[mythtv-users] AC3 Passthru doesn't work on Nforce4 ALC850

Branden Stanley branstan at gmail.com
Sat Sep 16 19:32:32 UTC 2006

I struggled with this as well with my K8N neo4 platinum. I believe the
combo that "worked" was using the guide:

yum install alsamixergui
run alsamixergui
set all 'IEC958' to zero
Then the thing that worked was untick the red dots above the 'IEC958'
that only show up in alsamixergui
Set Myth audio to:
default for the mixer
Enable ac3 passthrough


**the mixer was crashing on me so I needed to kill and reload the app
4 times to get everything sorted out...

This worked for me YMMV
I hope this helps!

On 9/16/06, ubulid00 <ubulid00 at fastmail.fm> wrote:
> Using a Nforce4 Realtek CK804 sound I've been able to get 2 channel SPDIF
> outputs working great in mplayer/xine/mythv etc. However, enabling the AC3
> passthru of surround sound gives no sound in any of the utilities.
> I've removed the /etc/asound.conf file, enabled 'IEC958' and reduced 'IEC958
> Playback AC97-SPSA' in alsamixer.
> I'm getting so desperate that I even installed windows on an old harddrive
> to debug this, with the result that PowerDVD worked correctly, and VLC
> (windows) sort of worked, giving CD skipping-like audio, but the receiver
> still at least detected a digital stream. Thus I believe the hardware is OK.
> I had a post on gentoo forums for a few weeks with some info:
> http://forums.gentoo.org/viewtopic-t-493511-highlight-.html
> There is no sound output when using the linux players (xine,mplayer,myth).
> My Aiwa receiver does not detect a dolby stream (but the liba52 downmixed
> SPDIF stream is always ok).  The motherboard is a MSI Neo4 Platinium, and a
> Aiwa CK-NDS8 receiver.
> Can anyone offer some things to try to get Dolby Digital passthru working on
> Nforce4?
> --
> View this message in context: http://www.nabble.com/AC3-Passthru-doesn%27t-work-on-Nforce4-ALC850-tf2283328.html#a6342925
> Sent from the mythtv-users forum at Nabble.com.
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