snd_hda: how to configure line-in passthrough to line-out?

[Polytropon]

On Tue, 4 Oct 2011 20:58:14 -0700 (PDT), Brandon Kuczenski wrote:
> I'm working on the sound on my system running 8.2-RELEASE.  Currently I 
> have sound input and output working using snd_hda (i.e. I can record on 
> line in, and play it back on line out).
> 
> What I would like to do is take the audio coming in on line-in and send it 
> back out the line-out "live" without recording it.
> 
> Is this easy to do?  I'd appreciate any hints.

I think it is easy to do. If I remember terminology
correctly, the thing you're searching for is MONITOR.
Instead of setting rec source to mic, set it to line,
and increase monitor level.

The line level should be possible to set independently
of the rec channel setting, so you should be able to
pass through line anyway - at least, that has been the
default ability of sound cards when they became available
for PC. But well... this has been 10... 20... years ago,
and nobody expects simple things to work as simple today
as they did in the past. :-)

On the line out channel, all input should be "accumulated"
according to the individual levels (pcm, line in, mic);
the setting which source to _record_ from is handled
independently.

Refer to "man mixer" on how to set the levels as you
require.


-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...