USB-C Cables and AV (and Why Your Computer Screen Isn't Sharing)

While commercial AV is often the last to adopt new cable standards (it was not long ago we were still installing a lot of VGA cables), lately more and more devices are standardizing around the USB-C connector for data, audio, and video. However, this has lead to a lot of confusion for some of our clients—USB-C is widely marketed as the universal connector, but different specifications for cables and ports can make connecting peripherals more confusing than it needs to be. Different USB-C cables and ports support varying speeds, power delivery capabilities, and even display connections, making it essential to understand what your device and cable can handle. Below, we’ll break down the evolution of USB-C and help you determine which specifications apply to your devices.

USB-C Basics: A 24-Connection Powerhouse

The USB-C connector is designed with 24 contact points, providing a versatile connection capable of supporting data, power, and even video. However, not all of these pins are active in every device or cable. The specific pins used depend on the USB generation, and different generations have distinct capabilities.

The Evolution of the USB Protocol

Let’s start with the basics and work up to the more complex protocols.

USB 2.0: The Foundation of USB-C

USB 2.0, introduced in 2000, supports basic data transfers at a speed of up to 480 Mbps. This is the base specification that USB-C cables support. If your USB-C device is limited to USB 2.0, it’s compatible with all USB-C cables, but the data speed will max out at 480 Mbps. Fortunately, USB-C cables with USB 2.0 support can be quite long—up to 15 feet—without any noticeable data loss due to voltage drop.

USB 3.0 and USB 3.1: The Rise of SuperSpeed

USB 3.0, launched in 2008, brought significant improvements, allowing data transfers up to 5 Gbps—ten times faster than USB 2.0. A notable visual cue for USB 3.0 is the blue color often used for the port, though this isn’t universal.

In 2013, USB 3.1 was introduced, adding more complexity. USB 3.1 has two “Generations”:

  • USB 3.1 Gen 1: This is effectively identical to USB 3.0, with data transfer speeds of up to 5 Gbps.

  • USB 3.1 Gen 2: Gen 2 changes the data encoding, allowing for up to 10 Gbps.

The USB-C pinout diagram. TX/RX1 and TX/RX2 provide additional paths for data, allowing USB 3.2 cables to transmit and receive data faster.

USB 3.2: Complexity Multiplied

With the debut of the USB 3.2 specification, the USB Consortium wanted to unify the USB naming convention. USB 3.2 introduces four modes—1x1, 1x2, 2x1, and 2x2, some of which are functionally the same as previous versions of the USB 3 protocol:

  • USB 3.2 1x1 and 2x1: These use the older USB 3.1 Gen 1 encoding with one or two data pairs, offering speeds up to 5 Gbps.

  • USB 3.2 1x2 and 2x2: These employ USB 3.1 Gen 2 encoding, doubling the speed potential up to 20 Gbps.

In general, the USB 3.2 specification is backwards-compatible, meaning a device with USB 3.2 capabilities can connect with any previous version of USB. However, to achieve maximum data rates with USB 3.2, cable lengths are limited to around 2.5 feet (76 cm).


USB-C Alt Mode: Extending Beyond USB

One of USB-C’s most useful features is Alt Mode, which allows for non-USB data protocols like DisplayPort, HDMI, and Thunderbolt to transmit over the USB-C connection. Here’s how it breaks down:

  • DisplayPort Alt Mode: Allows your USB-C connection to function as a DisplayPort, supporting resolutions up to 4K and beyond, often denoted by a “DP” symbol.

  • HDMI Alt Mode: Rare but available, allowing HDMI to run over USB-C.

  • Thunderbolt 3 and 4: With compatible devices and cables, Thunderbolt enables data rates of up to 40 Gbps and supports displays, making it popular for high-performance tasks.

USB-C for AV: How We Use It

We primarily use USB-C in our installations for bring your own meeting (BYOM) video conferencing systems. There are two main ways this connection works:

  • USB Data Connection: For BYOM systems like the Barco Clickshare, data gets transferred over the usual USB protocol. These systems require a driver to be installed in order for the display to be shared , to convert the video signal to a form that can be transferred over a normal USB data connection.

  • DisplayPort Alt Mode: Some screensharing devices, like the Crestron AirMedia Connect Adapter, use a direct video connection over USB-C. These systems don’t require any additional software to be installed, making them perfect for shared workplaces or workplaces that often have presenters from outside their organization.

How to Identify Your USB-C Specifications

Given the mix of specifications, it can be tough to know what a device’s USB-C port or cable can actually do. Here’s how to decode it:

  1. Check Device Specifications: The manufacturer’s specs are the most reliable source for identifying the USB-C version and features.

  2. Look for Markings:

    • USB Version: USB 3.0 and higher may have a blue-colored port or include an “SS” (SuperSpeed) logo. However, these markings aren’t always consistent across devices.

    • Data Speed Markings: You might see “5,” “10,” or “20” next to the “SS” logo, representing data rates of 5, 10, or 20 Gbps.

    • DisplayPort: Ports with DisplayPort Alt Mode support are marked with a “DP” logo.

USB-C Frequently Asked Questions

  • Physically, yes, but performance will vary. For instance, a USB-C cable for USB 2.0 (commonly called a charger cable on sites like Amazon) won’t support the high speeds of USB 3.2 or Thunderbolt.

  • High-speed data transmission (especially USB 3.2 2x2 or Thunderbolt) is sensitive to cable length and quality. For these, a cable under 3 feet is recommended.

  • Alt Mode allows non-USB signals (like DisplayPort or HDMI) to transmit over a USB-C port, letting one connector handle multiple types of connections.

  • USB 3.2 uses multiple data pairs and encoding schemes to support faster speeds, which means different versions exist under the same name to signal different capabilities.

  • Look for a “DP” logo or check your device's specs. Not all USB-C ports support video output—this depends on whether the port includes Alt Mode for DisplayPort or HDMI.

Understanding USB-C’s variations is essential to make the most of your devices, whether you need high-speed data, video output, or reliable charging. As USB standards continue to evolve, keeping track of these specs ensures compatibility and maximizes performance across all your tech devices. Keeping maximum USB cable lengths, speeds and features in mind when designing your workspace and troubleshooting any connectivity issues can help your team spend less time worrying about technology and more time on the things that matter.

Looking for help with connectivity in your spaces? Whether its full video conferencing systems, hot-desking solutions or classroom displays and audio systems, we can help. Get in touch today.

Evolution AV