[PD] Play/loop and pitch change

e skogen eskogen at usfamily.net
Fri Aug 8 15:37:08 CEST 2003

this point has been confusing to me, as well. and, like pix, i've been 
avoiding it because i am lazy :P

what if:

1. the phasor~ is going from 0 to 1
2. the phasor~ is multiplied by ((the array size) - 1)
3. this value is added to by one


|  [arraysize]
|  |
|  [- 1]
|  |
[+~ 1]

wouldn't this give you your read from 1 to size-2? or is my math wrong?
or do you really need to provide wrap-around points (guard points) for 
cleanly looping samples?

i'm going to have to look at the docs more when i get the chance.

also, Soeren: if it's small, could you send me a copy of the soundfile 
that's causing clicks?


pix wrote:
> more than likely it's your sample data.
> try a sample that is completely silent. if the click goes away, it is
> likely your data.
> also, try filling your array using the "sinesum" message from
> 2.control.examples/15.arrays.pd if this doesn't click, it is definitely
> your data.
> note on the tabread4~ help page that tabread4~ requires guard points
> (although it doesn't say that explicitly). valid reads are from 1 to
> size-2. you are reading from 0 to (size-1) if you are just multiplying a
> phasor.
> not thinking too hard about it (eg, i could easily be wrong), i think the
> guard points situation is that the sample at 0 should be a copy of the
> sample at size-2 and the sample at size-1 should be a copy of the sample
> at 1.
> i guess to build a table like this from a normal non-guard-pointed sample,
> you could grow (suing a resize message) the given table by 2 samples, then
> set the sample at newsize-2 to the sample at 0, and the sample at
> newsize-1 to the sample at 1.
> now if you index the table using (phasor*newsize-2)+1 you should get a
> clean loop, but unfortunately the sample will be offset by one sample. you
> could wither fix this in the indexing ( something like
> ((phasor*newsize-2)-1 mod (newsize-2))+1 ) or copy all of the samples over
> by one when you are fixing the table.
> making some things to do this guard point generation and indexing would be
> a nice pair of abstractions to make available.
> okay.. i think i just thought about that way too much.
> you will be able to explain any huge errors in my reasoning, by knowing
> that i didn't test any of this. i've never noticed clicking when just
> using tabread4~ without doing all of this jiggery-pokery, as my samples
> are normally kind of noisy... but i always new i was being lazy.
> by the way, instead of using a modified phasor~ to do one-shot, you could
> send a line~ object a "0, 1 <period>" message.
> pix.
> On Fri, 08 Aug 2003 10:05:17 +0200
> Søren Bovbjerg <sb at cvmt.dk> wrote:
>>I am searching for a PD object (external/native) that can play samples 
>>from an array in both loop and "single shot" mode while being able to 
>>change playback speed.
>>So far I have been using a phasor~ (modified to create 1 or unlimited 
>>ramps) + tabread4~ but I am experiencing a very small click when the 
>>sound loops. The click is only noticable when the sample is a pure 
>>looping tone. The problem exists with both wav and aiff files so I don't
>>thing it is a "header" problem.
>>I have attached the sampler (without modified phasor~) I have been using
>>so far. It should run on any newer PD version.
>>Any ideas are welcome.

(ascii pseudo-patch)!!! yazaaahhh!!

------ http://USFamily.Net/info - Unlimited Internet - From $8.99/mo! ------

More information about the Pd-list mailing list