Marshall VAC-12HUC

1. Introduction

The Marshall VAC-12HUC advanced USB-C (USB3.0/2.0) adapter easily connects video and audio sources to a computer for live streaming, video conferencing, video production, and recording. Its simple plug-and-play design seamlessly integrates professional video sources with PC-based applications. The HDMI 2.0 input supports video formats up to UHD, while an active loop-through output allows the source to be simultaneously fed to monitors or recorders. UVC protocol support enables the host application to control video format, frame rate, and other settings independently of the original source. Setup is straightforward; the VAC-12HUC becomes fully functional within seconds of connection and is powered by the host computer's USB port, eliminating the need for external power adapters.

2. Features

• HDMI 2.0 INPUT with active loop-through OUTPUT (supports formats up to UHD)
• Stereo analog audio INPUT. Activates automatically when an audio source is plugged in.
• USB-C (USB3.0/2.0) computer interface with UVC control and scaling.
• Power provided via USB-C (USB3.0/2.0) from computer or laptop.
• Plug-and-Play. Driver installation is not required for most applications.
• Compatible with popular applications such as Zoom, Skype, OBS Studio, and many more.

3. Package Contents

• (1) VAC-12HUC Unit
• (1) USB 3.0 "A - type" to "C - type" cable
• (2) Mounting brackets with 8 attachment screws

4. System Requirements

• Host computer with a recent operating system, such as Windows 10 or Mac OS X.
• Available USB 3.0 port (supports up to 3840 x 2160p30 to host computer), or
• Available USB 2.0 port (supports up to 1280 x 720p30 to host computer).

5. Connections and Indicators

Input Side:

• 1. HDMI Input
• 2. Analog Stereo Line Input

Output Side:

• 3. USB-C Output to Computer
• 4. HDMI Loop Output

Indicators:

• 5. Power LED - USB Power Connected
• 6. Signal LED - HDMI Video Available

6. Setup and Quick Start

1. Ensure the computer is powered on and operating. Connect the VAC-12HUC to the host computer using the provided USB 3.0 cable. Allow approximately one minute for the computer to identify the unit and set up drivers. The red LED on the Input Side will light up after about 3 seconds.
2. Open an application such as Zoom, Skype, or OBS Studio, and select the Video and Audio devices. The VAC-12HUC adapter will identify itself as "MEI USB3.0 Capture Device". Depending on the application, it may appear as a Camera or a Capture Device.
3. A message indicating "INPUT: NO SYNC" might display until a video source is connected. The output resolution format and frame rate may differ based on the application software.
4. Connect a video source. The green LED on the Input Side will light up, indicating a compatible video source is attached. The on-screen message will update to show the input and output status and will disappear after approximately 8 seconds.

At this point, the VAC-12HUC is operating and ready for use. Control of the device depends on the capabilities of the software being used for conferencing, recording, or streaming.

Note: Most video conferencing applications automatically set the USB output format to 720p. This setting does not affect the HDMI loop-through output, which will retain the original input signal's format.

5. External audio (Optional): If desired, audio can be provided from a source other than the HDMI input. Plug the audio source into the 3.5mm audio jack on the unit. When the plug is fully inserted, the incoming HDMI audio will be muted, and the analog audio will take its place. This analog audio will be present at both the USB output and the HDMI output.

7. Specifications

HDMI Input and Output

• HDMI Conforms to HDMI 2.0 standard.
• HDCP 1.4 and 2.2 compliant.
• Video Frame Rates from 23.98 to 60.00.
• Video Input Formats from 480i/p, 576i/p to 4096x2160p at 30 fps.

USB-C (USB3.0/2.0) Output

• Output is backwards compatible to USB 2.0.
• Actual video format and frame rate are dependent on UVC control commands received from the host computer.
• Connected via USB 3.0, transfers formats up to 3840 x 2160p30 to the host computer.
• Connected via USB 2.0, transfers formats up to 1280 x 720p30 to the host computer.
• When connected to a USB 2.0 port, a 720p or below input video source is recommended.

Audio Input

• Embedded audio from HDMI is passed through to HDMI Out. Channels 1 & 2 are sent to USB.
• External stereo analog line level input via a 3.5mm stereo TRS jack. This input switches on when a plug is inserted, replacing the HDMI audio for both the HDMI Out and USB computer output.

Operating Temperature

• 0~40°C (32~104°F).

Power Rating

• 5V 1A.

8. Block Diagram

VAC-12HUC Functional Block Diagram:

The diagram illustrates the signal flow: HDMI In and Analog Audio Insert feed into the USB Process, which outputs to USB 3.0. The HDMI In signal is also passed through to HDMI Out.

9. Tips and Fixes

USB Device Not Recognized or Unsupported Parameters

Ensure you are using the supplied USB-C cable. If lost or damaged, replace it with a "USB 3.0 type A-to-C" cable that provides adequate power and bandwidth. If the issue persists, try a different cable. A similar message may appear if the VAC-12HUC is connected to a USB 2.0 port. Connect to a USB 3.0 port (often identified by a blue connector interior) to resolve this. If only a USB 2.0 connection is available, lowering the source video format to 720p often resolves issues.

Incoming Video Format Mismatch

The VAC-12HUC uses the USB industry standard UVC control protocol, allowing the host computer to adjust the format and frame rate independently of the incoming source. Many applications offer controls for these parameters. Video conferencing applications may automatically force settings that work best, potentially differing from the source. Consult the application's documentation for details.

Blank Picture on Recorder or "Input: HDCP Content" Message

This issue is typically related to HDCP (High-Bandwidth Digital Content Protection), HDMI's copy protection system. HDCP-protected content is intended for display devices only (monitors, projectors, TVs) and cannot be recorded or transmitted. Consumer devices like DVD players or set-top boxes may enforce HDCP even for non-copyrighted material. Video cameras generally do not use HDCP. Computer HDMI outputs may or may not use HDCP depending on the content. For more information on HDCP, visit www.hdmi.org.

Using VLC Media Player

To ensure correct picture and format in VLC:

1. In VLC, go to the MEDIA tab and select OPEN CAPTURE DEVICE.
2. In the window that appears, select "MEI USB3.0 CAPTURE DEVICE" for both Video Device Name and Audio Device Name. Click on ADVANCED OPTIONS.
3. In the next window, set the Aspect Ratio to 16:9.
4. For Video Input Chroma Format: type YUY2 if connected via USB 3.0, or MJPG if connected via USB 2.0.
5. Click OK to close the window.
6. Click Play. The incoming video and audio should now appear correctly.

Warranty

Marshall warrants the VAC-12HUC HDMI to USB-C Converter to be free from defects in material and workmanship for one year from the date of purchase from an authorized Marshall dealer. Should the product fail within this period, Marshall will, at its option, repair or replace the unit, provided it has not been subjected to accident, disaster, abuse, or unauthorized modifications (including static discharge and power surges). Repairs for units failing under conditions not covered by this warranty will be charged at the current price of parts and labor and are warranted for 90 days from the date of reshipment. Customers are responsible for insuring the unit or assuming the risk of loss or damage during transit. Units will not be accepted without a return authorization number.

This warranty is in lieu of all other warranties, expressed or implied, including any implied warranty of fitness or merchantability for a particular purpose, all of which are expressly disclaimed. Proof of sale may be required for warranty claims. Cables are covered by a 30-day warranty against manufacturing defects.

While the content of this manual has been carefully checked, Marshall assumes no responsibility for any inaccuracies. Marshall will not be liable for direct, indirect, incidental, special, or consequential damages resulting from any defect or omission in this manual, even if advised of the possibility of such damages. Technical information regarding the VAC-12HUC features and specifications is subject to change without further notice.

Marshall
20608 Madrona Avenue, Torrance, CA 90503
Tel: (800) 800-6608 / (310) 333-0606 • Fax: 310-333-0688
www.marshall-usa.com
support@marshall-usa.com