Input gain setting doesn't "stick" when running Loopy with Audiobus

Hi there all. I've got Loopy running as the Output in Audiobus. If I try to change Loopy's input gain, the setting doesn't "stick": as soon as I leave the Settings screen, the input gain goes back to its previous value. This seems to happen no matter what is in the Input or FX slots of Audiobus (and in fact it happens when there is nothing at all in these slots).

There is no problem when Loopy is running standalone (i.e. without Audiobus).

I'm running the latest versions of Loopy and Audiobus on an iPod touch 5th generation. (Technically I'm using the Loopy HD universal binary, previously purchased on an iPad.)

Is this a bug or is there a reason for this behaviour?
Thanks, Jon


  • @flimdoo - as far as I know, the volume slider in Loopy is only for the build-in mic when recording directly in. Once loopy is in Audiobus, you have to control the output volume of the AB input Slot App and/or the AB Effects Slot App.

  • Thanks for the fast reply @Ganthofer. I record through an iRig plugged into the headphone/mic jack, and the "input gain" certainly controls the level of this input when Loopy is running standalone.

    The problem this causes for me is that sometimes when recording in Loopy (through Audiobus) I find that the input gain is set too high, causing distortion. (This seems to indicate that the input gain setting in Loopy is still used even if it can't be edited.) The only way I can edit the gain is to exit Audiobus and Loopy, launch Loopy standalone and tweak it there. Then launch Audiobus again. Perhaps I should be tweaking the gain "upstream" in Audiobus though?

  • @flimdoo - I believe you are right, loopy input gain slider works on analog input ( built in mic/headset jack).

    @Michael - I read a similar post some where here. I believe you commented on it, but can't find it.

  • I can't remember, @Ganthofer, but I can offer a suggestion: use the input gain slider in Audiobus' settings. On iOS, the app that is launched first gets the ability to mess with the audio session settings (which include the latency, sample rate and input gain). So, you won't be able to change the gain from Loopy if you've launched Audiobus first, but Audiobus has its own gain slider, and you can adjust it there.

  • Jon, I always assumed that what you describe is the intended behavior. When Loopy is routed thru Audiobus, the volume control is managed by Audiobus and ignores the Gain control in Loopy.

    Also Michael's explanation is good info, helps me because I didn't realize that the input gain settings are changing the actual hardware iOS input settings. So only one app has this capability at any given time: being the app that first accesses audio session settings.

  • Thanks all, that makes sense to me now. I hadn't realised that the gain control is actually at the hardware/iOS level. @Michael, is it possible to disable the gain slider in Loopy (e.g. grey it out or something) when another app like Audiobus has already grabbed the setting?

  • Annoyingly, @flimdoo, no! Apple don't provide us with a way to determine if we are allowed to change those settings - they don't even give us an error code if we try to set them. The only way to know is to attempt to change the value and then to read it again and see if it changed. Actually, so yes, I suppose I could hack something that changes the value slightly, sees if it's different, and if it isn't, disables the slider, but I'm actually planning on changing that system totally: Apple's own gain controls are utterly rubbish, because they only work with certain hardware. Sometimes it doesn't work at all. I plan to build my own auto gain control, with a slider added in if you turn the auto stuff off - then it's going to just apply a gain to the audio coming into Loopy, rather than relying on the crap system one.

    But I'm trying to get Loopy Masterpiece done, so Loopy is necessarily taking a bit of a back seat, as I don't consider it very urgent. (I know, I know...I released an update which added sharing - but that was to try to get the word out a bit more effectively =) Gotta earn a crust!)

  • Thanks @Michael! Really appreciate your help on this. Looking forward to Loopy Masterpiece!

  • P.S. would things be any different if I used an interface that plugs into the Lightning port instead of the headphone/mic jack? Is the input gain still used in this case?

  • I think it depends on the device - sometimes it supports gain controls, sometimes not. Not 100% sure about that, though.

  • @flimdoo - the 3 audio interfaces I own, all have their own hardware output gain knobs. I can't say that this is true for all external USB/Lightning audio interfaces. So typically one sets the hardware output gain to something below the clipping of the A/D. If you want/need to adjust it further, then you would need to us AudioBus or AUM (or similar) to do so.

  • OK thanks both!

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