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What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.
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CPU spikes on the iPad 6th gen
Hello crowd!
I was checkin' the fresh Vantage Electric app with my usual set (Keystage, AUM, iLectric replaced by VElectric, SampleTank, Korg Module, and Model D. Normally this set (with iLectric) works for me flawlessly. Using VElectric I've got DSP spikes up to more than 150% and sound drops using it with other sounds (layered), and some drops using as the only sound. Battery level dropped to 88% (still charged with original cables and power adapter. Then I closed everything, switched to the airplane mode, and opened an app called Lirum Info. While charging I noticed the untypical behavior of the CPU, pictured on screenshots.
Did anybody experienced something like this?
Comments
Such measurements don't indicate anything useful in iOS. iOS not like desktop operating systems. It throttles back CPU's to manage heat and battery usage, in ways that are unpredictable. CPU percentage in use is a function of processing power available at any one time. It doesn't mean much of anything.
Sound dropouts, crackling, and UI glitches do. There are many things that can cause this, but the most important is buffer size - or latency as some apps call it. Lower buffers = lower latency = higher CPU usage. Try raising the buffer settings in AUM (first quit everything and reboot your iPad) to see if the crackles go away.
If higher buffers stop the crackles, then it's possible that Vantage is just a CPU hog. If it doesn't then it's possible that Vantage is eating up too much memory.
My suggestion is to forget the CPU meter. Focus on the most obvious culprit - the new guy - Vantage. It could be, since its a sample based instrument, that it's simply overloading memory or is inefficiently coded.
I have one.
I have issues in AUM at times. But they fade quick.
My gen6 handles pretty much everything as long as I don’t push it too hard. I’d like an iPad I can really push to the limits, think like 4x power compared to what I can safely do with the gen6 will be enough for me...GeoShred AU gives me trouble sometimes unfortunately
My 6th gen is still solid although it is starting to show age in NS2 with more than 6 tracks and a few apps really push it in AUM like Factory and Aparillo. I will upgrade in the next year but its not that bad if you know whats too much for it.
@ wim and RUST( i )K
thank you for replies
I'm announcing a detailed investigation of this case. The names of the guilty will be announced.
Now, more seriously (never to the dead-end), I know some rules of changing buffer - I'm using IPad as the only source in my live keys rig. But I wonder what's happening in iOS when I turned on the airplane mode, had only one app on, was charging the unit and looked at the screen (at home I'm doing everything with the wi-fi and cellular on, to be sure, that I still have a reserve of CPU/memory, then during rehearsals?/gigs, I'm switching them off).
To me, iOS or "proud" iPadOS is phull of mysterious ambushes.
I want to say, that our music app developers are kind of heroes. They want to make the best sounding/working thing, but they have to fight with the doin' the dirty from System upgrades. All of them! WIn, Mac, iOS.
Well said man.
It's most likely that iOS is simply deciding that it doesn't need all available processing power and has therefore switched off some cores to save power. Your monitoring app has no information to work with other than the percentage of CPU usage available at that time. It's a meaningless measure.
However, there are also many, many things that can be happening (or trying to happen) in the background even with airplane mode on. If you look at settings > background app refresh, you'll see how many apps have been told that it's OK to try to update themselves even when not in use. They probably don't know the internet isn't available until they try. So, one or more of them might be waking up at any time, trying, timing out, failing ... leading to background CPU use. That use % is magnified if CPU is dialed back. Then iOS may decide it needs more capacity and brings it back, causing the % to fall. The same can go for things like checking for email.
That is true. But in this case you're making a mountain out of a molehill. That CPU measurement is meaningless - except that it could be a way of looking for further optimizations, such as switching off background updates that you don't need.
You could try things like temporarily removing email accounts, turning off background updates, etc. one at a time to see if you can find one of them the accounts for the CPU spike, though. That might be useful.
Most, if not all cpu spikes I’ve been seeing are due to graphics interfering with audio. When I have one app foregrounded and others working in the background there’s no spikes but as soon as I swipe between apps massive spikes appear. If average cpu usage is around 65-70% it often results in audio dropouts. Especially when accessing some app’s menu pop overs (samplr).
Thank you very much. Your answer gave me some to think. Anyway, I feel, that upgrade will be good protection. I hope Air'll be Okay.
You're right! Spikes while changing apps. Isn't ridiculous?
Sometimes it's getting funny, eg. really huge spikes of DSP (even 1500%) in AUM, when I'm changing pianos in iLectric (especially changing from/to Dyno Piano 2.
I think that the whole thing on iOS/iPadOS is still a baby. But baby which deserves big attention.
I wouldn’t say it’s a baby, more like a teenager with plenty of power needing management. 😂
I’ve successfully played live with some 4/5 apps hosted in Audiobus without issues but I avoid switching screens and always stay on the app I can’t map my controllers to. Everything else is mapped to midi controllers including session loading.
Great phrase!