Connect your music apps
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Audiobus is a music app that makes your other music apps...better. And it works with a thriving ecosystem of thousands of great music apps and Audio Units.
Audiobus is like a set of virtual cables: you can plug one app into another, into another. With Audiobus you can, for example, take that great synth app or guitar amp app (or vuvuzela simulator. Hey, no judgement here.) and run it into your favourite live-looper or sampler, or a recorder like GarageBand.
And you can add some crunchy distortion or reverb along the way, with support for a huge host of great effect apps and Audio Units: chain them together to perfect your sound.
Audiobus works great with MIDI, too: drive your favourite synth from a sequencer or an arpeggiator, or from an external MIDI keyboard, with a scale quantizer added into the mix to keep you in tune, or add a MIDI based delay effect.
And with the Audiobus MIDI Learn in-app purchase, you can control everything from mixer levels through to preset loading and Audio Unit parameters from your external MIDI gear – or, another app.
Here are some things you can do with Audiobus:
When you start Audiobus, you'll see three empty boxes with symbols in the middle. They are labelled INPUT, EFFECT and OUTPUT. Together, they make up a pipeline: the basic building block in Audiobus.
Audio or MIDI flows from the left to the right, and you can have as many items in the left (input) and center (effect) slots as you like.
Tap one of the buttons to open a list of things that can go into that position:
Some apps can appear in multiple positions – for example, a live-looper app can both send audio (i.e. in the input position), and receive audio (in the output position). See the Audiobus Compatible Apps Directory for an extensive database of compatible apps and where they can be used with Audiobus.
There are several categories of things that can be used, accessed by tabs running along the bottom of the pop-up:
Some items have extended features, which can be accessed by tapping the button beside them.
You can select more than one input at a time, and these will be mixed together for the next stage in the pipeline. You can also have more than one effect: the audio will be passed from one to the next in the chain. You can reorder effects at any time by tapping and holding, then dragging into position.
Once you have selected an app or an Audio Unit, it will load and appear in the slot you tapped. It's now running and ready to send, manipulate or receive audio. Tap it any time to see its interface.
Some apps may require you to tap to launch them manually. You will be prompted to do so, and then returned back to Audiobus.
To remove things from the current session, tap the icon beside them.
Ejected apps should suspend in the background, and thus no longer consume resources on your device. However, many apps do not respond correctly when removed from an Audiobus or Inter-App Audio session, and may continue to remain silently active in the background.
Audiobus will detect this condition and automatically quit these apps. In the event this fails, these apps will reappear in the Audiobus Connection Panel at the top of the screen. You can then switch to the app by tapping and quit it manually.
Every now and then, apps can fail: It sucks, but it can happen. When Audiobus detects an error condition, it will display the app icon in black-and-white, and will attempt an automatic recovery procedure. If the error persists, Audiobus will prompt you to tap to restart the app. If this doesn't resolve the problem, feel free to get in touch.
Once you have a running pipeline, an active connection is indicated by flashing chevrons running between the slots.
On devices with enough space (iPad, or iPhone in landscape mode), a CPU meter appears on the top right of the screen. This provides an estimation of the amount of device resources being used for audio processing. As the indicator approaches 100%, the risk of audio drop-outs and audible crackles increases, so it is recommended to keep an eye on this number.
If you find yourself running out of CPU resources, you can increase the hardware buffer duration (see Settings for details), which gives your device more time to process audio, at the cost of increased latency.
You'll see three different tabs along the edge of the screen: AUDIO, MIDI and MIXER. These control different features within Audiobus.
This is the default screen in Audiobus, and controls all of the audio routing: that is, things that actually do stuff with sound. It's here you add synths, guitar sims, drum machines, delays, EQs, autotuners, live-loopers and samplers, and it's here you select physical audio inputs and outputs.
Apps are full-sized applications you have installed which launch into the background and keep running during your Audiobus session. When you select an app in Audiobus, it will take a moment to load in the background; a loaded and ready status is indicated by a full-color icon.
You may run one instance of an app at a time, although an app may provide multiple ports of different kinds (accessed via the button in the selector) which can be used simultaneously. A live-looper like Loopy, for example, may be used in the output slot in order to receive audio, and simultaneously appear in the input slot for further audio processing at its output. It may also provide individual outputs for each track, so you can apply different effect chains to each, or use a multi-track recorder to record each track separately.
Apps that appear in the output position within Audiobus can be used in the output of more than one pipeline. If the app supports it, this will be sent to the receiving app as separate, independent streams which can be handled individually, such as in a multi-track recorder. Otherwise, the multiple streams will be automatically mixed together into a single stereo stream. In both cases, the levels and balance of the sources can be adjusted via the Mixer.
Tap the app icon to switch to the app once it is loaded.
Occasionally, usually due to a bug in the underlying iOS system, an app will fail to connect. When this error condition is detected, Audiobus will go into recovery mode and attempt to automatically quit and relaunch the app. When this completes successfully, the loaded and ready app will be shown in full-color.
Audio Units are smaller, modular parts of apps you have installed which load directly within Audiobus. You can use multiple instances of the same Audio Unit at once.
Audio Units' interfaces are displayed within Audiobus itself; tap the Audio Unit icon to access its interface. See Audio Units for more information.
Audiobus supports input and output via the built-in microphone and speaker, a headset, Bluetooth devices and class-compliant audio interfaces connected via a USB-to-Lightning adapter. These inputs and outputs can be found beneath the "System" tab in the selector.
For attached devices that support multiple input and output channels, these can be selected by tapping the disclosure buttons. Audiobus supports both mono and stereo combinations of channels, and will automatically convert mono to stereo, and vice versa.
For compatible inputs, the hardware input gain can be adjusted from within Audiobus' Settings.
If you have compatible hardware and have enabled Multiroute Audio in Audiobus' Settings, you can simultaneously receive and send audio with an audio device plugged into the headphone port, and a USB audio interface connected via the Lightning port. This can provide for separate monitor and house signals, for instance. Note that due to an iOS limitation, Bluetooth audio devices and AirPlay are not supported when this mode is enabled.
If you experience unexpectedly silent audio output, try disabling Multiroute Audio mode, as this can occasionally interfere with normal operation.
On some devices, for reasons unknown, audio input via the built-in and headset microphone is processed by the iOS audio system through a highpass filter, knocking out the lower frequencies. You may find enabling Measurement Mode improves bass response with your device. Your mileage may vary.
Upon selecting an input, Audiobus will typically auto-select the default output device. However, when using microphone input Audiobus won't automatically select the speaker output: you will need to select the output, and Audiobus may warn you about feedback.
Note that if you're using external hardware, it's up to you to watch out for feedback, just like with physical audio equipment.
Audiobus will always use the default sample rate of the connected device. Internally, Audiobus uses 32-bit floating-point audio for maximum fidelity and mixing headroom.
Audiobus' MIDI screen allows you to control the flow of MIDI – that is, note information which is used by synthesizers to produce sound.
Items in the input slot produce MIDI – this includes external MIDI equipment, MIDI sequencer apps and Audio Units, and audio-to-MIDI utilities, for example. Things in the effect slot manipulate MIDI, like scalers, quantizers or arpeggiators. Things in the output slot receive MIDI, like synthesizers and other virtual instruments.
Many apps and Audio Units are used on the Audio and the MIDI screens at the same time. For example, a synthesizer which receives MIDI and generates audio, or an audio-to-MIDI utility which generates MIDI notes in response to incoming audio.
Audiobus defines its own MIDI standard which avoids the various usability issues of the built-in MIDI system on iOS, and allows the seamless connection of MIDI senders, effects and receivers from within Audiobus.
Upon selection, apps will take a moment to load; a loaded and ready status is indicated by a full-color icon.
Occasionally, due to a bug in the underlying iOS system, an app will fail to connect. When this error condition is detected, Audiobus will go into recovery mode and attempt to automatically quit and relaunch the app. When this completes successfully, the loaded and ready app will be shown in full-color.
Not all apps that are capable of MIDI support Audiobus' MIDI standard. These can still be used via Audiobus' Virtual MIDI features; see below for details.
Audiobus also supports Audio Unit MIDI; see the list of installed Audio Units that support sending or processing MIDI on the "Audio Units" tab on the selector.
You can run more than one instance of the same Audio Unit. Instances operate entirely independently of each other.
Both Audiobus MIDI and the Audio Unit MIDI standards replace the old notion of MIDI channels with more clearly defined ports, which when available, are accessible via the button in the selector. You can still select MIDI ports for MIDI hardware and Virtual MIDI ports.
MIDI hardware which is connected via a USB-to-Lightning adapter or via Bluetooth appears within the "System" tab.
Select specific MIDI channels to receive from, or send to, by tapping the button. By default, Audiobus will receive from all channels, and will pass through the MIDI channel of messages unmodified. By selecting a specific MIDI channel, Audiobus will filter out any messages not on that channel, and will remap outgoing messages to that channel.
Connect to Bluetooth MIDI hardware by tapping "Bluetooth Connections". Upon connection, this hardware will appear within the "MIDI Devices" list.
You can also facilitate incoming Bluetooth connections by tapping "Bluetooth Advertising". When you enable advertisement by enabling the "Advertise MIDI Service" switch beneath this item, other devices will be able to see and connect to your device.
Other computers and devices that support Network MIDI, including other iPads or iPhones running Audiobus, appear within the "System" tab.
Note that due to the limitations of the underlying Core MIDI standard provided by iOS, network MIDI devices all use the same internal MIDI endpoint (sometimes seen in other apps as "Network Session 1"), and it is impossible to target just one device for sending or receiving MIDI. This means that if you have selected more than one network MIDI device in the input position, incoming messages will appear to come from all network MIDI sources at once. Similarly, with more than one network MIDI device in the output position, messages will be sent to all network MIDI devices at once.
To work around this limitation, use MIDI Channels to differentiate devices, accessible via the button in the selector. By default, Audiobus will receive from all channels, and will pass through the MIDI channel of messages unmodified. By selecting a specific MIDI channel, Audiobus will filter out any messages not on that channel, and will remap outgoing messages to that channel.
Apps which do not support the Audiobus MIDI or Audio Unit MIDI standards, but still work with basic Core MIDI, can still be accessed via the "Virtual MIDI" section within the "System" tab when they are running. Apps which publish a Virtual MIDI port appear within this list. Audiobus also provides its own Virtual MIDI Bridge port, which will appear as a MIDI source or destination (named "Audiobus 3") within apps that use Core MIDI only.
Core MIDI setup can be confusing as there are frequently multiple, mutually-exclusive ways to connect two apps, and how setup is performed varies between apps. It is always preferable to use Audiobus MIDI or Audio Unit MIDI where available.
Connections can often be made from either side of a connection: by selecting the source app from within Audiobus' Virtual MIDI list, or by choosing "Audiobus 3" as a destination from within the source app. When doing the latter, you must select "Virtual MIDI Bridge" within Audiobus instead of selecting the port named after the source app.
Care must be taken when working with such apps and other MIDI sources, as they may perform their own automatic MIDI routing in the background, which can have unpredictable results. If you are experiencing unexpected results like doubled notes, ensure MIDI inputs are disabled within the settings of the app in question.
Select specific MIDI channels to receive from, or send to, by tapping the button. By default, Audiobus will receive from all channels, and will pass through the MIDI channel of messages unmodified. By selecting a specific MIDI channel, Audiobus will filter out any messages not on that channel, and will remap outgoing messages to that channel.
Also appearing within the "System" tab for the output slot is the MIDI Learn port, used for controlling other aspects of the Audiobus session from incoming MIDI messages. See MIDI Learn for details on this feature.
Audiobus also supports MIDI clock receiving and sending, which is configured from Audiobus' Settings. See Synchronization for details.
The Audiobus mixer provides controls to adjust the levels and balance of all audio and MIDI sources and effects.
Every feature of Audiobus' mixer can be controlled by an external MIDI controller or other MIDI source such as an LFO generator or sequencer, using the Audiobus MIDI Learn In-App Purchase. See MIDI Learn for details.
The Audiobus Connection Panel appears at the top of the screen in Audiobus on devices with enough room (iPad, or iPhone in landscape mode), and provides access to a range of controls for each app and Audio Unit in use.
Apps can provide their own buttons to perform tasks specific to the app in question, and there are a number of common buttons:
Tap an app icon to expand or contract the controls for that app/Audio Unit. | |
Switch to an app, or open the interface for an Audio Unit. | |
ON OFF | Toggle bypass for effect apps and Audio Units, switching between modified and original audio. |
Toggle transport play/pause for the app. | |
Toggle recording. |
The Connection Panel also appears within each app used with Audiobus, and works as a remote control for the other apps in the session, as well as a means to switch between apps.
This panel can be hidden if necessary by tapping the or button, or tapping and swiping from this button. Bring the panel back by swiping back in from off the screen, then tapping and dragging the small handle that appears.
Hiding and showing the Connection PanelEvery element on the Audiobus Connection Panel can be controlled by an external MIDI controller such as a foot switch, using the Audiobus MIDI Learn In-App Purchase. See MIDI Learn for details.
The Audiobus toolbar provides access to transport play and pause, tempo controls, and other features:
Toggle play and pause. | |
120 | Adjust the current tempo using a number pad, or tap out a tempo. |
Open the app's settings. See Settings. | |
Open MIDI Learn configuration. See MIDI Learn | |
Open Audiobus Remote if it is installed on your device. See Audiobus Remote for details. | |
Start a new session. This will reset the session to a blank state. | |
Open the Presets selector. Audiobus' presets feature allows you to save the state of an Audiobus session, and the state of every app and Audio Unit within it. See Presets for more information. |
Audiobus supports session saving with presets. When you load a preset, the entire session is recalled, along with the saved state of each component.
To access the presets panel, tap the icon on the toolbar.
Tap "New Preset" to create a preset from your current session. Audiobus will generate a name automatically, and the new preset will appear in the list.
You can also create a new preset from the Connection Panel by tapping the Audiobus icon to open its controls and tapping . The same control exists on the Audio Unit screens.
Tap a preset in the list to display the available actions:
To delete a preset, swipe left and tap the Delete button.
Presets can also be imported or exported via iTunes File sharing (using older iTunes versions, or an app like iExplorer or iFunbox).
iOS Files/iCloud support is coming to Audiobus soon, along with folder management and enhanced preset export.
Tap to search for presets. Tap Name and Date under "Order By" to change the sorting of the list.
Presets can be loaded using a MIDI controller such as a foot switch, using Audiobus MIDI Learn. See MIDI Learn for details.
An exclusive feature of the Audiobus platform is Audiobus State Saving. This provides apps the ability to save and restore their configuration within Audiobus presets.
When an Audiobus preset is loaded, the saved state within is sent to participating apps, which restore the configuration.
See a list of apps which support Audiobus State Saving on the Compatible Apps Directory.
You may disable Audiobus State Saving from the Audiobus category beneath the System Settings app. See Advanced Settings for details.
Audio Units automatically support saving and restoring of state, which Audiobus also supports, along with Audio Unit factory presets and Audio Unit user presets (see Audio Unit Factory and User Presets for details).
Audiobus presets can be added together, providing for presets to be used like a library of commonly-used components.
Tap Add beside a preset to add its contents to the current session. The pipelines saved within the selected preset will be added to the current session's configuration.
Any Audio Units used within the added preset will have new instances created, so the new pipelines can be run alongside the ones in the current session seamlessly. Additionally, any MIDI Learn configuration stored within the preset will be imported.
Audiobus supports the Audio Unit standard on iOS. Audio Units are smaller, modular parts of apps you have installed which load directly within Audiobus and other host apps.
After loading an Audio Unit within Audiobus, the user interface for the Audio Unit can be opened by tapping the icon on the main screen, or by tapping beside the Audio Unit's icon on the Audiobus Connection Panel.
The Audio Unit screen will display the interface for the Audio Unit as well as an on-screen keyboard, if the Audio Unit in question supports MIDI input.
The toolbar at the top displays the following:
Toggle play and pause. | |
120 | Adjust the current tempo using a number pad, or tap out a tempo. |
Create or save Audiobus preset | |
Toggle keyboard, when available. When the keyboard is hidden, the Audio Unit view can take up the full screen height, if supported by the Audio Unit. |
On devices with enough room (iPad, and iPhone in landscape), the Connection Panel appears on the right of the toolbar.
Depending on whether the on-screen keyboard is visible, the Audio Unit Preset selector is shown on the top toolbar or the keyboard toolbar, when enough room is available. See Factory and User Presets below for details.
If an Audio Unit supports MIDI input, an on-screen keyboard will be available from within the Audio Unit screen. Depending on the interface preferences determined by the Audio Unit, the keyboard may be shown or hidden by default.
The keyboard provides velocity control by pressing towards the top or bottom of keys, and an adjustable range which can be set by unlocking the keyboard with the button, then swiping or pinching, or by tapping the and buttons.
The following items appear on the toolbar above the keyboard:
HOLD | Toggle hold, which continues holding keys after you release them. Held notes are saved in Audiobus presets and restored upon load. |
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Presets | When sufficient room is available on the toolbar (iPad and iPhone landscape), the presets selector is visible and provides access to factory and user presets. See below for details. |
Move the keyboard up or down an octave. | |
Toggle keyboard lock. When unlocked, the keyboard can be dragged left or right and pinched to change the visible range. | |
Toggle keyboard. When the keyboard is hidden, the Audio Unit view can take up the full screen height, if supported by the Audio Unit. |
Audio Units can provide a set of configurations accessible via the "Presets" selector above the Audiobus keyboard, or on the top toolbar of the Audio Unit screen.
Audio Unit presets differ from Audiobus presets in that they are specific to the individual Audio Unit.
You can create your own Audio Unit presets by tapping the "Save" button at the top of the Audio Unit preset selector; the current state of the Audio Unit will be saved to this preset, and restored upon loading it again.
Audio Unit user presets, as well as factory presets, remain available across Audiobus sessions.
You can load Audio Unit factory and user presets via a MIDI controller using MIDI Learn.
Unlike apps, Audio Units are entirely loaded and run within Audiobus. This means that they can be loaded multiple times, and so you can have more than one instance performing different tasks.
After you have loaded an Audio Unit into your Audiobus session, the next time you select the same Audio Unit from the selector, you will be presented with a "New Instance" item. Selecting this will load a brand new, independent instance of the Audio Unit.
Instances are identified by a letter of the alphabet, and appear alongside each other in the Audiobus Connection panel.
Some Audio Units may provide more than one output. Like apps with similar abilities, Audio Units with multiple outputs are displayed in the selector with a icon. Tapping the Audio Unit reveals the available ports.
Due to limitations in the underlying iOS implementation of this feature, these ports become available only once the Audio Unit in question is loaded. Upon loading, the next time the Audio Unit is shown in the selector, the secondary ports will be visible.
This will change in an upcoming Audiobus release, which will incorporate the ability to remember secondary ports and display them in advance of loading the Audio Unit.
At present, Audiobus supports only additional MIDI outputs, not secondary audio inputs and outputs. Only the first audio input and audio output will be used by Audiobus at this time. This too will change in an upcoming release.
Audiobus MIDI Learn allows you to control every aspect of your Audiobus session, and all apps and Audio Units that are part of it, using MIDI: from a USB or Bluetooth MIDI controller like a foot switch, or from another app or Audio Unit.
With MIDI Learn, you can, for example:
MIDI Learn is a modestly-priced In-App Purchase available from within the Audiobus app.
Configuring MIDI Learn is the process of making bindings between incoming MIDI events, like foot switch presses, dial adjustments or incoming oscillator signals (see Triggers), to actions within your Audiobus session, like muting an app or adjusting an Audio Unit parameter (see Actions). You can bind more than one action to a trigger, in order to create composite actions.
To access MIDI Learn setup, tap the button on the Audiobus toolbar.
The first time you open MIDI Learn setup, you will be presented with a short introduction, and a prompt to buy the In-App Purchase. If you would like to evaluate before purchasing, you can simply close this prompt and continue to explore the setup process; however, actions will not be performed in response to MIDI events until the In-App Purchase is unlocked by tapping the "Buy" button at the top right.
If you have already purchased the feature, you will not be charged a second time; you can also use the "Restore Purchases" button in Settings to unlock the feature.
Open opening MIDI Learn setup, the screen will dim, leaving highlighted the items on screen that you can bind actions to.
Along the top of the screen are a number of controls:
PROFILES | Access and manage profiles (see below). |
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Manage Bluetooth connections. | |
DONE | Leave the MIDI Learn setup screen. |
MIDI Learn configurations are stored within profiles, which are accessed from the "Profiles" button at the top right of the MIDI Learn screen.
Each Audiobus preset has a profile, which loads automatically when you load the preset. Thus, you can have MIDI Learn configurations specific to each preset.
You can also have any number of "Global Profiles" which, once opened, remain active across sessions. This allows you to have configurations that work regardless of what preset is opened.
When configuring MIDI Learn, you can select whether to edit the current preset's profile – labelled "Current Preset" within the Profiles selector – or whether to edit a global profile, under the "Global Profiles" heading. The profile currently being edited is highlighted with a blue background.
The currently-active global profile is displayed with a check mark on the right. This means the bindings configured within this profile are active.
Aside from editing, a number of actions can be performed on the selected profile:
RENAME | Edit the name of the preset. |
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COPY | Duplicate the preset to a new entry. |
SHARE | Export and share the preset. |
Create a new global profile by tapping "New Profile" in the top right of the Profiles selector.
To add your first MIDI Learn binding, tap any of the undimmed user interface elements on the main MIDI Learn setup screen. A pop-over will be displayed with the name of the action. For elements with multiple possible actions, a list of these will appear: Tap the action you wish to create a binding for.
MIDI Learn Action Pop-OverWhen the action pop-over is showing the "Listening for MIDI" text, Audiobus is listening for incoming MIDI signals from any connected device. Once an incoming MIDI message is received, it will be set as the configured trigger.
You can also manually define a trigger by tapping in the bottom area of the action pop-over. You will then be prompted to select a MIDI source, a type of MIDI message and other parameters. See Triggers below for more info on triggers.
Once a trigger has been set, it is shown at the bottom area of the action pop-over. Tap it to edit the trigger, or tap to clear the binding and start over. Once you have cleared a trigger, you can tap "Learn" to go back into listening mode, or "Setup" to manually setup a trigger.
Many actions have additional parameters, which are displayed on this screen. For example, the Mute/Unmute action can be configured to operate in toggle mode, to mute, or to unmute, and the Adjust Parameter action can jump to a pre-set value, or increment or decrement by a pre-set amount. See Actions below for more info on actions.
You can create bindings for multiple actions, so that each configured action is performed at the same time when the trigger occurs. Audiobus will display a summary of any other actions currently bound to the same trigger at the bottom of the action pop-over. Tap this area to view and configure each of the other actions.
You can also create multiple variants of the same action, which can be assigned to different triggers. To create a new action, tap "New" at the top right; a brand new action screen will be displayed, which can be configured independently from the original.
Audiobus provides a special MIDI output which allows one to drive the MIDI Learn system from the output of any app or Audio Unit MIDI source. For instance, one can use an LFO generator Audio Unit to drive the parameter of an effect Audio Unit to create a sweep effect, or use an audio-envelope-to-MIDI Audio Unit to control the gain of an audio source, for a ducker/sidechain compression effect.
To use the Audiobus MIDI Learn Receiver, tap the button for the output slot of a MIDI pipeline, and then from the System tab, select MIDI Learn.
Then tap the large icon in the output slot to enter MIDI Learn setup for that MIDI Learn Receiver.
Configured MIDI bindings for MIDI Learn Receivers are always stored within the Audiobus preset.
Audiobus MIDI Learn actions can be triggered by:
Using the training mode is the easiest way to choose a trigger when creating a new binding: as soon as the action pop-over is displayed, Audiobus is listening for incoming MIDI messages from all possible sources.
If you wish to choose a trigger manually, however, you can tap the bottom area of the action pop-over to display the trigger selector.
Manual Trigger SelectionYou will be prompted for a MIDI source, a message type, and other parameters depending on the kind of message selected, and the kind of action being bound.
You can also use the trigger selection interface to fine-tune your trigger after using the automatic training mode. In particular, you may wish to adjust the trigger action, or the CC range. Tap in the bottom area of the action pop-over to access trigger configuration.
For actions that are momentary in nature, such as muting or unmuting, or toggling play/pause, the following actions are available for MIDI CC and Note messages:
Foot switches and MIDI controller buttons can operate in either toggle mode or momentary mode. In toggle mode, the first press sends a non-zero CC value, and the second press sends a zero value. In momentary mode, the press will send a non-zero CC value, and the release will send a zero value.
Audiobus will detect this and automatically select the "Toggle" action or the "Press" action for bindings, depending on whether the controller is detected in toggle or momentary mode.
For continuous actions, such as Audio Unit parameter adjustments or volume adjustments, you can select the source CC range for the action. This determines the range of incoming CC values that will be mapped to the full range of the action.
To reset the trigger, tap "Clear" at the top right; Audiobus will return to the action pop-over and re-enter training mode.
Audiobus provides actions to control almost every aspect of a session.
Some actions provide adjustment of a continuous parameter, like gain or an Audio Unit parameter. These allow you to define how the adjustment is made:
Other actions will toggle state, such as muting or unmuting an audio source, turning on or off an effect, or toggling play/pause. These actions can operate in one of three modes:
Here is a complete list of the available actions.
Synchronization is used to keep participating apps, Audio Units and external devices in time. Audiobus supports four kinds of clock sync:
Audiobus' synchronization settings can be found within Settings, which can be reached by tapping the icon on Audiobus' main screen, then selecting Sync Settings.
Ableton Link is the recommended sync mechanism, due to its robustness and feature set. In Audiobus, Ableton Link is turned on by default, and – unique to Audiobus – will automatically enable Link in any apps used within an Audiobus session.
Apps connected via Link will all share a common timeline, and can start and stop at any time without affecting other apps – they will start at the next bar, or whatever interval they have selected. This differs from other sync mechanisms, which tend to lock transport (i.e. play/stop) state across participants.
You can also enable Link Start Stop Sync from within the Link settings of each app, including Audiobus, and this will cause transport state changes to be synchronized across apps that also have Start Stop Sync enabled.
Note that by default Audiobus App Start/Stop is also enabled, so if you have enabled Link Start Stop Sync within Audiobus, Audiobus will automatically synchronise transport state with connected apps, even if they do not support Start Stop Sync themselves.
You can set the Quantize Duration on the Sync Settings screen in Audiobus; this duration will determine at what sync intervals Audiobus transport start/stop will occur. For example, if you set it to 4 bars, Audiobus will wait until the shared timeline reaches a 4 bar boundary before starting play.
MIDI Clock Sync is a standard which is very well established throughout the music tech world: most MIDI devices that have transport controls will also support MIDI sync, and many apps also support it.
Audiobus can act as a MIDI clock receiver (a.k.a. "slave"), or a sender ("master"). This is particularly useful for providing sync with external MIDI hardware, or apps that don't support any other sync standard.
Audiobus provides offset adjustments in both receive and send mode, allowing for fine tuning synchronization as needed.
When used in conjunction with Link, Audiobus' MIDI sync feature will act as a bridge between the two systems.
Note that, unlike Ableton Link or Inter-App Audio Sync, MIDI sync can have reliability issues as it is vulnerable to unreliable connections (such as Bluetooth), and other sources of noise. Audiobus has a sophisticated receiver which applies a range of techniques to minimise jitter and maximise accuracy, but in extremely adverse conditions, there may be some sync inaccuracy.
If you are experiencing unreasonably inaccurate incoming clock sync with Audiobus, you can send in a recording of incoming MIDI data for diagnosis: enable Diagnostic Mode, then reproduce the issue. Then tap "Get Support" in Audiobus' in-app settings to send in a log (requires outgoing email setup on your device).
iOS provides a built in mechanism for syncing an app hosted via Inter-App Audio with the host app. Audiobus provides sync via this mechanism by default.
Note that not all apps support syncing via this method.
Audiobus uses the play/pause Connection Panel triggers for apps that provide them to sync the transport state with its own; starting Audiobus' transport will cause any available play/pause triggers to be activated.
If you experience problems with any apps' transport state sync when combining this with other sync methods, try disabling this setting.
To access Audiobus' settings, tap the icon on the main screen. The following settings are available here.
Adjusts the system hardware buffer duration. This allows you to select the amount of audio that is rendered in each processing cycle, which is a trade-off between responsiveness and processing demands.
A small latency, like 64 or 128 frames, provides very fast response with near-inaudible latency, but places a higher demand on the device's processor. A higher latency results in more laggy-sounding audio, but is easier on the processor.
If you find your audio glitching with complex setups, then try increasing the latency.
Audiobus needs to have control over the audio session in order to be able to modify this property. To ensure this, make sure Audiobus is the first audio app you open at the beginning of your session.
Adjusts the hardware sample rate, if available.
Audiobus needs to have control over the audio session in order to be able to modify this property. To ensure this, make sure Audiobus is the first audio app you open at the beginning of your session.
Note that most audio devices only offer support for a limited number of sample rates. If a selected sample rate is not supported by the hardware, it will display an "Unavailable" notice upon selection.
With Multiroute Audio mode you can use an audio device plugged into the headphone port (on iOS devices that still have one) simultaneously with a USB audio interface connected via the Lightning port. This can provide for separate monitor and house signals, for instance.
Note that due to an iOS limitation, Bluetooth audio devices and AirPlay are not supported when this mode is enabled.
Some audio inputs allow you to adjust the input gain levels. When available, this setting provides access to this system-level configuration.
See Synchronization for details.
More advanced, and rarely used, settings are available in the iOS Settings app, under "Audiobus 3":
Sometimes, things can go wrong: yeah, it sucks – but I'm here to help. Oh, hi, by the way - I'm Michael, the developer of Audiobus, and I'm generally pretty reachable and keen to solve any issues that arise.
First, if you're having trouble, there are a couple of common things to try first:
Also, take a look at these known issues:
If none of that solves it for you, there are a number of ways to get help.
If you've got questions about workflow, or third-party apps or hardware, the best place to go is probably the Audiobus Forum. This is a very welcoming and active community of iOS musicians, pros and hobbyists, and you're near certain to get a helpful and friendly reply fast. I hang out there too, as @Michael – just @ me to get my attention.
The forum's also a great place to meet other musicians, share your creations and get feedback, discuss other apps and tech and a bunch of other stuff. Drop by, say hello!
If you're actually experiencing some issues with Audiobus, you can contact me directly via the "Get Support" feature in the app – just tap on the main screen, and then "Get Support", and it'll open a new message window with some diagnostic stuff attached (this does require your device to be able to send outgoing email).
Chances are I may ask you to turn on Diagnostic Mode in order to gather a bit more info about what's happening for you – I'd recommend turning this on, and then reproducing your issue immediately before using "Get Support", to give me the best chance to figure out what's happening straight away.
If Audiobus or another third-party app is crashing, and dumping you back to the home screen, it would be very helpful to see the associated crash log so that I or the developer of the third-party app can fix the issue. While we may get anonymized versions of these in a big lump, it can be difficult to tie certain events to individual crashes, which is necessary for nailing a bug.
If you're up for it, finding and sending me a crash log can go a long way towards solving the crash. Here's how to find and send them in:
In some cases, it can be helpful to see some more diagnostics from your device, and I may ask you to send a sysdiagnose. Sysdiagnose is a built-in iOS utility which records a variety of diagnostic information to a file that can be sent to Apple or to developers.
To provide a sysdiagnose:
Audiobus 3.4 is a release that focuses on improving workflow, and removing constraints.
3.4 brings lots of improvements and new features to the MIDI Learn system introduced in version 3.3. There's the new MIDI Learn Receiver, which sits at the output of any MIDI pipeline. It's great for controlling parameters from the output of audio units and apps, like LFOs and envelope-following audio units like FAC Evolver.
Creating a ducker with MIDI Learn ReceiverYou can now adjust the range for parameter adjustment actions, as well as the range of incoming CC messages, and there are more options for toggle actions like mute/unmute, including the ability to invert the incoming value from a CC. The latter can be useful for pairing up more than one action on the same trigger, like switching between two different effects by bypassing one, and un-bypassing another.
There's a new "Add" button for appending presets to your current session, so you can use presets like reusable components. It's particularly great with Audio Units.
You can now sync external MIDI gear with MIDI Sync: Audiobus works as either MIDI master or slave. It also seamlessly bridges between MIDI Sync and Ableton Link. It's got a configurable offset feature, so you can correct any sync discrepancies that come up. And it works with Virtual MIDI, so you can sync with those apps that don't yet support Link or IAA sync.
Speaking of Virtual MIDI, there's a new Virtual MIDI Bridge input which joins the Virtual MIDI bridge output introduced in the last update. This is great for interacting with apps that support neither IAA nor Audiobus MIDI standards.
Audiobus now does Audio Unit user presets. Audio Unit presets you create can be reused across different Audiobus sessions, and you can switch user presets via MIDI Learn.
There's a brand new selector, with separate tabs for system components, apps, and Audio Units, and with a new Favorites tab.
New selector interfaceMIDI inputs which appear in more than one pipeline are now treated independently, allowing for per-pipeline muting and volume control. This works great with the new MIDI Learn toggle actions, as you can toggle smoothly between synths by muting the input for one MIDI source, and unmuting the other. And to support that use case, when you mute MIDI sources, currently-held nodes will continue to play out until they're released, rather than immediately silencing.
There are lots more little improvements and fixes. Here's the full list:
I hope you enjoy AB 3.4! If you've got any issues, suggestions or other feedback, feel free to open a new thread on the forum, hit "Get Support" in the app, or send an email to [email protected].
Stay tuned – there's more good stuff to come in 3.5.