iphone 6(64gb) latency

[anfirmor]

Ok hope this isn't to long.

I did some latency testing on my three ios devices. Iphone 5, iphone 6 and ipad mini with retina (2)

Test setup was two DPA4061 mics. One next to iphone mic, one inside headphones. Mics into mixing desk and each the insert of each channel into 20MHz dual sampling oscilloscope. Two metal bars to create impulse. Not hyper accurate using cursors on scope to find transient edges and the scopes ms readout but good enough for this.

Latency Results for iphone 5
MTD
2.5ms buffer 11ms
5.6ms buffer 17ms
11.1 21ms

Garageband
No adjustments 17mS

IK Mic Room
Fast 17ms
Ultra Fast 11ms

Latency Results for iphone 6
MTD
2.5ms buffer 12.5ms
5.6ms buffer 18.5ms
11.1ms buffer 29ms

Garageband
No adjustments 18.5ms

IK Mic Room
Fast 18.5ms
Ultra Fast 12.5ms

Latency Reults for ipad mini retina

MTD
2.8ms buffer 12.5ms
5.6ms buffer 18.5ms
11.1ms buffer 30ms

Garageband
No adjustments 33ms

IK Mic Room
Fast 18.5ms
Ultra Fast 12.5ms

Cubasis
128 30ms
256 35ms
512 46ms

Auria
128 13ms
256 18.9ms
512 30ms
1024 54.5ms
2048 101ms
4096 198ms


PHEW!
Clearly the iphone 5 is faster but not by as much as I thought. Also I don't think I'll be trying Cubasis without an audio interface with direct monitoring.

However

These results may be interesting but some possible bugs showed. For anyone who is tempted to use IK Multimedia Mic Room (really cool) then you must reboot your device after installation. otherwise selecting ultra fast latency has no effect. Dont know if this effects any other apps they do.

In MTD I found that when it is closed down completely or a new project is created the app always reverts to 5.6ms buffer, even if 2.8ms was the projects setting. 2.8ms may be displayed in the tools pop-up but until you select a different buffer size and then back to 2.8 nothing changes and it sticks on 5.6ms.
I saw this across all three devices so I suspect there is a bug. may explain the horrid latency I was getting on the iphone 6 test i did. Also the headphone level setting reverts to a default on fully closing the app.

One other MTD bug. If you try and use another app as an IAA track effect then the track pan pot is all screwed up, like it's wired wrong. 12 o'clock is too hot. Fully left is fine level wise but only in the left channel (obviously). Fully right fades the signal to silence. Tried this with Mic Room and Jamup Pro. Same thing. Also tried same apps in Cubasis IAA track effect slot and pans just fine. Another bug in MTD. Any chance of a fix pwnified?


What's interesting is that none of the results quite get under the 10ms mark where latency becomes less annoying. I'll be looking for an audio interface with direct monitoring for sure. Sonic Port VX is closest for features from a mobile perspective but no good for using those lovely DPA4061's.

Apologies for the long post.

[pwnified]

Wow, awesome. I've always meant to do this and post up the results. It looks like MultiTrack has a slight edge over some of the other 'competitors' (to be honest I've never really thought of them as competitors, and always welcomed more app developers).

So, the deal with buffer latency settings. There is only one buffer size for the entire device, and the first app to grab it wins, for as long as that app is running. This is why audiobus recommends to start it first, so it will have control over the buffer size.

This is why, when closing down multitrack completely, it reverts to a 5.6 (256 at 44.1khz) buffer. Some other app must be holding the 256 buffer size. When opening a song in multitrack though, it should display a popup with the actual hardware buffersize, irrespective of what the button says in the settings.

Thanks for pointing out the panning bug, that sounds like a good one. I'll look into that.

[anfirmor]

Fantastic. MTD is my favourite so it's great that the developer is listening. I just tried the following on iPhones and iPad. Totally closed all running apps. Reboot. Open MTD.

When the pop up appears it only displays 16bit, 44.1kHz. No mention of buffer settings. I suspect something is still not quite right. I'll check with the scope tomorrow.


Thanks.

[pwnified]

Ah, correction. When changing the audio hardware, like plugging/unplugging a headset, with a song open it should display the audio hardware buffer size in the popup.

[anfirmor]

Ok. I just tried this with the scope setup again. All observations via the scope screen.

Iphone 5
All apps closed.
Using internal mic.
Headphones plugged in.

Then Launch MTD.

Starts in 5.6ms buffer mode (256). Every time. Doesn't matter if it launches straight to a song or home screen, which I think depends on the state just before closure. If the app is totally shut down it starts in the 5.6ms (256) mode. Buffer settings are not connected to a song, or what the settings were when a song was created. So loading a song or different song won't change the buffer size.

There seem to be two actions that change this.

1. Going into the buffer settings and forcing a change, even if this is from 2.8 to another setting and back again. This forces the buffer size.

2. Unplugging and re-inserting the headphones. Then the pop up displays the buffer setting as it is currently set (in settings), this also forces a change of buffer size.


My point is that if, as a user, you aren't aware of this behavior and you start MTD with headphones plugged in then you've no way of knowing what mode you're in. Nothing tells you. Surely there is a way to force the hardware buffer to take up the values as they are in MTD settings as it fires up?

I tried this same test with IK Mic Room (on it's own) and it always fires up with whatever buffer selection you set it to. Even after a full app closure and opening with headphones already plugged in. Garageband just does it's middle of the road 256 samples whatever.

So, there must be a way of making the hardware take up the initial values at start up without user interaction. This isn't in any way knocking MTD. Lots of use use it because it just does the job really well. I wouldn't want any users thinking that the app had average latency due to a start up anomaly. Or like me, thinking there new phone is totally crap when it is, in reality, just a little bit crap.

All the best

I've not tried this with a USB interfaces yet. Maybe soon.

[pwnified]

Thanks for the bug report, I'll take a closer look. It sounds like a bug at first glance, if no other apps are open, there shouldn't be anything preventing the buffer size request from working.

[anfirmor]

Brilliant. Thanks pwnified. Great support as always.

[anfirmor]

Just as a sidenote.

Installed 4Pockets Meteor yesterday. Nice app (had it on winmobile ages ago) but even on it's fastest latency setting the delay is unmistakeable. No need to bench test this one I'm afraid as it's as laggy as Cubasis.

It would seem that MTDaw is the only real multitrack option if you don't have access to direct monitoring. Especially if you want to use iPad & iPhone.

Any news on an update/bug fixes pwnified?

ps. got hold of a Fender Slide audio interface. Fairy compact. 24bit 48kHz. One jack input. Lightning compatible and has direct monitoring. £49 from Amazon.

[martygras]

@ANFIRMOR - Great job on the tests. Nice to know what's going on.

@pwnified - Hoping to see some updates soon. Some bugfixes. Some added or improved features.

[pwnified]

Pity that some app developers just can't figure it out. However I don't blame them, CoreAudio is a very tricky beast to get it right.
I've confirmed, and fixed for the next update, the "initial startup buffer size bug".
Still looking at the panning bug, it seems to work with some apps and not others. For me, the panning works for most of the range, just not fully panned to the right, in the JamUp app. Other apps are fine, such as the AUFX apps, and pan works across the whole range. With both mono and stereo tracks.
Unfortunately the update won't contain some of the advanced features I was working on, they will have to wait for another time. So the next update will be mostly a maintenance release, with, hopefully, one nice new feature, if all goes well =)
Within the next 2 weeks, I think.