Pascal,
Message: 2
Date: Tue, 13 Nov 2018 16:43:53 +0100
From: Pascal Douillard<[email protected]>
To:[email protected]
Subject: Audio cracks with the iPad 11"
Message-ID:<[email protected]>
Content-Type: text/plain; charset=utf-8
Hi everyone,
I have an audio app for iPad & iPhone and I have been getting audio cracks on
the new iPad Pro 11”. The cracks happen on speakers and on headphones on the USB-C
port but not when using bluetooth headphones like the Air Pods.
They do not happen on any of the other iPads or iPhone.
The audio engine is in C++ and is running in Core Audio using a single RemoteIO
unit. No extra audio libraries are used.
This is not related to the forced 48K sample rate of the iPad 11” as the app
runs fine with the same sample rate on other devices.
Anyone else has experienced the same? Thanks.
Pascal
First I don't have one of these yet, but I would imagine they work like
the rest of the USB IOS enabled products (i.e. Camera Connection Kit) in
that the device you are connecting with should be UAC (USB Audio Class)
or UAC2 compliant. It would not be forced into a resampled 48K sample
rate, but would work at the rate specified.
In the case of pops, cracks or distortion, this is usually a case of one
of two problems:
a) if the device is running Asynchronous then the host is either
rejecting the feedback pipe or not receiving valid frames and the device
is either underrunning or overrunning the samples.
b) If Adaptive or Sync then the device cannot pull the master clock into
the range to match that of the host and then the same problem of either
too many or not enough samples to maintain a consistent audio flow.
Thanks,
Gordon
--
J. Gordon Rankin
Owner and Chief Scientist
====== Wavelength Audio, ltd ======
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