Download Navigation
Home | Support | Tech Notes | Tech Tips | MOTU AVB | To / From Computer Audio Streams
Document Actions

Tech Tips | MOTU AVB | To / From Computer Audio Streams

View More MOTU AVB Tips »

For more Tech Tips...

To Computer / From Computer Audio Streams

MOTU AVB audio interfaces provide powerful mixing and routing options to meet a variety of audio scenarios. The Routing matrix found in the Routing Tab of the MOTU AVB Discovery App allows you to route signal to and from all of the available inputs and outputs on your interface.

Along with the physical inputs and outputs on the device itself, the built-in 48-channel on-board digital mixer, and any enabled banks of AVB audio streams, the To Computer and From Computer audio streams are important I/O options to be familiar with, as they are required for sending signal to or from your computer.

The Audio Interface device preset provides a default setting to send audio to and from your computer, however for further control, a deeper understanding of the relationship between these audio streams and your computer is necessary.

Before doing any routing, if you intend to send audio to a recording application (like Digital Performer or any other DAW), OR intend to play audio back from your computer in any way (even through applications as simple as iTunes, Quicktime, or when streaming content from the internet), you need to enable To Computer and/or From Computer audio streams. In the Device Tab of the MOTU AVB Web App, scroll down to the Computer Setup section, and set the desired number of To Computer and From Computer audio streams.

Here are a few considerations for deciding how many audio streams are necessary:

  • If you are simply playing audio through any application on your computer, other than your DAW, you likely only need two From Computer streams enabled for stereo playback.

  • Via USB Connection* Via ThunderBolt Connection

  • A larger number of From Computer audio streams are necessary when working in your DAW, and you intend for the ability to route tracks in your project to multiple destinations, (more than one stereo stream).

  • Enabled To Computer audio streams should at least equal the number of individual audio tracks you would like to record at once in your DAW, (stereo tracks equal 2 streams).

  • Generally, there is no issue with enabling more streams than necessary, however this could contribute to high DSP usage if other features on your AVB interface are simultaneously in use.

Note: As of the firmware version v1.2.0, all AVB models have three USB Modes. You can enable 24 channels (in and out) at sample rates 44.1 - 192 kHz, 32 channel at sample rates 44.1 - 96 kHz, or 64 channels at sample rates 44.1 - 48 kHz. You can define which USB Mode the interface is running in from the Configuration Section of the Device Tab. Be sure to download the latest firmware for your unit, which you can find here.

When connecting your AVB interface via ThunderBolt, you can access to up to 128 channels in and out.

Once audio streams are enabled in the Computer Setup section, swing over to the Routing Tab of the MOTU AVB Discovery App. You will now find a "From Computer" bank of inputs listed across the top of the routing grid, and a "To Computer" bank of outputs listed on the left; (USB) or (TB) will be added to its title to specify the connection method being used between your interface and the computer.

In most examples, you will generally only use the "From Computer 1-2" audio streams. This stereo pair will carry the audio coming from your computer (if your AVB interface is set as the primary device for system's sound playback), or if you have designated the AVB interface as the device for your DAW's session.

Expand the From Computer input bank to see each From Computer audio stream, and make a connection between the From Computer 1-2 audio streams, and the physical output channels you want to monitor playback through. (It is generally easiest to expand the output bank on the left side as well, so you can see the individual output channels.) For example, click on the intersection between From Computer 1 and Main Out L, as well as the intersection between From Computer 2 and Main Out R to route your computer's playback to the Main Outs, as shown below.

Once done, when playing audio through iTunes for example, you will see signal activity on the From Computer 1-2 indicator lights and matching signal on the Main Out 1-2's indicator lights.

Often, you may want the same stereo signal to be sent to multiple outputs at the same time. To quickly achieve this, patch the same From Computer 1-2 audio streams to another pair of physical outputs such as the two sets of Phones and the Monitor outputs on the 1248. This stereo signal can also be sent to the Mix In channels (not shown) to feed the interface's on-board mixer for further processing.

If you are working with a larger number of From Computer audio streams (perhaps to route multiple tracks in your DAW to different physical outputs on your interface), the same theory applies. Each From Computer audio stream can be routed directly to its own physical output.

For example, if you own a 1248, and want to process audio from your DAW through a hardware signal processor, each track in your DAW can be routed to its own From Computer audio stream. Then in the MOTU AVB Web App, route each From Computer audio stream directly to one of the 1248's Analog Outputs as shown below.

Configuring the "To Computer" audio streams is done in a similar manner and is required for your computer to "see" any input from your device.

MOTU AVB Theory: When you plug a source into a physical input on your interface, this input is not automatically detected by your DAW or other computer application. This is because your AVB interface can take that input signal and send it anywhere else (on-board mixer, AVB streams, etc.) without the computer ever accessing it. The computer is a specific destination where signal can be sent to, and sending signal to the computer needs to be manually configured. This is why "To Computer" audio streams are considered outputs.

Expand the "To Computer" bank on the left, and the bank of physical inputs on your unit you want to record. Click on the intersection between Analog 1 and To Computer 1, Analog 2 and To Computer 2, etc. Now each input is being routed to its own virtual "To Computer" audio stream, which you can assign as the input to an audio track in your DAW.

Keep in mind, the same input, (Analog 1, for example), can be sent to multiple "To Computer" audio streams for simultaneous recording on multiple tracks. However, each "To Computer" audio stream can only receive signal from one input.

To explain this visually, this means you can make vertical lines in the Routing grid when routing inputs to the "To Computer" streams, but you cannot make horizontal lines.

To check your signal flow when a connection is made, any signal identified by your input channel's indicator lights will also be visible on the "To Computer" stream's light on the left.

Want to see your tip as a MOTU Tech Tip? Is there a feature, technique, or configuration you would like to learn more about? Send us your tips, or topic suggestions »