iOS 11 roundtrip latency not short enough (around 20ms)
I have some general questions regarding roundtrip audio latency under iOS with a iPad.
I had informed me quite a bit in advance about this topic.
(Apogee support, various forums, also here: > http://superpowered.com/latency)
And the general consensus was that one can run audio apps in general EASILY! with a (very,...maybe not insanly) low roundtrip latency of bellow 10ms. between 6/7ms to 12ms. Most said you can run it around or bellow 10ms. It was sait to be "ready for primetime", it is possible to really use this stuff in a live setting...etc... there is no perceivable latency... maybe even lower than some/ many PC based systems.
Now I bought a INSANELY! powerful iPad Pro 10.5 which, by specs outperforms my MacBook Pro (Early 2011) by a large margin(?!). I primary bought this device to use for live playing and tracking Guitar, using a iPad Pro live as well as for practice (timing) instead of a cheap, but still more expensive and inferior Multi FX and a DAW on my MacBook Pro.
HOWEVER: > it seems to be impossible to use the iPad and Bias FX, or Garageband or both via inter App Audio with a reasonably low latency!
I was quite surprised by that... is this New???
I am using a iPad Pro 10.5 with iOS 11 + Apogee Jam 96k + Bias FX, Garageband (all latest version as of 30. Nov 2017) headphones output.
So my questions are:
is apple to blame here? > was it better with older devices and iOS 9 / 10??
Is this a problem with iOS 11?
Is this a problem with the newer (2017) iPad Pro models?
Will this most likely improve (= shorter latency) (again?) with further updates?
I did some extensive testing*....
Here are my results:
In most cases I will have a roundtrip latency of around 20ms... maybe even 25ms...
(Garageband has a (fixed?) buffer of 256 "frames", Bias FX probably uses a buffer of 128 "frames")
If I am lucky I might get a bit lower than 20ms > 17ms with Bias FX only.
I also tested roundtrip latency with a app called "fiddlicator" which is basically an impulse response loader, which lets you choose various buffer frame sizes. ( I guess this is not the same as buffer SAMPLE size?)
@ 64 frames buffer = 15ms
@ 128 frames buffer = 18ms
@ 256 frames buffer = 25ms
IDAM > "Inter device audio midi" through lightning cable roundtrip test:
I let a MIDI track in Logic Pro X send MIDI through lightning cable to garageband "Piano">Audio back into Logic through the lightning cable recorded on new a track.
the audio arrived 10ms to late compared to the original MIDI track.
Shouldn't Logic Pro X "know" about this latency and compensate for it? (> Plugin latency compensation)
Yes... this is not insanely high.... but for me, for playing guitar "through it" it is just to much!
In most cases I will listen to speakers or a p.a. system… so that is an additional 3-5ms in most cases.
For comparison: On my Mac I always (since years) run @ a buffer size of 64 which gives me a roundtrip latency of around 6.5 ms.
- I did record my Guitar through a DI Box. One path went straight to my Audio Interface>Logic Pro X.
the "link out" of the DI Box went through a Apogee Jam 96k into iPad Pro>Audio App> Headphones out> Audio Interface>Logic Pro X. This way I could measure/compare the (additional) roundtrip latency caused by the iPad.
I was always using lowest buffer settings in Bias FX, closed all apps before starting a single audio app)
last but not least:
here is a cool site where you can test your hearing with various blindtests. You can also test if you can hear/feel a latency of 10ms/20ms -> http://www.audiocheck.net/blindtests_timing_2w.php?time=10