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iPad Pro latency question (strange)
Old 26th May 2019
  #1
Gear Head
 

iPad Pro latency question (strange)

I have an iPad Pro 10.5 running Auria Pro. I decided to loop back the audio interface for a test of latency. My audio interface is the Tascam iXR. I take a percussive waveform with obvious peaks, and then record through the looped back interface. The interface has a sample rate of 44.1 K. I do see the monitor lights of the interface’s input blink when they should.

Here is the part that does not make any sense to me. The latency comes out to about 150 samples, which I think is around 3 ms. This figure seems way too low. I ran a latency check app which came out to be 8 ms round trip time, outside of the additional latency that would of been introduced with Auria Pro.

What are your thoughts?

Thanks.

Oh yes, in order to get it to record in this way, I have had to turn on software monitoring, even though my interface has this feature in hardware. This part I also do not understand.

Last edited by r010159; 26th May 2019 at 11:09 PM..
Old 27th May 2019
  #2
Lives for gear
 
Moonwhistle's Avatar
 

Latency is weird with iOS.

But isn't Auria compensating the input latency in this scenario?
Old 27th May 2019
  #3
Gear Head
 

Quote:
Originally Posted by Moonwhistle View Post
Latency is weird with iOS.

But isn't Auria compensating the input latency in this scenario?
I did not think of this. So if it is compensating for the audio interface, then the 3 ms has to include the software itself. Yes? So in this case, *maybe* a more accurate value for everything in total is 3 ms + 8 ms, which ends up as about 12 ms. Just a thought. I will check Auria Pro for this possibility.

Update:

I found out that rhe driver should report the latency to the host app. Guess this is what Auria is using. The only thing that it cannot account for is the delays introduced by Auria itself. However, just for sh*ts and giggles, I ran this nice latency checker on the Mac that is also attached to the interface. It first reported that the driver of the audio interface is reporting the wrong latency. Then it came up with that 8.2 ms value. There must be a way to disable the auto latency correction made by Auria so more accurate tests can be made.

Take a look at this quote:

“Record Latency Adjustment – Enter a time value, in samples, to shift recorded audio earlier during recording. Auria automatically attempts to detect the hardware latency of the attached audio interface (both internal or USB interfaces), and then compensates for it so that recorded tracks line up correctly. If a particular interface either doesn’t report its latency, or the reported latency is incorrect, use this setting to manually compensate and have Auria shift recorded tracks by the amount entered. To determine an interface’s internal latency a Loop-Back test should be performed (see below).”

Last edited by r010159; 27th May 2019 at 01:47 AM..
Old 27th May 2019
  #4
Lives for gear
 
Moonwhistle's Avatar
 

Quote:
Originally Posted by r010159 View Post
I did not think of this. So if it is compensating for the audio interface, then the 3 ms has to include the software itself. Yes? So in this case, *maybe* a more accurate value for everything in total is 3 ms + 8 ms, which ends up as about 12 ms. Just a thought. I will check Auria Pro for this possibility.

Update:

I found out that rhe driver should report the latency to the host app. Guess this is what Auria is using. The only thing that it cannot account for is the delays introduced by Auria itself. However, just for sh*ts and giggles, I ran this nice latency checker on the Mac that is also attached to the interface. It first reported that the driver of the audio interface is reporting the wrong latency. Then it came up with that 8.2 ms value. There must be a way to disable the auto latency correction made by Auria so more accurate tests can be made.

Take a look at this quote:

“Record Latency Adjustment – Enter a time value, in samples, to shift recorded audio earlier during recording. Auria automatically attempts to detect the hardware latency of the attached audio interface (both internal or USB interfaces), and then compensates for it so that recorded tracks line up correctly. If a particular interface either doesn’t report its latency, or the reported latency is incorrect, use this setting to manually compensate and have Auria shift recorded tracks by the amount entered. To determine an interface’s internal latency a Loop-Back test should be performed (see below).”
If using a buffer setting of 128 samples & 44.1khz the latency should be around 12ms round trip. I can't remember the exact number I get with 64 samples, it's around 7.3ms iirc.

I haven't used Auria in a while but I'll see what I get with it.
Old 28th May 2019
  #5
Gear Head
 

12 ms seems “respectable”. As you mentioned, the buffer size alone can contribute to this latency. Who knows what buffer size the testing software used.
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