21 May
2006
21 May
'06
6:15 a.m.
c wrote:
On Sat May 20, 2006 at 09:27:56AM -0500, Gene Heskett
wrote:
If you are using alsamixer to set gain levels, that currently it is kind
of hit and miss as to what 100% actually means.
On some cards 100% is 0dB gain, on others it can be +12dB gain.
So, setting your control to 100% might be causing a +12dB gain to the
signal, that of course would over drive it and cause clipping.
I will be implementing at some point, support for displaying dB gain
values in alsamixer, so the problem you are having will disappear,
because you will be able to then tell exactly what position to put the
gain slider to get 0dB gain.
James
often sounding as if the playback is of a file
that over-drove the d/a in playback, or the a/d in the recording, eg clipped.
...
the ATI-IXP audio stuffs loaded
the ATIIXP in my MSI exhibits this same issue. essentially, if the 'PCM' level is
set to 100%, things are horribly overdriven. the solution is to set the Master to 100%,
and adjust volume with PCM, instead of vice versa. i guess whether this is a hardware bug
or a driver bug depends on if PCM is the last point of software contact with the stream
and master trims the levels after that, or if PCM just does some multiplication on the
bits before passing them to the Master..