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January 13th, 2021 17:00
P2720DC HDMI Audio Not Working with AE515M
An AE515M sound bar is connected to my Dell P2720DC display monitor via rear USB-output.
When I connect my laptop to display with USB-C, the audio from my laptop is played from the sound bar.
Whereas when I connect my laptop to display with HDMI cable, the audio from my laptop is not played from the sound bar. Neither is the sound bar being detected as an audio devices unlike when connected to USB-C. But the display output is working.
How do I make the audio to work also when I connect to HDMI cable?
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jphughan
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January 13th, 2021 18:00
@BenisonSam Short answer: You can't. If you want audio output from an HDMI or DisplayPort source, you'd need a display with a 3.5 mm audio output jack, like some of Dell's higher-end U Series displays. You'd also need a soundbar that can accept audio input over that type of jack, even if it draws power over USB.
Longer answer: Soundbars that rely on receiving their sound data as USB require a USB data path all the way back to the source device. You have that with your laptop because the USB-C connection carries both video and USB data. But the reason a USB data path is necessary is because USB-based audio devices aren't actually "managed" as audio devices by the display. Instead, you've essentially just got a soundbar connected to a USB hub that just happens to be built into the display, and that USB hub is connected to your system. That soundbar would work even if you connected it straight to a USB port on the laptop, or to any garden variety USB hub. The laptop is handling all of the audio processing and just sending USB data out, which the display is simply passing through its built-in hub. By comparison, when you connect an HDMI source, you don't have a USB data path to the source device. Instead, your device is sending raw PCM audio over HDMI. The display won't convert that into USB audio, because again it's just passing USB data through its built-in hub rather than "managing" the audio itself. On displays that have a built-in audio output jack like I mentioned above, the display is capable of extracting that PCM audio from its HDMI or DP stream and passing it through its audio output jack.
Also note that even if you DID have a USB data path back to your source device, the source device would have to actually support USB Audio. PCs do, but as of this writing, game consoles don't, so for example if you connected a game console via HDMI and also ran a USB cable between the console and display, you still wouldn't be able to get audio output through the soundbar.