Internal microphone on ThinkPad T490 (azalia0, Realtek ALC257) records silence. Playback works.
How to repeat: run aucat -o /tmp/mic.wav, speak, stop with Ctrl-C, play back with aucat -i /tmp/mic.wav. The recording is silent. Same result with the headphone jack unplugged. State: kern.audio.record=1, input.mute=0, input.level=1.000, inputs.mic=255,255, record.adc-0:1_source=mic, record.adc-2:3_source=mic2,mic, record.adc-4:5_source=mic2, outputs.mic2_sense=unplugged. Same laptop records correctly on Debian. FreeBSD shows the same silence, reported as FreeBSD bug 296398, which describes the internal microphone as digital. I have not verified that on OpenBSD.
