Re: Audio cracks with the iPad 11"
Re: Audio cracks with the iPad 11"
- Subject: Re: Audio cracks with the iPad 11"
- From: Pascal Douillard <email@hidden>
- Date: Thu, 15 Nov 2018 21:23:00 +0100
Hi everyone,
thanks for your replies.
We have made some progress on the issue as it seems that in spite of the
powerful brand new A12X cpu, the audio thread of our app seems to overrun the
cpu causing cracks. The same app runs fine on any other iPad or iPhone
(including the latest XR and X Max). We’ve been in touch with Apple that are
looking into it.
Pascal
> On 15 Nov 2018, at 19:39, Dean Reyburn <email@hidden> wrote:
>
> Hi Arshia,
> I use Apple’s Audio Tool Box, everything I need is included in:
>
> #include <AudioToolbox/AudioToolbox.h>
>
> I’m calling:
>
> AudioUnitSetProperty(), AudioUnitInitialize(), AudioOutputUnitStart() etc..
>
> -Dean
>
> PS It’s only the iPad *PRO* gen 3 that’s giving me issues.
>
> PSS Apple is asking for a demo program and to report this as a bug.
>
>> On Nov 15, 2018, at 12:39 PM, Arshia Cont <email@hidden
>> <mailto:email@hidden>> wrote:
>>
>> What service are you using to record your streams from RemoteIO? Extended
>> Audio File Services? Audio File Services? AVAudioEngine magic?
>>
>> Reading your posts I have to buy a 3rd generation iPad! :) But know that if
>> the system’s sample rate is at 48Khz and you are using 44.1khz, depending on
>> the recording service you use, additional converter services will be
>> introduced on the way to adapt services. And depending on your setup, it
>> will consume resources and if your BufferDuration is low then you get
>> glitches! Another source of glitch is of course if your Stream Formats do
>> not comply (which again depending on services used can introduce additional
>> cycle consuming converters that you don’t “see”).
>>
>> You can “see” them if you run your App on device and use Instrument’s “Time
>> Profiler”. Just take a sample of runtime during recording and find the
>> process that is taking too much time! Doing this you can sometimes find
>> amazing things under the hood that you are introducing without wanting or
>> not-recommended live DSP practices that you just missed (such as calling
>> Shared singletons which cause glitches if called in the audio thread).
>>
>> Curious to know what you find until I receive my new iPad! :)
>>
>> Cheers,
>>
>>
>> Arshia
>>
>>> On 15 Nov 2018, at 16:35, Dean Reyburn <email@hidden
>>> <mailto:email@hidden>> wrote:
>>>
>>> A follow up:
>>>
>>> My iPhone XS Av session has a sampleRate of 48khz, however this device
>>> records with a lot of distortion at 48khz. At 44.1khz the iPhone records
>>> perfectly.
>>>
>>> So I’m still searching for a way to determine a reliable distortion free
>>> recording rate on all devices. For now I can use 48khz only with the
>>> “iPad8,x” but that’s a hack and the wrong way to do this in the long run.
>>>
>>> FWIW I’m using the play and record av session type.
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