[PD] High CPU usage when tracks are muted (Raspberry Pi)

Dan Wilcox danomatika at gmail.com
Sun May 5 18:42:05 CEST 2013

Even though you don't have audio coming out when you're muting, you're still doing dsp. You should put each channel in a sub patch or abstraction and use [switch~] to enable/disable that abstraction. This is super important with low resource machines. The best fix is to do a quick (10-5ms) fade in/out when muting/unmuting, then hit [switch~] so you don't get any clicks:

On May 5, 2013, at 12:12 PM, pd-list-request at iem.at wrote:

> From: Halfdan Mouritzen <halfdan at robothangarskib.dk>
> Subject: [PD] High CPU usage when tracks are muted (Raspberry Pi)
> Date: May 5, 2013 12:11:56 PM EDT
> To: pd-list <pd-list at iem.at>
> Dear PD Friends,
> We are building a collaborative music sculpture, using five Raspberry
> Pi's to each run a seperate instrument / HID.
> Everything is very well, they each run a minimal Arch installation and
> boot up into PD without a GUI.
> One machine we are building at the moment, is just a very basic sample
> player - it has 8 tables with samples, that get played via a looping
> tabplay~.
> The machine works by simply muting and unmuting of the different
> channels - very basic.
> Now the problem is that when all eight tracks are unmuted the CPU
> usage is around 15-16 % - very fine, with lots of room for other
> activities.
> NOW, when one mutes channels, the CPU usage starts climbing and
> climbing, resulting in 95-100% usage when all the channels are
> muted...
> This results in lagging/glitching, when one tries to turn on channels again.
> The muting / unmuting is done through a simple *~ which gets set to
> either 0 or 1 with a line.
> I have noticed others have experienced this problem, but I haven't
> been able to find a solution to the problem.
> Hope somebody has a solution, as we are installing the machine at a
> music festival this week, and plan to open source all
> patches/sounds/build plans etc.
> All the best and keep on patching
> Halfdan & Jonathan

Dan Wilcox

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