What do you mean by break, crashes? If yes, what version of libpd are you using? Up until about a month ago, floating point exceptions (such as NAN) would crash libpd, whereas pd-vanilla ignores them. Peter B. recently added a commit that changed this:
https://github.com/libpd/libpd/commit/27c848a56d3d27e62231f8b0d9ef17c7c56cd9f9 Anywho, you'll probably want to take care of those NAN's anyway. :) Not sure why pd vanilla ignores SIGFPE. cheers, Rich On Tue, Mar 20, 2012 at 4:57 PM, Ed Kelly <[email protected]> wrote: > Hi, > > I'm trying to design or find a resonant lowpass filter for use with libPd > for Openframeworks running on an iPhone 4. > > 1. I've tried the rjlib filter attached (filtertest_list.tar.gz) and it > works fine in Pd, but instantly breaks when I run it on the iPhone - all > other playing audio cuts out, and it is impossible to reset. I suspect that > the buffers fb1 fb2 ff1 ff2 ff3 are hitting NAN values and staying there, > but I haven't tested this. > > 2. I've had a go at implementing the filter from > http://www.musicdsp.org/archive.php?classid=3#25 as a Pd external > (mvcf~.tar.gz) and it is very efficient CPU-wise. However, higher values of > f or q cause the internal filter buffers to hit NAN and stay there (tested > in Pd - I haven't tried this on the iPhone yet). > > I would ideally like to find out why the second attempt breaks at high q > and/or f, as what I want is a 24dB/Octave moog-ish filter. I'm sure those > of you with higher math skills will intuitively know why, but I'm just > learning calculus now (my early education was a bit chaotic). I'm also > limited by the fact that this is for a commercial project (although I'll be > happy to share the code :) so I can't just take a GPL external and > recompiled libpd with it. > > Ed > > Gemnotes-0.1alpha: Live music notation for Pure Data > http://sharktracks.co.uk/ > > _______________________________________________ > Pd-dev mailing list > [email protected] > http://lists.puredata.info/listinfo/pd-dev > >
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