hello,
Mark Sexton a écrit : > Hi Julian > Building a physical model of a wind chime might be easier than you think, if > you use modal or banded waveguide approaches to physical modelling rather > than the brute force approach of pmpd. pmpd aim to model the movement, not the sound. the hamer and the tube of a simple wind chime could be modeled with about 10 masses. To create a physical model of the sound is very different. but you need both to model the wind chime. Cyrille > > If you think of the wind chimes should as stiff bars, banded waveguides > would be ideal and are much more computationally efficient to implement than > brute force approaches: a resonant filter and delay per mode you want to > synthesis. I'd recommend perhaps starting with a simple modal > implementation using filters and build up from there. This paper gives a > good introduction: > http://www.cs.ubc.ca/~kvdoel/publications/modalpaper.pdf > > > If you're not familiar with modal synthesis and banded waveguides there's > plenty of information online and Perry Cook's book gives a good overview of > a range of approaches to modelling. > http://www.cs.princeton.edu/~prc/AKPetersBook.htm > > Some starting hints if you want to go down this route: > > 1. Create an impulse: a buffer of noise or single sample impulse > 2. Feed this into perhaps 5 band pass IIR filters with a very narrow Q, > these will provide your resonant modes for each chime. > 3. The frequencies of these filters will probably be non-integer multiples > of the fundamental, eventually you can get these by analysing an actual wind > chime, but if you wanted to build a proof of concept now then these are > typical modes of an aluminium bar (you can find further modal frequency > ratios in the Csound manual): > [1, 2.756, 5.423, 8.988, 13.448, 18.680] > 4. Scale the outputs of each of the resonant filters as appropriate, this > should be straight forward once you've done an audio analysis of your wind > chime. > > At this point you have a simple resonating model of a wind chime. > > 5. Perhaps replace the impulse: you can remove the resonant components of > your wind chime recording and this will leave you with the original noise > impulse. Using this to trigger your model should help improve realism. > 6. Create a banded waveguide version, by adding feedback delays for each > mode. (have a read of this paper and a look at Fig. 4): > http://soundlab.cs.princeton.edu/publications/1999_icmc_bar.pdf > > There's a few further tweaks and improvements that can be done, but > something along these lines should give a good result, be fairly easy to > implement and run more efficiently than brute force. > > Happy to chat more on or off list on the physical model side or algorithmic > composition side, but you may find it easier than you thought once you get > going. > > > All the best > > Mark Sexton > Senior Lecturer > MSc Computational Sound > University of Portsmouth > >> Message: 2 >> Date: Thu, 7 Aug 2008 12:30:51 +0100 >> From: "Julian Brooks" <[EMAIL PROTECTED]> >> Subject: [PD] physical modelling/general pd - mentor/tuition sought >> (money offered) >> To: <pd-list@iem.at> >> Message-ID: <[EMAIL PROTECTED]@virgin.net> >> Content-Type: text/plain; charset="us-ascii" >> >> Hi all, >> >> >> >> I have a 12 month project as part of a masters degree, where I wish to build >> a physical model of a wind chime. I then want to use the interface to play >> some of my indeterminate compositions. I was going to attempt it for my >> undergraduate degree but realised that it was far too complex for the >> available time that I had then. >> >> >> >> I have been using pd for a few years now, list lurking, working through >> basic examples, building simple tools, using other peoples patches etc. But >> this is too complex for me to do on my own. At my uni there isn't anyone >> with better skills than me and I don't know of any local fellow patchers. >> >> >> >> Now as a musician, when I need to up my skills, I will look to find some >> lessons when I have got as far as I can on my own. >> >> >> >> So here goes... >> >> >> >> Is there anyone with an hour a week to spare who can offer some >> mentoring/tuition for what we can deem to be the 'going rate'. I am more >> than happy to do this remotely/online, I'm sure there is a way we can work >> it out. There would be full credit given of course. >> >> >> >> Pmpd seems like the way to go with this. I have worked through the >> examples, and, although I have my eye on what examples I would presume to be >> the best starting points, I'm struggling to get started. The physical >> modelling is where I first need to start but there's loads of pd stuff I >> would like to be able to work through with someone, so this could be a (me >> love you)longtime regular small money earner, if anyone's interested. >> >> >> >> I am in Hebden Bridge, West Yorkshire, UK, by the way. Any pd'ers local, >> give us a shout. >> >> >> >> Best wishes to all, >> >> >> >> Jb >> > > > > _______________________________________________ > Pd-list@iem.at mailing list > UNSUBSCRIBE and account-management -> > http://lists.puredata.info/listinfo/pd-list > > _______________________________________________ Pd-list@iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list