Lib fftw

hi guys,

just saw today that there is a libfftw3-3.dll in the vvvv bin folder – I hope you guys know that the libfftw is under the GNU GPL … which as I my understanding is, means that the rest must also be under a GNU GPL licence.

… definitiv one of the best fft libs arround … but with a very restrictive licence. there was a discussion about that in the openframeworks forum about that!


as we just use the compiled dll thats ok as far as i know. we do not use any code, but just dynamically link the dll.

helo m9,

thanks for that hint. libfftw3-3.dll is used by BeatTracker (DShow9) (included since beta14) which is available as opensource but still i’d say you’re right that we are not allowed to distribute it with vvvv. i’ll check that with the license owners.

if you trust wikipedia, linking libraries is an unclear issue:

another question is, if you distribute the library, do you also have to distribute (or make available on request) its source?

edit: read the OF-thread, apparently there are alternatives if needed: the KISS fft library (BSD licence).

right, it might be unclear, but the fftw authors seem to expect you to use GPL if you use fftw, i would say their opinion counts:

Non-free versions of FFTW are available under terms different than the General Public License. (e.g. they do not require you to accompany any object code using FFTW with the corresponding source code.)

found here:

yeah, kiss fft would be a alternative but it’s not so fast as fftw (wich I think is the fastest free available one).

yeah guys - sorry for that ;)


thanks again for the hint m9,

got in contact with the authors of fftw and it is ok for them if we just stop distributing their library from now on. what we already did. the current download does no longer include their .dll. we should have definitely taken better care of what goes into our release in the first place…

now of course the beattracker is in a non-functional state and therefore i contacted meanimal (its author) who mentioned that some work on the beattracker was imminent anyway…so lets see what he comes up with.

i just got a question , what if somebody make a contribution on just this node ?
(i really don t know , i havnt made a node yet)

it wouldn t be distributed in vvvv but everybody could still use it , could anybody confirm that it is right to do it , or would it be against the licence ?

what about the BeatDetector (bass) node ? i dont really get what is an Handle pin , except that you can only plug it to a filestream node , or can we plug it to a live audio channel , like tricking it with some DynamicStream (bass) node?

(i still didn t figured out how to use it)

ps : i was quite found of the phase , do you have any advice how to replace it ?

Shouldn’t it be possible to include the BeatTracker in a non-functional state with a link to download libfftw3-3.dll separately to make it work ? Similar to programs that use lame_enc.dll from mp3 export functions.

nope. vvvv must not link to GPL code which it would still do if we only ommit the .dll.

concerning the bass nodes: they should be the way to go eccept you need an extra bass-license to use those in a commercial setup. the _ Handle_ is simply where you connect the handle-output of any of the other bass nodes. DShow9 audio nodes and Bass audio nodes cannot be mixed.

Are you sure about that? Its not vvvv that links to the .dll but the (open source) BeatTracker that does, no?

heh, yes, but vvvv statically has to link to directshow filters used (of which the BeatTracker is one).

Ah, I see. :(