[mythtv-users] Onboard sound full-duplex ?

cmisip cmisip at insightbb.com
Fri Oct 15 03:14:49 UTC 2004

On Wed, 2004-10-13 at 12:03, Maarten wrote:
> Hi there list,
> I have an issue with my onboard sound card which is on my VIA KT400 board.  
> Upon first attempts I got the impression it could not handle full-duplex, so 
> I quickly added a PCI soundcard to circumvent that.  Now however, I plan to 
> add another (a second) BT878 card and I'm rapidly running out of PCI slots.
> I have to put two BT8x8 cards in, two promise 100TX2 are already in place for 
> the extra harddisks, so I will not have room for two soundcards, only one... 
Man that is quite a setup.  Does that mean you have 2+2+2+2 ide channels
because the VIA has onboard ide0 ide1 ide2 and ide3 already?

> So can anyone either confirm or deny that this card is not suited for full- 
> duplex mode, or maybe give tips / hints on how to get fullduplex working on 
> it ?  (a definitive Yes/No on the full-duplex mode -availability would 
> already help a lot).

I have the kt400 and my onboard audio is via cmedia.  I cannot get it to
work with mythtv at all.  The recording volume is too low or I get poor

> The card is reported by lspci as this:
> 00:11.5 Multimedia audio controller: VIA Technologies, Inc. VT8233/A/8235 AC97 
> Audio Controller (rev 60)
>         Subsystem: AOPEN Inc.: Unknown device 01b0
>         Flags: medium devsel, IRQ 10
>         I/O ports at e800 [size=256]
>         Capabilities: [c0] Power Management version 2
> Maybe there is another solution I just thought of:  If you can make sure that 
> mythtv _always_ uses Card_1 for playback, there should be no problems, 
> right ?  Can that be done or is that infeasible ?  I think that would be 
> impossible, seen as one cannot predict which card is free at which time, 
> correct ?
MythTV will use the sound card that you designate for playback.  It is
usually /dev/dsp which is usually a symlink to /dev/dsp0 or your first
sound card device.  You can delete /dev/dsp and recreate it to point it
to whatever sound device you want to use.  I just use my onboard cmedia
for "all other audio" playback and use a SB Live 5.1 for mythtv
playback.  I do have an ATI TV Wonder which has btaudio support so that
I need the SB Live only for the other bt8x8 capture card.  

> Failing all that, I'd need to convert to a 4-port SATA card (which would also 
> entail expensive new SATA drives! :-(( ) or any other solution, like a new 
> mainboard with more slots or other onboard sound or something.  
> I'd really like to avoid that, if at all possible.

My system has about 590 Gig of storage using 4 IDE drives connected to
onboard raid.  No promise ide controllers installed.   With the drop in
prices of 250 gig cards, you should be able to achieve a terabyte of
storage just using the onboard raid ide.

If it will help you any, I documented my mythtv install here:

It is ancient (MythTV 0.14 on a 2.4.20 kernel) with datadirect from
zap2it still using xmltv.   It works though.  The hardware config might
be useful to you.


> Thanks in advance,
> Maarten

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