Re: Audio cracks with the iPad 11"
Re: Audio cracks with the iPad 11"
- Subject: Re: Audio cracks with the iPad 11"
- From: Arshia Cont <email@hidden>
- Date: Thu, 15 Nov 2018 18:39:16 +0100
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> 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.
>
> -Dean
>
>> On Nov 14, 2018, at 4:52 PM, Martin Man <email@hidden
>> <mailto:email@hidden>> wrote:
>>
>> Hi Dean,
>>
>> What’s the
>> https://developer.apple.com/documentation/avfoundation/avaudiosession/1616499-samplerate?language=objc
>>
>> <https://developer.apple.com/documentation/avfoundation/avaudiosession/1616499-samplerate?language=objc>
>> reporting back to you?
>>
>> Martin (still unable to test on 11”)
>>
>>
>>> On 14 Nov 2018, at 14:24, Dean Reyburn <email@hidden
>>> <mailto:email@hidden>> wrote:
>>>
>>> Hi Pascal,
>>> I have found a possible solution for my recording (only) app which was
>>> giving distortion on iPad Pro gen 3 . My older versions record only at
>>> 44.1khz. When I change to 48khz the recording is perfect. Either sample
>>> rate works fine for my app, but I simply need to know during
>>> intitialization which to use.
>>>
>>> I’m still talking to Apple DTS about how to detect whether a device wants
>>> or needs 44.1khz or 48khz. There are no error returned when an iPad Pro gen
>>> 3 from AudioUnitSetProperty() or any other audio units call on iPad Pro 3
>>> when starting recording. The iPad Pro 3 accepts 44.1khz and confirms that
>>> it can do this sample rate with AudioUnitGetProperty() even though the
>>> recording is distorted.
>>>
>>> So far I have not found how to detect the “default” or “native” recording
>>> sample rate for a device if such a thing exists.
>>>
>>> -Dean
>>>
>>>> On Nov 14, 2018, at 5:02 AM, Flavio Antonioli <email@hidden
>>>> <mailto:email@hidden>> wrote:
>>>>
>>>> Pascal,
>>>>
>>>> we have also received reports from some of our users of audio distortion
>>>> on the new iPad Pro. We too are using RemoteIO.
>>>> We don't currently have a device to test with so I wasn't able to
>>>> reproduce the issue.
>>>>
>>>> Flavio.
>>>>
>>>> On Tue, Nov 13, 2018 at 9:00 PM <email@hidden
>>>> <mailto:email@hidden>> wrote:
>>>> Message: 2
>>>> Date: Tue, 13 Nov 2018 16:43:53 +0100
>>>> From: Pascal Douillard <email@hidden
>>>> <mailto:email@hidden>>
>>>> To: email@hidden <mailto:email@hidden>
>>>> Subject: Audio cracks with the iPad 11"
>>>> Message-ID: <email@hidden
>>>> <email@hidden">mailto:email@hidden>>
>>>> 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
>>>>
>>>> ------------------------------
>>>>
>>>> Subject: Digest Footer
>>>>
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>>>> ------------------------------
>>>>
>>>> End of Coreaudio-api Digest, Vol 15, Issue 94
>>>> *********************************************
>>>>
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>>>
>>> 1-888-SOFT-440 or 1-888-763-8440
>>> Reyburn CyberTuner, Inc.
>>> http://www.cybertuner.com <http://www.cybertuner.com/>
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>
> 1-888-SOFT-440 or 1-888-763-8440
> Reyburn CyberTuner, Inc.
> http://www.cybertuner.com <http://www.cybertuner.com/>
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