PURE DATA forum~

Actually, I think I may have been a little hasty in my reply and realize that just saying making the speed constant doesn't make complete sense. The speed should remain constant. I think the problem is that the grain lengths get larger as the overall duration gets larger, and you have grain lengths associated with playback speed. This is where the windowing comes in handy. The grain size should correspond to the size of the envelope, not how long it takes to playback a certain segment of audio, as you have now. The playback part should be a constant speed, and the window should get longer or shorter. And they should overlap, too, so they crossfade in and out with each other.

Last edited by Maelstorm (2009-04-19 17:05:08)

Wow diplipito & maelstrom, very usefull stuff... thx for sharing this one.

Maelstrom, cool idea ,using phasor~ instead of metro.
now I m playng with phasor's phase.

One more thing (uncompleted, work in progress)

http://www.youtube.com/watch?v=0KO7Tsba8OU

I just have been looking at you timestretch patches. Look great and very useful, but I cannot get them to work as I seem to lack the edge~ object and the speedlimit object (both in Pd-0.42-5 and Pd-extended). I'm a PD beginner, so any help as where to get these, or bypass, or 'emulate' them would be greatly appreciated ... Thanks!
H

Thanks for the reply, Maelstorm. No, a cyclone library is not loaded. I searched for it, and found *inside* the Pd-extended Mac package a cyclone map, containing  files named edge~.pd_darwin and speedlim.pd_darwin. That is not a map that I can indicate as a startup path for, as it is *inside* Pd.
But I copied them to another map. Now the patch loads completely, and yes indeed, works! (In fact I also installed the latest version of Pd-ext: the read me *does* say that by default all these libraries should load; but apparently they don't ...)
Anyway.
Thanks a lot for the help. I want to implement timestretch as part of a sound-scene for the rjdj iPhone app, but for that I will need to bypass the edge~ and speedlim, as rjdj only gives acces to what is available in Pd-vanilla. Any hints as to how to do without would be greatly appreciated; and used with due credits of course :-)

best

__hars
http://harsmedia.com

[edge~] outputs a bang when a signal goes from zero to something out its left outlet and when it goes from something to zero out its right outlet. So by doing this:

[phasor~]
|
[expr~ $v1<.5]
|
[edge~]

you can detect when a [phasor~] has jumped from 1 to 0 at the end of it's phase. There is a downside, though, that didn't really occur to me when I made this patch: [edge~] only sends its bangs at the end of block boundaries, so it's not really sample accurate, which was what I was going for with the [phasor~].

With this patch you might be able to replace the [phasor~] approach with [metro] and [vline~]s. In fact, since those don't conform to block boundaries, it might technically be better.

Last edited by Maelstorm (2009-09-07 07:23:41)

@ookoi: take a look at this link to see if it fixes your start up preferences:

http://puredata.info/docs/faq/when-i-up … -libraries

One more grain sampler
I have added pitch shift control.

For doing time stretching/contraction I found examples B.12 and B.13 under the audio examples in the Help Browser of Pd very helpful. diplipito and maelstorm, your patches are pretty similar to what's going on in these examples.
Personally, I've just used a vline~ for the playback position which makes it easy to go forward or reverse. I suppose controlling it is a little messier though.

Good point. You should also look at the phase vocoding patches if you really want to do some awesome time stretching/contraction. It certainly won't give you a grain-y sound, which might be what you're interested in, but it's very smooth sounding.

They're kind of a lot more difficult to understand, but I definitely like the sound.

That's something I didn't handle in my patch, either. However, you could solve it like this:

(signal)
...                             [r $0-samples]
|                               |
[expr~ fmod($v1, $f2)]
|
[tabread4~ $0-file]

fmod() is a floating-point modulo, so it's like [wrap~] except it doesn't have to be constrained with 0-1.