Re: kern/55687: Slowed down/noisy recording with audio(4) (probably incorrect sample rate)

[Tetsuya Isaki <isaki%pastel-flower.jp@localhost>]

Thank you for detailed report.

This uploaded WAV file appears to have four channels data like as
L,R,0,0, L,R,0,0, ... in 48kHz, despite WAV file header says two
channels 48kHz.

I found that this is because of record source has two inputs at
the same time on mixerctl.  You will solve it by selecting one
recording source:

 # mixerctl -w record.source={ADC01|ADC02}

I could reproduce it on NetBSD 9.0 and 7.1 hdafg on my laptop,
so this is not a new problem.
(And I agree that mixerctl is not user-friendly...)


For details:
In device attachment phase, MD driver(hdafg) reports supported
hardware formats (including number of channels or frequencies)
to MI audio layer.  MI layer and MD driver agree it with each
other.  In this case, MI and MD agree to record on stereo 48kHz.
But since there are two recording sources on mixerctl, hdafg
actually transferred four channels 48kHz of data during recording.
Although I don't know that what benefit or functionality does
multiple record source selection have, at least hdafg should be
fixed not to transfer unreported (and not agreed each other)
format data.

I'm not sure but... should hdafg (or mixerctl?) be able to select
only one record source at the same time?

Thanks,
---
Tetsuya Isaki <isaki%pastel-flower.jp@localhost / isaki%NetBSD.org@localhost>