What is Audiobus?

Audiobus lets you connect apps

just like cables let you connect audio and MIDI equipment.


What can I do with Audiobus?

With Audiobus you can:

Play an instrument app into a live-looper

Multitrack record a drum sequencer and a synth together

Filter the output of an instrument app

Route a MIDI controller into a compatible synth app.

Or even use MIDI filter apps to manipulate midi messages, like splitting up a keyboard into multiple sections to control different sound generators.

…and use any other combination of compatible apps.

See the "APPS" button in the top left corner of the main screen for a directory of apps that work with Audiobus.


Getting started: Audio

Audiobus has three different modes: Audio, MIDI, and the Mixer. The default mode is audio. Audiobus sessions are set up by adding compatible apps to the main screen.

There are three positions that apps can be placed in, which allow you to create a pipeline of apps.

Input apps are a source of audio or MIDI.
Example source apps include SoundPrism Pro, Sunrizer, FunkBox and Figure.

Effect apps manipulate audio or MIDI.
Example effect apps include Echo Pad, JamUp Pro and Crystalline.

Output apps receive audio or MIDI.
Example destination apps include Loopy HD, MultiTrack DAW and GarageBand.

Some apps can be used in multiple positions, which means they can be an input, an effect or an output. Furthermore most audio input apps can also be MIDI receivers.

Tap a "+" button to add an app in one of the positions. A list of all compatible apps will be shown: Tap one to select it.

Launching Apps

Once you add an app to a slot, Audiobus 3 will try to load it. Apps that have not been optimized for Audiobus 3 will require you to manually launch them with a tap and Audiobus will prompt you to launch them into the foreground by displaying a 'Tap to Launch' label on top of the app icon. iOS will switch back to Audiobus once they're launched.

All other apps and Audio Unit Extensions will be launched into the background with no further interaction required. You can find new Audio Unit Extensions and apps that have been optimized for Audiobus 3 in the compatible apps directory, which is accessible by tapping on 'APPS' in the top left corner of the main screen.

If you don't own an app yet but it appears in your setup after you've downloaded a preset from another Audiobus user, the label will read 'Tap for App Store'. Tapping will then open up the App Store where you can purchase or download the app.

Afterwards, you can tap the app icon any time to switch to it.

Once all apps in a pipeline have been launched successfully, an active Audiobus connection is indicated by an animating lightstrip beside the connections.

The Audiobus Mic and Speaker

Audiobus provides a speaker destination and microphone source. The microphone source also works with audio input accessories.

The Audiobus microphone source can also come in handy if you want to record the live audio input as well as the output from another app. Audiobus will mix the audio together seamlessly.

Audiobus supports input from class compliant multi-channel audio interfaces. Depending on the audio interface, you may need a camera connection kit and a powered USB hub to use it with your iOS device.

When Audiobus recognizes a compatible multi-channel audio interface, a blue disclosure indicator will appear on the System Audio Input item. Tap this to select individual channels or channel combinations.


The MIDI Page

Audiobus 3 now features a MIDI page which lets you set up MIDI connections between external hardware MIDI controllers and apps compatible with Audiobus 3's MIDI system.

All apps that are compatible to Audiobus 3's MIDI system will only send and receive MIDI data to other Audiobus MIDI compatible apps. That means no more double notes, no searching for the proper way to set up connections or apps automatically connecting to MIDI sources or destinations that they should not connect to.

Audiobus 3's MIDI page also features a new class of apps which can act as MIDI effects. With MIDI effects we've made it simple to split areas of an external keyboard, transpose incoming MIDI notes or add a MIDI based delay. Some MIDI effects apps (like the midiFlow filters apps) can be instantiated multiple times. That means you can add them to multiple MIDI pipelines at the same time.

All apps that are added to the output slot on the MIDI page will automatically be added to the input slot on the Audio page.

You can find an overview of currently available MIDI effects in our compatible apps directory, which is accessible by tapping on 'APPS' in the top left corner of the main screen and selecting the MIDI category.

Here's a quick video introduction to what you can do with MIDI in Audiobus 3


The Mixer

Audiobus 3 now gives you access to an easy to use mixer for every audio input. It comes with the standard features you expect: muting, pan, gain control and of course a simple VU meter.

If your audio source is a synthesizer, you can press the 'play note' button above the app icon to hear a series of notes so you can hear how loud it is without having to switch and trigger it first. If your audio source has a 'play' trigger for the Audiobus Connection Panel, you can trigger that in the Mixer as well.

Muting or enabling solo for one track changes the color the border of the apps affected by it to blue or yellow. This change is consistent throughout the mixer, audio, and MIDI pages.


The Connection Panel

The Connection Panel provides fast app switching and remote controls for all connected Audiobus apps. It appears in Audiobus and within each connected app that's connected to Audiobus.

In Audiobus 3, you can find it at the top of the audio, midi and mixer page. The Connection Panel is not visible in Audiobus 3 on iPhone when in landscape orientation.

In connected apps the connection panel can be found on the side of the screen. If the Connection Panel interferes with an app's interface, you can hide it temporarily.

Drag off screen or tap to hide
Tap to open app controls
Tap to fast-switch app
App remote controls

Each app can define remote controls that perform some app-specific function, like toggling recording or playback, or switching app mode. These remote controls, as well as the fast switch button, can be accessed by tapping the app icon.

All filter apps show an on-off button to toggle bypass. This is not available for effect Audio Unit Extensions.

To hide the Connection Panel, either tap the hide chevron, or grab the handle and pull it off the screen. You can bring it back at any time by dragging your finger in from the outside of the screen in the same location, then pulling out the tab that appears.

The items exposed by tapping the Audiobus icon in the Connection Panel include a control to fast-switch to the Audiobus app, and controls to create and update presets from the current connection graph, as described in the following section.


Audio Unit Extensions

Audio Unit Extensions are a new audio standard that has been introduced by Apple. They are different from generic music apps in that they can be launched multiple times. This is very useful when trying to create multi-timbral instruments with the same synth app or when using the same filter multiple times in multiple audio pipelines.

Audio Unit Extensions support state saving by default, so their state will always be saved in Audiobus presets.

Since Audio Unit Extensions run inside of Audiobus 3 and will be shut down once Audiobus 3 is quit. They do not appear in the iOS multitasking menu.

When an Audio Unit Extension is added to a slot for the first time, a new instance is created. Every new instance gets a new name and is able to be switched to in the Connection Panel in Audiobus. Audio Unit Extensions do not show up in the connection panel of apps that have not yet been optimized for Audiobus 3.


Presets and State Saving

Presets allow you to save Audiobus configurations and recall them later without needing to manually re-create the connection graph.

In addition to the connections between apps, presets also allow you to save per-app state for apps that support this feature. Recalling the preset will configure each app to the state it was in when the preset was saved.

Apps that support state saving can be found in the compatible apps directory, which is accessible by tapping on 'APPS' in the top left corner of the main screen and selecting the MIDI category. All Audio Unit Extensions support state saving per default.

To create a preset while in Audiobus, open the preset panel by tapping on the 'Presets' button in the top right corner of the screen.

Then tap 'New Preset'.

From within any app currently connected to Audiobus, the same can be accomplished by tapping the 'Add Preset' button from the Connection Panel:

Once a preset has been saved or recalled, you can update it via the 'Update Preset' button in the Connection Panel:

...or via the preset panel within Audiobus:

To delete a preset while in Audiobus, swipe left on a preset and tap the trash can button.

Presets can also be imported or exported via iTunes File sharing.


Hardware Buffer Size

Audiobus supports changing the audio session's hardware buffer size, also known as device latency. Smaller buffer size means faster response time but also higher CPU load.

To access the preferences pane, tap the 'Settings' button at the top of of the screen. Then tap on 'Latency Control'.

Important: If you’re experiencing stuttering audio, please choose the 512 or 1024 frames option.

To find out more, please see this article about hardware buffer size on our blog.

Please always be sure to close all other audio apps first before launching Audiobus.The easiest and quickest way to make sure of that is to reboot your device before a music making session.


Advanced topics

Audiobus Ports

Some apps and multi-channel audio interfaces provide more than one port, letting you choose from a number of inputs, filters or outputs within the app. These are marked by a blue disclosure indicator that can be pressed to select the ports.

Audiobus and Multitasking

Audiobus-compatible apps automatically remain active in the background while an Audiobus session is active.

Apps may mute when disconnected from Audiobus, but will continue to remain active so that they can be reconnected again later with no interruption. The same is true of the Audiobus app itself.

The Audiobus session will continue until all connections are removed, either by ejecting all apps or by swiping all connection pipelines away. Once there are no active connections, pressing the Home button will cause Audiobus to shut down. In turn, all connected apps will also shut down.

Exception: Apps opened up and closed again after previously having been disconnected from Audiobus may suspend, depending on their settings.

When you have finished your session, you can quit each app via the iOS multitasking menu, which is accessed by double-tapping the Home button from the Home screen. Swipe the app that you want to close upwards off the screen to close it.

Important: Some apps might not be visible in the multitasking menu, because they have been launched into the background. The easiest way to make sure they're not running anymore after you're done with your Audiobus session it is advised to reboot your device. That way all apps running in the background get shut down and you won't have to spend time switching to them so they appear in the multitasking menu of iOS and then swiping them out of it.

See this knowledge base article for more information.

Not advanced enough for you?

Show off your Audiobus street cred: Grab your Audiobus merch here!



Audiobus 3 Introduction

Audiobus 3 MIDI

Looping guitar with JamUp in Loopy HD

Recording SoundPrism PRO, Sunrizer and Funkbox in MultiTrack DAW

Filtering FunkBox and Sunrizer with NLog into Loopy HD


Frequently Asked Questions

How do I get rid of the red "(Recording)" bar across the top of the screen?

Or, how to close apps:

  1. Double-tap the Home button.
  2. Swipe left or right until you have located the app you wish to close.
  3. Swipe the app's preview up to close it.

From: Apple Support KB HT5137


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