Subject: Re: SPDIF and NetBSD 4.0?
To: Giles Lean <>
From: Jukka Marin <>
List: netbsd-users
Date: 12/11/2007 17:57:57
On Tue, Dec 11, 2007 at 10:34:34PM +1100, Giles Lean wrote:
> Jukka Marin <> wrote:
> > Does NetBSD support digital (SPDIF) audio output with some audio
> > card(s)?
> Yes -- I haven't tested with 4.0, but used a Zoltrix card with the
> cmpci(4) driver on earlier releases. I expect other drivers work too.

Well, I downloaded the datasheet of the codec used on this motherboard
(ALC655), found the SPDIF output pin (48), checked it with oscilloscope
(with mixerctl -w spdif.enable=on) and saw a promising pulse train.

I soldered a wire to the pin, added two resistors and capacitors (as
shown in the ALC655 datasheet) and - it worked.  The only problem so
far is that the analog inputs of the codec are not digitized and output
to SPDIF, so all I can hear is the digital (PCM) output.

> Typical issues:
> o most chips resample 44.1kHz audio to 44kHz (you may or may not care)

Hmh, this codec appears to support 44.1 kHz, but only for SPDIF input.
Output sample rate is fixed to 48 kHz. :-(  It doesn't sound all that
bad, but mp3's never sound real good, either.

> Sorry for the length of the rant.  I'm a consumer with an unmet
> need^H^H^H^H want.

I could use a good digital audio in/out box with NetBSD support, too.