MIDI Guitar 2 for iOS & Sample rate issues

Started by Vaultnaemsae, July 16, 2018, 09:12:28 PM

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Vaultnaemsae

Hi everybody,

I've been traveling lately and needed a small but relatively powerful rig so have been using an iPad Mini 4/iConnectAudio4+ tiny rig. All sounds are run in an iOS audio host app called AUM (by Kymatica). I've got Bias FX and various iOS softsynths which are fed by MG2 for iOS. Everything is controlled by the Softstep 2. Rigs don't get much smaller and it sounds really good. I've been getting some excellent results but am constantly confronted with the limitations of the iPad Mini 4's processing power. I had hoped to get Auria Pro DAW going in the iPad for recording projects but it seems like the iPad is already maxing out its CPU at current usage levels. I also brought along a GP-10 to test feeding it's analog outs into the iPad for virtual tunings, instrument modeling - but that's the next step. All very fun and compact but somewhat limited. One of the great things about the iConnectAudio4+ is that you can also add in a 2nd device - in my case a MacBook Pro - which will be able to handle the recording side of things a bit better than the iPad. It does take a while to set all these things up though.

One issue I have found is that when MG2 is active it forces AUM's sample rate to 48kHz - even if AUM was set at 44.1kHz when opened. This holds true for both iPad Mini 4 and an iPhone 7 Plus. However, it doesn't have any effect on an old iPhone 6 - it will happily stick to the selected sample rate. I understand that recent iOS devices (post-iPhone 6S devices?) default to 48kHz with no hardware attached. If I directly plug in a set of lightning headphones on any later device I can reset the sample rate to 44.1kHz without issue.

All this wouldn't be a big issue but one of the AUv3 synths I'm using (Syntronik iOS) has a problem with playing back in tune at anything other than 44.1kHz. IK Multimedia has reported it will be fixed in an upcoming app update so that will be one less problem.

Any thoughts on the sample rate issue? Why does MG2 force a sample rate change on the later devices?

Also, are there any iOS devices that can handle this kind of processing more efficiently? I noticed that even the iPhone 7 Plus with double the RAM and a more recent processor than the iPad Mini 4 freaks out when running more than 1 synth and has occasionally shown spiked DSP/CPU usage at over 800%  :-\

It has also occurred to me that the processes could be divided and shared between two iOS devices but I haven't really explored that at any great depth - yet.

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Rhcole

I have an iPad Pro 9.7 running iOS 11.4. I use both MG2 and Syntronik. I have had no issues with any program or synth with this setup thus far, including Mellotrons etc. I haven't checked my sample rates because everything works fine. So, I can't help beyond saying my setup works.

Vaultnaemsae

Hi rchole,

I'm guessing you are using Syntronik in standalone mode. That works for me too. Syntronik AUv3 is the problem area — And the MG2 sample rate hijacking thing. I'd love an iPad Pro but they're so big and expensive...I can't justify getting one right now. My Mini, despite its weaknesses, fits in my guitar case nicely.

Have you tried running any parallel guitar processors?
Vaultnaemsae's SoundCloud:
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Rhcole

Yes, standalone only. FYI, the 9.7 that I use is 2 1/2 years old. You can buy them pretty cheaply now and at 9.7 they are not that much bigger than a Mini.
I have loaded the iPad up with Fluxfx for regular guitar and then added multiple apps routed via Audiobus including MG2. I control MIDI volume with a foot pedal. It could easily have crashed but it works fine.

It has worked so well, it is changing how I look at guitar synthesis. I'm used to fighting dragons with an umbrella to get guitar synthesis to work. And here is a rig that is compact, sounds great, and just works. It tracks my odd chords and finger-picky playing with accuracy that is so close, I almost don't need it to be better. It's almost bewildering.


Vaultnaemsae

I may well look into an upgrade on your advice. Or I may dedicate guitar to one device and MG2/softsynths to another.

I've had problems with Flux FX. It freezes every time I put it in visualization mode.

I guess you have the MIDI Flow app? That was the only way I could get a virtual port from MG2 to set up as a savable/definable MIDI input in AB3.

It's pretty awesome except:
1. pitchbend on polyphonic events
2. chord structures with a semitone interval inside

If the developer ever makes iOS MIDI Guitar 2 into AUv3...well, that could be very interesting for us :)
Vaultnaemsae's SoundCloud:
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Brak(E)man

Quote from: Rhcole on July 17, 2018, 09:49:14 AM

I have loaded the iPad up with Fluxfx for regular guitar and then added multiple apps routed via Audiobus including MG2. I control MIDI volume with a foot pedal. It could easily have crashed but it works fine.
Slightly Ot but have you got Fluxfx to work with Audiobus ?
swimming with a hole in my body

I play Country music too, I'm just not sure which country it's from...

"The only thing worse than a guitar is a guitarist!"
- Lydia Lunch

Vaultnaemsae

Yes. Just tried it today after AB 3.1 was officially released...But Flux FX will not go out of visualization mode once selected and it runs the CPU ragged on the iPad mini.
Vaultnaemsae's SoundCloud:
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Vaultnaemsae

I guess it's also worth mentioning that MG2's Virtual MIDI Port now appears as a MIDI device/port in AB3 which makes setup a little easier. Now if MG2 patches would just remember the selected MIDI OUT...
Vaultnaemsae's SoundCloud:
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Brak(E)man

Quote from: Vaultnaemsae on July 26, 2018, 08:56:52 AM
Yes. Just tried it today after AB 3.1 was officially released...But Flux FX will not go out of visualization mode once selected and it runs the CPU ragged on the iPad mini.

Is AB3.1 an update ? From Audiobus 2 ?
swimming with a hole in my body

I play Country music too, I'm just not sure which country it's from...

"The only thing worse than a guitar is a guitarist!"
- Lydia Lunch

admin


Vaultnaemsae

I find AUM a bit more flexible than AB3. I can imagine some applications where using both in combination would come in handy.
Vaultnaemsae's SoundCloud:
https://soundcloud.com/vaultnaemsae