[PD] Pre Loading a Delay Line

[derek holzer]

Hi Michael,

technically, reading from a table and changing the playback speed isn't 
really KS. That's more like wavetable synthesis with en envelope. I 
always thought KS was dependent on attenuated feedback. But if it works 
do it!

I don't have a handy example of tabread/tabwrite as a delay, 
unfortunately. Frank Barknecht has a [pluck~] abstraction in CVS:

"/abstractions/footils/foo/pluck~.pd"

But I'm sure it uses [vd~]. Might be interesting to have a look at. And 
this abstraction from Orm Finnendahl adapted by João Miguel Pais:

http://lists.puredata.info/pipermail/pd-list/attachments/20060412/75593d59/ks.obj

(textfile...save as "ks.pd")

Another idea, why not preload the delay line in realtime by triggering a 
sample when you need the note? That seems much more like "textbook" KS, 
which is usually triggered by a burst of noise (though I prefer a  mic 
input).

best,
d.

Michael Garrett wrote:
> Thanks or the feedback!! I have a good KS synthesizer patched up
> That gives me good results, with the block size for the waveguide set
> At blocksize one as you suggested.
> 
> The table is a good idea, instead of time dialating the excitation waveform
> or changing the delay time to get different pitches, I can just read / write
> the table (delay line) at different rates (in modeling terms, changing the
> speed of sound). Easier, and only requires a constant length table copy for
> each note.
> 
> I have been peaking into the source with the intent of creating an external
> which performs the same function as the current delay object (with vd~) but
> has an input to preload the delay line from a table.
> 
> Is there an example that you know of that uses tabread and write as a delay
> line??
> 
> Thanks!!
> 
> Michael
> 
> -----Original Message-----
> From: derek holzer [mailto:derek at x-i.net] 
> Sent: Wednesday, November 29, 2006 8:01 PM
> To: Michael Garrett
> Cc: pd-list at iem.at
> Subject: Re: [PD] Pre Loading a Delay Line
> 
> Hi Michael,
> 
> Michael Garrett wrote:
>> I need to pre fill a delay line, in a Karplus Strong oscillator. That 
>> data will then be overwritten during the duration
>>
>> Of the 'note'. Is there a 'built in mechanism for accomplishing this, or 
>> do I need to construct something using a table.
>>
>> I need the delay line to be interpolating. I am setting the delay based 
>> on the incoming note, and ideally would fill the
>> line with the same waveform, time dilated to fit the required length.
> 
> Short answer: no, there is no way to "pre fill" the delay that is native 
> to the [delwrite~] object.
> 
> You're on the right track to use a table, however. You could also go a 
> step further and build your own delay line using two tables, which 
> transfer back and forth to each other with [tabwrite~], and could be 
> preloaded with whatever you need. The [tabread4~] object should read 
> your tables with enough interpolation for Karplus Strong synthesis. 
> Otherwise, [delwrite~] and [vd~] are normally used for this, and [vd~ ] 
> seems to interpolate well enough. You'll have to set a very low 
> blocksize with the [block~] object to synthesize high frequencies in any 
> case.
> 
> In the past, there's been quite a bit of discussion about KS synthesis 
> on the list. And it sounds like you have a rather complicated approach 
> to it (or at least more so than standard KS synthesis). If you're 
> interested, it might be worth checking some of these threads for more tips.
> 
> best,
> d.
> 
> 


-- 
derek holzer ::: http://www.umatic.nl
---Oblique Strategy # 109:
"Lost in useless territory"