Audiobus: Use your music apps together.

What is Audiobus?Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.

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Samples rates on iPad Air 3 and similar devices - stuck or not

I was having a closer look at i*OS DAWs and the sample rates they allow on my iPad Air 3.

  • Cubasis 3 supports 44.1k, 48k and 96k, but is stuck at 48k on this iPad

  • BeatMaker 3 offers 44.1k and 48k, but is stuck on 48k

I was expecting this to be the normal behavior, but:

  • Loopy Pro offers 44.1k, 48k and 96k in the settings, does not get stuck at 48k, but the files are exported as 48k. It does not work and does not show this, @Michael

But then, I noticed this:

  • Auria Pro offers 44.1k, 48k and 96k when creating a new project and this actually works!
    I can export files at 96k on my iPad Air 3!

And again:

  • MultiTrack DAW offers 44.1k, 48k and 96k when creating a new project and this actually works!
    I can export files at 96k on my iPad Air 3!

And finally:

  • nanostudio 2 offers 44.1k, 48k and 96k even at mixdown and this actually works!
    I can export files at 96k on my iPad Air 3!
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Comments

  • What makes Auria Pro, MultiTrack DAW and nanostudio 2 so much superior over the other DAWs?!?

    Honestly, I thought that it is simply not possible to change the sample rate on an iPad Air 3 and similar devices, without a connected audio interface.

    But those three DAWs simply work perfectly fine!

  • edited January 19

    Nothing makes either of them superior... they are all stuck @48k (which is device specific). Some host will make it noticeable, telling you that you’re unable to switch, other host will look like they are switching successfully (f.e. 44.1k button highlighted, which is false), but in all cases they’re actually running @48k.
    This can only be changed with an interface attached that supports variable rates.

    Exporting a project at specific rate is a whole different topic... some hosts allow you to specify this (basically up sampling during the render) others will export at project rate, having no available preference (which is 48k on that device).

  • tjatja
    edited January 19

    @0tolerance4silence said:
    Nothing makes either of them superior... they are all stuck @48k (which is device specific). Some host will make it noticeable, telling you that you’re unable to switch, other host will look like they are switching successfully (f.e. 44.1k button highlighted, which is false), but in all cases they’re actually running @48k.
    This can only be changed with an interface attached that supports variable rates.

    Exporting a project at specific rate is a whole different topic... some hosts allow you to specify this (basically up sampling during the render) others will export at project rate, having no available preference (which is 48k on that device).

    Hmm.
    Interesting, thanks!
    Sad thing, I was already so happy 😅

    So, Auria Pro, MultiTrack DAW and nanostudio 2 are upsampling at export?

    Is there any way to check, if an audio file was upsampled?
    Doubling of each sample, or something?

    I may better ask the developers...

  • edited January 19

    @tja said:
    Is there any way to check, if an audio file was upsampled?
    Doubling of each sample, or something?

    Up sampling can be as trivial as simply converting audio file to a higher rate. F.e in AudioShare you can convert a 44.1k/16bit audio file to 96k/32bit (which won’t make it sound ‘better’)

    In practical terms up sampling during export can be beneficial because certain audio processing can utilise the additional rate/depth increase. (F.e most UAD plugins do conversion in real time, process the audio at higher rate and then convert it back to project rate, or some highend plugins offer oversampling to do the same, resulting better accuracy / sound). Exporting at higher rate therefore may force some plugins to do their processing ‘better’. But since we are talking about iOS (lack of standards, documentation, consistency) I wouldn’t be so sure about how much you actually gain. I’m sure some hosts /plugins handle it right, and I’m sure others don’t... also these things require a very keen ear/listening environment to pick up the differences... so imo total overkill on iOS generally.

    You can check your rendered audio in any editor (f.e AudioShare) to confirm its properties.

  • @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    I think, that would depend on the method used for upsampling, as I wrote, maybe all samples just get doubled - and this could surely be seen in such a file.

  • Added to my todo list to investigate @tja

  • @tja said:
    @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    I think, that would depend on the method used for upsampling, as I wrote, maybe all samples just get doubled - and this could surely be seen in such a file.

    You don't want to double the samples to upsample. The pretty standard way to do this is to insert the needed number of zeros between each original sample to get the desired upsample factor. You then filter the resulting stream with an appropriate lowpass filter. The lowpass filter takes out the discontinuities introduced by the insertion of the zeros. You also have to scale the resulting samples because the adding of the zeros scales the energy in the signal by that ratio.

    If in the generation of the audio you had higher frequency content, then you could see the difference in the files. For example, if you had a non-linear element that aliased the signal when it was generated at 48kHz. That aliasing would still be there if you upsampled after generating the signal. If the original signal were generated at 96kHz, then you would lessen the aliasing and might even eliminate it, so the resulting file would have different frequency content below 24kHz and might have frequency content above 24kHz that wouldn't be there in the upsampled file.

    I suspect that it would be possible to see differences in the transients and attack of audio recorded at higher sample rates too. But, It'd take some experimentation to see what the differences looked like versus audio recorded at a lower sample rate and then upsampled. It would probably be interesting to look at recordings of hits to the bell of a ride cymbal to see what they looked like.

  • tjatja
    edited January 20

    Very interesting details, many thanks @NeonSilicon !

    Sadly, I still have no audio interface.

    I bought one, but chould not change the rate of DAWs with it...
    Any recommendation for a "basic" interface that allows rates up to 96 or 192 k?

    Either for Lightning connection, or for a Dock that the iPad connects to over Lightning to USB...

  • @tja said:
    Very interesting details, many thanks @NeonSilicon !

    Sadly, I still have no audio interface.

    I bought one, but chould not change the rate of DAWs with it...
    Any recommendation for a "basic" interface that allows rates up to 96 or 192 k?

    Either for Lightning connection, or for a Dock that the iPad connects to over Lightning to USB...

    You can get a Soundblaster Play which will let you control sample rates:

    https://smile.amazon.co.uk/Creative-Sound-Blaster-Resolution-External/dp/B073KTPNDR/ref=sr_1_3

  • @richardyot said:

    @tja said:
    Very interesting details, many thanks @NeonSilicon !

    Sadly, I still have no audio interface.

    I bought one, but chould not change the rate of DAWs with it...
    Any recommendation for a "basic" interface that allows rates up to 96 or 192 k?

    Either for Lightning connection, or for a Dock that the iPad connects to over Lightning to USB...

    You can get a Soundblaster Play which will let you control sample rates:

    https://smile.amazon.co.uk/Creative-Sound-Blaster-Resolution-External/dp/B073KTPNDR/ref=sr_1_3

    Fantastic, many thanks!

    Ordering now...

  • Afaik all focusrite interferes will go up to 96k (again imo total overkill), I would say most dedicated semipro, prosumer interfaces will, but these specs are fairly easy to find out.

  • tjatja
    edited January 20

    @tja said:

    @richardyot said:

    @tja said:
    Very interesting details, many thanks @NeonSilicon !

    Sadly, I still have no audio interface.

    I bought one, but chould not change the rate of DAWs with it...
    Any recommendation for a "basic" interface that allows rates up to 96 or 192 k?

    Either for Lightning connection, or for a Dock that the iPad connects to over Lightning to USB...

    You can get a Soundblaster Play which will let you control sample rates:

    https://smile.amazon.co.uk/Creative-Sound-Blaster-Resolution-External/dp/B073KTPNDR/ref=sr_1_3

    Fantastic, many thanks!

    Ordering now...

    In my region of Old Europe, only this is available:

    Creative Sound Blaster Play! 4 External USB-C DAC and Sound Adapter with VoiceDetect Auto Mic On/Off, Two-Way Noise Cancellation, Bass Boost/Dynamic EQs, for Video Calling on Windows PC

    Sadly, I have no USB-C port free on the Dock.

    @0tolerance4silence I will check out those Focusrite as alternative

    This is not to produce music at 96k or 192k, but for any experiments around sound and spectrometry and such.... or to check if and how I can detect upsampled audio files

    EDIT: I found version 3... it is ordered

  • edited January 20

    @tja said:
    @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    Add an AUv3 that can generate a, say, 40 kHz sine wave. Mixdown. Open exported file in a spectrum analyser. If the spectrum contains exactly one peak at 40 kHz, your mixdown has not been upsampled, but truly mixed and exported at 96k. Simple :)

    (if it actually only mixes at 48k, then in the best case, the exported file should be completely silent. In other cases, you'll probably see several peaks from aliasing ("down-mirroring") of the "supposed" 40 kHz sine wave).

  • @SevenSystems said:

    @tja said:
    @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    Add an AUv3 that can generate a, say, 40 kHz sine wave. Mixdown. Open exported file in a spectrum analyser. If the spectrum contains exactly one peak at 40 kHz, your mixdown has not been upsampled, but truly mixed and exported at 96k. Simple :)

    (if it actually only mixes at 48k, then in the best case, the exported file should be completely silent. In other cases, you'll probably see several peaks from aliasing ("down-mirroring") of the "supposed" 40 kHz sine wave).

    Ah, great...

    Many thanks!
    Will try this out at the weekend - interface may come tomorrow

  • @tja said:

    @SevenSystems said:

    @tja said:
    @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    Add an AUv3 that can generate a, say, 40 kHz sine wave. Mixdown. Open exported file in a spectrum analyser. If the spectrum contains exactly one peak at 40 kHz, your mixdown has not been upsampled, but truly mixed and exported at 96k. Simple :)

    (if it actually only mixes at 48k, then in the best case, the exported file should be completely silent. In other cases, you'll probably see several peaks from aliasing ("down-mirroring") of the "supposed" 40 kHz sine wave).

    Ah, great...

    Many thanks!
    Will try this out at the weekend - interface may come tomorrow

    OK, but the interface should have nothing to do with export/mixdown :) it's a pure software operation...

  • tjatja
    edited January 20

    @SevenSystems said:

    @tja said:

    @SevenSystems said:

    @tja said:
    @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    Add an AUv3 that can generate a, say, 40 kHz sine wave. Mixdown. Open exported file in a spectrum analyser. If the spectrum contains exactly one peak at 40 kHz, your mixdown has not been upsampled, but truly mixed and exported at 96k. Simple :)

    (if it actually only mixes at 48k, then in the best case, the exported file should be completely silent. In other cases, you'll probably see several peaks from aliasing ("down-mirroring") of the "supposed" 40 kHz sine wave).

    Ah, great...

    Many thanks!
    Will try this out at the weekend - interface may come tomorrow

    OK, but the interface should have nothing to do with export/mixdown :) it's a pure software operation...

    Uhmm.

    With the interface, I should be able to export a real 96k audio file... not upsampled.

    If not, I don't need an interface 😅

  • @tja said:

    @SevenSystems said:

    @tja said:

    @SevenSystems said:

    @tja said:
    @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    Add an AUv3 that can generate a, say, 40 kHz sine wave. Mixdown. Open exported file in a spectrum analyser. If the spectrum contains exactly one peak at 40 kHz, your mixdown has not been upsampled, but truly mixed and exported at 96k. Simple :)

    (if it actually only mixes at 48k, then in the best case, the exported file should be completely silent. In other cases, you'll probably see several peaks from aliasing ("down-mirroring") of the "supposed" 40 kHz sine wave).

    Ah, great...

    Many thanks!
    Will try this out at the weekend - interface may come tomorrow

    OK, but the interface should have nothing to do with export/mixdown :) it's a pure software operation...

    Uhmm.

    With the interface, I should be able to export a real 96k audio file... not upsampled.

    If not, I don't need an interface 😅

    If by "export" you mean "click a button and write a file", then this is completely independent of any interface. An interface is only needed if you want an analog (or digital) live signal going out of your device.

    The "export" feature of a DAW couldn't care less about the audio hardware. Heck it could offer you to export at 1024 MHz and it should be perfectly able to do so. :)

    Maybe I should've read the whole thread 😬

  • tjatja
    edited January 20

    Now I am confused, @SevenSystems ... more than usual.

    I thought, that attaching an audio interface with a variable sample rate would allow to set / change the DAW to other (and higher) sample rates than normally.

    For example, my iPad Air 3 is stuck at 48k...

    I want to run a project in a DAW at 96k, when such an interface is connected.

    Meaning, the whole project and resulting export files would be real 96k files with real 96k content, not upsampled by the DAW from 48k.
    It could also contain content above 22,05k....

    If this is not the case, I have no need for such an interface... in this case, I cannot run a project at other rates than 48k on this iPad.

    Or?!? 😳

  • It's going to depend on the host to set the sample rate to a different setting than the audio engine on iOS to render a file with a different sample rate than the current audio session for the iPad is set at. It's possible, but I don't know if any do this. Because of the way the AVFAudio system is set up on iOS, it seems that most DAW's run with what the system does for live processing. Having an external interface hooked up that can change its sample rate via software configuration allows the DAW to request a sample rate change of the AVAudioSession by calling the setPrefferedSampleRate function. This call might return with false even with an external interface if other things in the audio system are in control.

    The docs for what is happening kinda start here https://developer.apple.com/documentation/avfaudio/avaudioengine/ with the AVAudioEngine and here https://developer.apple.com/documentation/avfaudio/avaudiosession with the AVAudioSession. The first thing to note is that the session is a shared instance. Everything goes through the same session.

    You can see in the AVAudioEngine that it is possible to set the engine into manual rendering mode with a specified audio format, AVAudioFormat, and then render the graph with that. I've never messed with this part of the engine, so I don't know the specifics, but there are probably some complications in the graph for dealing with nodes that are set at different sample rates than the specified format. You would probably need to insert sample rate converters on audio file playback nodes and input nodes for example (if you were using these nodes in your host).

  • @NeonSilicon I may be off here, but I remember to constantly read about "changing the sample rate" after attaching an audio interface, in this very forum.

    There need to be people who own and use an interface and simply know, if an i*OS DAW can then run at 88.2k, 96k or higher- producing audio files such a native resolution, not upsampled.

  • @tja said:
    @NeonSilicon I may be off here, but I remember to constantly read about "changing the sample rate" after attaching an audio interface, in this very forum.

    There need to be people who own and use an interface and simply know, if an i*OS DAW can then run at 88.2k, 96k or higher- producing audio files such a native resolution, not upsampled.

    Yes with an audio interface attached you can run your DAW at any sample rate supported by that interface.

    I think the confusion arose because you can render to different sample rates even without an interface attached, but in order to actually run your projects at a sample rate other than 48khz you need to have an interface connected on the newer devices.

  • @tja sorry if I've been confusing. In a nutshell:

    • When running "live", your DAW either needs to run at a sampling rate that your interface supports (simplest scenario), or it needs to automatically resample whatever internal project sampling rate it uses to one of the supported rates of the interface before it pipes the audio to the output. Any "reasonably well made" DAW should still be able to run a project at any sampling rate whatsoever and then convert at the output. I mean, conversion needs to take place anyway because no DAW in the world runs at 16-bit internally, for example. (at least I hope so). So if conversion has to happen for the bit depth anyway, then why not for the sampling rate. (I'm talking out of my perfectionist tail though!)

    • Mixing down (rendering, exporting, etc.) a project is an entirely "virtual" mathematical operation that has nothing to do with an interface. Most audio file formats support any sampling rate (44.1 kHz, 48 kHz, 96 kHz, 20000*π kHz, etc.), so any reasonable DAW should be able to export the project at whatever sampling rate has been set for that project, even if NO audio interface or any audio hardware at all is available.

    Again I'm talking theoretical here, I'm not extremely experienced with developing DAWs. But I do know that if I developed one from scratch*, the above would be true ;)

    *I have but I have no idea when it'll be finished :(

  • Yeah to what @richardyot said. Having an external interface hooked up to your iPad can allow for running sessions at different sample rates if the interface supports different sample rates. I believe most do, but there are going to be some that don't. These sessions are not likely to be upsampled but run at the native resolution the session is set to.

    I can tell you that with all of my interfaces when using AUM, Audiobus, and if I remember right every other DAW I've tested with, that the audio being passed to my AU's is running at the sample rate the session is set to. (This is true by default for GB since it is locked at 44.1kHz still if I remember right.)

    What I was mentioning in my above posts are the exceptions that can occur in both a positive and a negative direction. A host can manually render to a different rate than the running audio session. This could be useful in, for example, a mastering host. I don't know if anything does do this, but it is possible. The host could configure the session to run at one sample rate to generate the output audio file and still use a sample rate converter AU to connect to the output audio ports for monitoring at whatever the rate the overall iPad session is locked to.

    The other potential issue is that the system can refuse to set the sample rate to the one that the host is requesting even if the interface is capable of running at the requested sample rate. This would happen in the situation that some other software already had control of the audio session on the device. When this happens with AUM, it'll popup a dialog and warn you that the sample rate change didn't work. As a note. this happens to me in one situation on macOS too. When I launch GarageBand, it changes the sample rate on my interface to 44.1kHz and messes up everything else that is running on my system at 96kHz. Pisses me off every single time.

  • edited January 20

    I just made a 24bit 96khz recording/mixdown on my iPad-1 with the Alesis ioDock-1 o:)
    (in Multitrack DAW)

  • @Telefunky said:
    I just made a 24bit 96khz recording/mixdown on my iPad-1 with the Alesis ioDock-1 o:)
    (in Multitrack DAW)

    The question is, if MultiTrack DAW did upsample or not.

    Any content between 22.5 and 44.1 kHz?

  • Thanks @SevenSystems and @NeonSilicon

    I will see if I can check this with the interface, at 96k.

  • edited January 21

    @tja said:
    The question is, if MultiTrack DAW did upsample or not.

    Any content between 22.5 and 44.1 kHz?

    Well, there is content up to 48khz, according to half the sample rate.
    With the iPad One I just tracked the empty channel noise, later normalized to -6dB.
    The noise is fairly uniform up to 20khz, then there‘s a slope down to 25khz (quarter-circle shape) and the rest of the noise level is uniform again.

    I repeated the MTD test with an Air-1 and the ID22 (which is a true 96khz device), this time with a (clean) e-guitar via instrument input.
    Again there‘s content across the full spectrum, the decay of frequencies is as expected from a guitar (a 60 degree slope down up to 9 khz, the rest is uniform with 3 peaks, the most prominent at 39khz.

    I don‘t think it‘s upsampled, as MTD switches the interface to the desired sample rate (set in preferences), which can be heard by the negotiation clicks.
    But I have few ideas about the details of such spectrograms...

  • tjatja
    edited January 21

    @SevenSystems said:

    @tja said:
    @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    Add an AUv3 that can generate a, say, 40 kHz sine wave.

    Any recommendation for this?

  • @tja said:

    @SevenSystems said:

    @tja said:
    @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    Add an AUv3 that can generate a, say, 40 kHz sine wave.

    Anh recommendation for this?

    Sorry, I don't know of any... but there should be plenty!

  • wimwim
    edited January 21

    @tja said:

    @SevenSystems said:

    @tja said:
    @0tolerance4silence I meant if there is a way to check if an audio file was upsampled, instead of being exported correctly at a higher sample rate.
    Both files will of course show 96k ;-)

    Add an AUv3 that can generate a, say, 40 kHz sine wave.

    Any recommendation for this?

    iVCS3 comes with a separate Oscillator AUv3. I assume the sine wave is pure, but don't know for sure.
    miRack has many to choose from.
    The Oscillator by Jonatan Liljedahl. Free, but not AUv3.

    I seem to recall there being talk of a tone generator or two in this thread: https://forum.audiob.us/discussion/40529/post-your-spectrogram-discoveries-here/

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