 D33E 70A9 A3B9 1945 67EA 951D
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