[PD] physical modelling/general pd

[Jack]

Le 8 août 08 à 14:46, Julian Brooks a écrit :

> Hi Jack,
>
> Well I was surprised that someone else hadn't tried it already, to be
> honest.
>
> Congratulations, respect, and thanks for showing me that it is indeed
> possible.
>
> If you don't mind I would like to be able to email you with  
> problems that I
> think you can help/give advise for.
I think the better way is to post on the Pd list because i'm not  
always available to answer (lot of work sometimes) and a lot of  
people are good users of this programming language. The list exists  
for this sort of problem ;)
You have a lot of time to realize your patch, i think after 12 months  
you will have a good patch for your wind chime. All you need is to  
know PD/GEM/PMPD. I will be happy to help you and to answer to you on  
the list like a lot of other people.
++

Jack


>
> Best wishes,
>
> Jb
>
> -----Original Message-----
> From: pd-list-bounces at iem.at [mailto:pd-list-bounces at iem.at] On  
> Behalf Of
> Jack
> Sent: 08 August 2008 12:38
> To: cyrille henry
> Cc: pd-list at iem.at; Mark Sexton
> Subject: Re: [PD] physical modelling/general pd
>
> Hello Julian,
> I have done a wind chime there is 2-3 years ago with PD/GEM/PMPD. I
> used PHP to get on the web the value of direction and force of wind
> in differents cities in Europe.
> Here a link for a video without sound (i remove it from the export) :
> http://djrayban2.free.fr/Movie/windChime.mov
> ++
>
> Jack
>
> Le 8 août 08 à 12:16, cyrille henry a écrit :
>
>> 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" <julian.brooks at virgin.net>
>>>> Subject: [PD] physical modelling/general pd - mentor/tuition sought
>>>> (money offered)
>>>> To: <pd-list at iem.at>
>>>> Message-ID: <000001c8f881$0d514a40$27f3dec0$@brooks at 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
>>>>
>>>
>>>
>>>
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