device is a device name. On Linux, it is the ALSA string. On Windows, it is currently ignored, so you should pass "default" or null so when it does get implemented your code won't break.
Added Nov 8, 2020.
The D Programming Language's Unofficial Docs
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device is a device name. On Linux, it is the ALSA string. On Windows, it is currently ignored, so you should pass "default" or null so when it does get implemented your code won't break.