On Mit, 2012-06-06 at 11:07 -0400, Matt Barber wrote: > > On Wed, 2012-06-06 at 09:53 +0200, Jeppi Jeppi wrote: > > > Hey, > > > I wonder whether there is something similar to Max' ipoke~ (an > > > interpolating buffer~ writer) for Pd. I should need it for some > > > physical modelling and resampling stuff. Otherwise, I could implement > > > it myself. It seems only interpolated reading is available (tabread4~ > > > and similar ones), not writing. > > > > This somehow reminds of the thread about settable [receive]. Is there > > really a need for the ability to do interpolated writing? Conceptually, > > is there any restriction if it is lacking? Can't everything that employs > > interpolated writing be achieved with interpolated reading as well? > > > > Maybe I'm not thinking hard enough... > > > > Roman > > > > If you're using it for modeling an acoustic space, for instance, an > interpolating write is the proper tool for stationary microphone and > moving sources. Interpolated read is more like a moving microphone. > > Imagine, for instance, how you would calculate the delay time of a > sound source moving toward a microphone, from the microphone's point > of view. Say it's 50ms away right now, and in a second it will be 40ms > away. The correct model of this is not to set an interpolated variable > delay read at 50ms right now, and ramp to 40ms over one second - that > would be looking 50ms into the past (of the source) right now and 40ms > into the past at 1 second from now, where what you need is to look > 50ms into the past of the source 50ms from now, and 40ms into the past > at 1040ms from now - so you'd need to delay the the signal controlling > the variable delay read itself by the appropriate amount, and that > signal would have to have the same information in it that you're > trying to generate with the read in the first place. > > This problem is easily solvable with a variable write (assuming for > the moment a stationary read) - with a variable write, it is as though > you're projecting samples into the read's future -- exactly what you > want. > > You can use the same logic for needing to use variable write into a > table rather than a delay line.
I see how it seems more logical/simple to model a moving source with a interpolating buffer writer. However, it's possible to model both cases, [moving source / stationary mic], [stationary source / moving mic] with a linear buffer writer and a interpolating buffer reader [1]. [1] http://en.wikipedia.org/wiki/Doppler_effect Roman _______________________________________________ Pd-list@iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list