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I have a pair of USB-C active noise cancelling headphones, and I'd like to use them with the in-flight entertainment system of an airplane. A typical in-flight entertainment system comes with either a 3.5mm jack or a double-pronged jack for audio, as well as a USB-A female receptacle for power only.

Adapters from a double-pronged jack to a 3.5mm receptacle are very common, and so are adapters from USB-A male to USB-C female. But what seems to be impossible to find is a converter from either the double-pronged jack or the 3.5mm jack to a USB-A or USB-C female receptacle.

I understand that the 3.5mm jack contains an analog signal, which has to be converted to a digital signal for the USB output. Furthermore, power has to be drawn from a separate source to do that, but I can get power from the power-only USB-A receptacle on the plane.

Does the converter I need exist? This converter should have two inputs (USB male for power only, and 3.5mm jack or double-pronged jack for analog audio) and one output (USB female).

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  • My idea would be to convert the analog signal to a digital signal (S/PDIF or I²S audio) first and then use some sort of capture device to convert this to something the DAC in an USB C headphone can understand. Ask hifimediy.com and report back.
    – chx
    Jan 7 at 14:36

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You will likely need something with enough compute to talk to the USB digital audio device presented by the USB-C connector, as well as an ADC to sample the analogue audio. This is a fairly complex device since it needs to run a full USB host stack.

I don't know of a product as such, but it could be done with a board like a Raspberry Pi with an audio input - either via a HAT or a USB line in adapter. That would need a small amount of software config to make it work.

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  • Pi Zero + Zero4U usb hub + plugable USB sound card + active C female to A male adapter would do it. You would need to run a tiny program which replays the audio from the microphone in to the USB C headphones. Not the best audio quality for sure. There are other audio Zero hats which might be better.
    – chx
    Jan 7 at 15:11

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