Installation and Registration
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Choosing your connections
Each Metric Halo 3d device provides two ways for you to physically connect your computer to the audio
I/Os.
• USB
• MHLink (Gigabit Ethernet)
Please note
that both the USB and MHLink ports are configured and controlled via the MIOConsole3d
application on your host computer. Care should be taken that only one instance of the MIOConsole3d
application is visible to your 3d boxes at a time, regardless of how you are connected. This will guard
against any conflicts that may occur due to two MIOConsole instances attempting to control the boxes
at the same time.
The USB Class Audio connection
USB is everywhere... Pretty much any gadget smart enough to have an updatable operating system has
the potential to host a USB audio connection. So for compatibility, USB connectivity is massive.
Compatibility is the raison d'être of the USB port on your 3d boxes.
That said, USB is not an optimal port for audio transport. Many USB chipsets are built with tiny I/O memory
buffers - a signature of a system designed for small asynchronous information transmission, such as a
keyboard, mouse or secondary storage media. Anyone with a DAW knows that tiny buffers are not the
friend of stable audio transfer - they are built for speed, and speed alone. This ‘tiny buffer‘ issue also
evidently applies to newer USB 3.x chips well.
Additionally, USB as a data transport protocol has no concept of real-time clock (something essential
for audio), limited support for time-sensitive sustained data throughput (such as audio streams), and is a
low-priority peripheral port in the resource allocation hierarchy of modern motherboards and operating
systems. Even among systems that are verified to have implemented the USB UAC2 driver, performance
is wildly variable between OS dot-revisions, BIOSes and hardware.
This is why most products which use USB for audio transport write custom software drivers, even if they are
only passing stereo audio. These software drivers rely on a combination of pre-loading audio and larger
buffers, providing protection to the audio stream at the cost of of extra transfer latency, the inevitable
need to code versions for each operating system, and requiring a driver update every time the operating
systems make internal changes.
Metric Halo has incorporated a custom firmware implementation of the UAC2 class audio transport within
the 3d hardware as an alternative to software drivers. Providing an optimized ‘tiny buffer’ transfer mode
in the 3d USB hardware has the advantage not only of lower latency, but far greater stability and cross-
platform compatibility than a software driver solution.
3d USB port Compatibility
macOS version 10.10.x and later, and iOS devices version 11 and later perform consistently well over USB
connections. iOS devices require USB-C or Lightning Camera adapters that support iOS USB Host mode.
Microsoft Windows 10 (starting with release 1073) includes the UAC2 class audio driver as a WASAPI audio
device.
UAC2 driver code for the Linux kernel has been available since around 2015, and versions of Linux which
incorporate this driver should register 3d boxes as ALSA audio devices.
USB Host mode for Android has been available since Android 3.1, via USB OTG (On-The-Go) adapter
cables.
