Awareness | No audio support for USB-C DisplayPort (DP Alt Mode)
Learn how to troubleshoot no audio playback from USB-C DisplayPort (DP Alt Mode), to ensure devices with proper audio output.
Information
NV-21-HU can receive audio through two paths of a USB-C connection.
- The first is through the USB 3.2 path. This is how the 2x2 Soundcard and 1x1 Speakerphone are routed using AV Bridging.
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The Second is through the USB-C DisplayPort (DP Alt Mode) path, where the video is routed with embedded audio.
- Both methods use the same USB-C port.
Currently, there is no embedded audio support through the USB-C DisplayPort (DP Alt Mode) path in 9.8.1, and it won't be fixed until QDS 10.0 is released. Until then, in order to route audio with USB-C video, USB audio bridging should be used as a workaround.
Note
To use USB audio/video bridging feature in QDS, an AV Bridging License is needed. AV Bridging License will be included in NV-21-HU purchase until 10.0 is released since it is the only workaround to route audio with USB-C video.
To configure audio routing using USB audio bridging, see below:
How To | How to route audio using USB audio bridging when NV-21-HU USB-C DisplayPort (DP Alt Mode) is used
Procedure
Note
In 9.8.1, embedded audio over USB-C DisplayPort (DP Alt Mode) is not supported.
This article will provide an instruction on a workaround to route audio using USB audio bridging as an alternative to embedded audio over USB-C DisplayPort until 10.0 is released to support embedded audio over USB-C DisplayPort. Read this awareness article before proceeding.
- Enable USB Audio Bridge on the NV-21-HU Encoder.
- Route all video sources as needed.
- Place USB Sound Card In component in the design (It is going to be used as an Audio source for alt-mode DisplayPort mode)
- On the output display connected to the NV-21-HU Decoder, set Audio Source to Audio Input Pins and Audio Channels to 2. This enables an external audio source.
- Place a 2x1 stereo matrix mixer in the design. Mix Sound Card stereo audio source and HDMI stereo audio source to the mixer. Route the output to the output display connected to the NV-21-HU Decoder. The resulting design should look like this:
Note
- This workaround does not enable embedded audio over USB-C DisplayPort, it takes advantage of USB audio bridging over USB-C.
- One single USB-C cable is used for both USB-C DisplayPort video and USB Audio Bridging.
- Audio should be manually mixed since the audio does not follow the video.
- There is no breakaway audio from the USB-C source component.
- Embedded audio over HDMI functions as expected.