waveform display playback speed

    Oct 22 2007 | 2:06 am
    Hi I was wonderin how to control the playback speed of a selected area (the highlighted selection) in the waveform display.
    This is something that is done easily in ableton live simply by raising the BPM.
    I know that by raising the sig~ in your groove~ object plays it back faster but it also raises the pitch. I would like to avoid pitch shifting.
    Thanks alot for your time and generosity.

    • Oct 22 2007 | 7:48 pm
      Use gizmo~ on the signal. It takes a little doing but is well worth it. To tie the speed change to the pitch (so that the pitch stays the same) you'd use the reciprocal of the speed (divide speed into 1. by using !/ 1. then send this pitch shift into gizmo~. So, twice the speed --> half the pitch, result = original pitch.) This works for a while, then starts to sound wacky (sometimes cool, sometimes not). Any program will have this degradation though. I like shifting way up, it sounds great to my wacked-out brain ;)
      Mess with the pfft~ settings inside gizmo~ to get what you want, some values are better for certain shifts. Small shifts to match tempo are generally fine.
    • Oct 22 2007 | 10:14 pm
      that 's a great idea !! why didn't I think of that!? I will try this out and give you some feedback. I'm still pretty new this software , but with guys like you , your making the learning curve less steep. thanks alot.
      Are there any other ways of doing this, is that the only way around the pitch shift?
      thanks again
    • Oct 23 2007 | 6:23 am
      Wow! Yeah, I'm working on my first live performance/improvisation patch, so this advice is great. I wasn't planning on worrying about the playback/pitch issues, but seeing as to how I've already played around with gizmo~, I'm going to give this a try. Here's a related question- I'm on a 2.16ghz C2D Macbook Pro (pretty powerful laptop) and am finding that using a handful of gizmo~/pfft~ objects (essentially just like what you find in the gizmo~ tutorial) is pretty taxing on the CPU. Not terribly bad, but when using 8 instances of the pfft~/gizmo~ pitch shifting patch, I'm up to 25-30% DSP status. This isn't that worrisome in and of itself, but this is without anything else going in the patch, and I intend to use the patch soundflower-ed to Logic. I'm assuming this has to do with the fact that Max/MSP doesn't take advantage of both of the cores in my laptop CPU. Is there some way to make multiple instances of the pfft~/gizmo~ pitch shifting patch more efficient? Perhaps utilize that second core somehow? Thanks!
    • Oct 23 2007 | 12:12 pm
      Take a look at the 'phase vocoder' tutorials on this site. I am currently creating an user interface and am also using the waveform~ object to display sample location and selections! Take some time to study it and then simply add whatever you want. The cartesian version is a lot more subtle on your CPU so you could add lots and lots. I think the whole patch takes about 12% of my cpu and I am using a much older and slower laptop (pb g4).
      Have fun!