[PD] Relationship between constant-Q and FFT - can you do it in vanilla?

[Thomas Grill]

Hi,
apart from true CQ Gabor transformations there is a method for estimating the power spectra of arbitrary frequency scales. It's probably what you are looking for.
It is based on summing up power spectrum bins by use of triangular windows.
I made an implementation which is fairly general. It employs some dynamic patching to generate the individual filter bands.
spect_scaled.pd is the main abstraction, it comes with a demo file spect_scaled-help.pd

have fun, Thomas

--
Thomas Grill
http://grrrr.org

-------------- next part --------------
A non-text attachment was scrubbed...
Name: hz-log.pd
Type: application/octet-stream
Size: 131 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20170713/83f9fa13/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: list-map.pd
Type: application/octet-stream
Size: 1097 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20170713/83f9fa13/attachment-0001.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: log-hz.pd
Type: application/octet-stream
Size: 131 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20170713/83f9fa13/attachment-0002.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: scl2bin.pd
Type: application/octet-stream
Size: 1067 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20170713/83f9fa13/attachment-0003.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: spect_part.pd
Type: application/octet-stream
Size: 2306 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20170713/83f9fa13/attachment-0004.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: spect_parts.pd
Type: application/octet-stream
Size: 1586 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20170713/83f9fa13/attachment-0005.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: spect_scaled-help.pd
Type: application/octet-stream
Size: 621 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20170713/83f9fa13/attachment-0006.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: spect_scaled.pd
Type: application/octet-stream
Size: 774 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20170713/83f9fa13/attachment-0007.obj>
-------------- next part --------------




> Am 10.07.2017 um 22:01 schrieb Alexandre Torres Porres <porres at gmail.com>:
> 
> Howdy, trying to figure the relationship between constant-Q and FFT, and if you can make a constant-Q patch in vanilla based on [fft~]. This would be for an android app, so it'd be good if I didn't need an external.
> 
> I was checking the [constantq~] external, which is found here and in 'deken'. it's based on a paper by Puckette and Brown. I need help cause I can't read math or figure out code reasonably well, so I don't really know how it works. It seems it could be done just by rescaling the output of an FFT with logarithmic values, but I could be terribly wrong.
> 
> Thing is that I already have a pd patch with a logarithmic output here - this is not vanilla, but made on extended, but easily adaptable for vanilla (I'm also attaching it).
> 
> Also, how about just having a bank of filters with center frequencies around the tempered scale, could you have in practice the same thing as from [constantq~]?
> 
> thanks
> <6.Log_Freq.pd>_______________________________________________
> Pd-list at lists.iem.at mailing list
> UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 842 bytes
Desc: Message signed with OpenPGP using GPGMail
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20170713/83f9fa13/attachment.sig>