At Sun, 25 Aug 2002 14:07:30 -0700 (PDT),
gson@gson.org wrote:
> By examining the wav file using WaveSurfer (now in pkgsrc as
> audio/wavesurfer), I found that the clicks occur 2400 samples apart,
> which corresponds to the block size of 4800 bytes reported by
> audioctl.  Each click consists of four samples of signal from several
> hundred milliseconds back, presumably from the previous cycle through
> the circular recording buffer.  Note that since the clicks consist of
> previously recorded signal, a recording of silence will not exhibit
> audible clicks.
> 
> A waveform display of a typical click can be seen at
> http://www.araneus.fi/gson/netbsd/bugs/autri-click/click.gif,

This seems to be quite similar to kern/16385 in two points:
 - the shape of clicking noise
 - no noise when recording silence,
although the clicks weren't periodical in my case.

So I guess the bug is in the common audio layer, not in autri or
uaudio.

--
IWAMOTO Toshihiro