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

Kristofer Hagbard kristofer.hagbard at gmail.com
Mon May 13 21:09:43 CEST 2013

I had the same problem with cpu usage peaking when the patch was silent on the rpi with pd 0.43-something (whatever was in the standard rpi repos) Turned out it was the [hip~] that was causing the problem. (I used two [hip~ 5] before the [dac~] and simply removing them completely solved the problem)

The [hip~] bug might be solved in the 0.44-3 though I have not tested it yet.


On May 5, 2013, at 18:42 , Dan Wilcox <danomatika at gmail.com> wrote:

> 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:
> <Screen Shot 2013-05-05 at 12.40.14 PM.png>
> 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
> @danomatika
> danomatika.com
> robotcowboy.com
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