From alsa-user-owner@alsa.jcu.cz  Wed May 20 03:42:37 1998
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Date: Wed, 20 May 1998 02:41:02 +0100 (BST)
From: Stephen Oxley <so101@york.ac.uk>
To: alsa-user@alsa.jcu.cz
Subject: Better SB16 ViBRA16X PnP support?
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Hi, I've had nothing but trouble with this card, I hope someone can help.

1. I have been able to play sound and record sound but not both at the
same time. - half duplex -

2. The sound quality isn't as good as when using oss-linux (module driver) 
or oss-free (compiled into kernel, but in module form), hiss in the
background -not as clear reproduction of sound-, which makes me think I
only have 8 bit sound available under alsa. 

I believe the problem to be that this sound card doesn't have a 16bit dma
channel but two 8bit dma channels (perhaps only one!, although I did read
somewhere that it is supposed to be able to do hardware full duplex and
this is achieved nicely under windows), instead of the usual sound blaster
one 16bit and one 8bit configuration.

Both of these 8bit channels can be allocated to dma 0,1 or 3 and that is
where the configuration problems start. Alsa can only recognise one of
these channels and presumably thinks that it can only play 8bit sound
through it. 

>:/proc/sound/0$ cat sb16
>SB16 DMA usage
>
>Shared DMA    : 8-bit

Does anyone know a hack firstly to allow me to have full duplex support
(preferably under speak freely) and secondly to improve the sound quality?

I'm hoping to use the alsa driver in the long run rather than either of
the two mentioned earlier. Mainly because the free compiled kernel driver
completely freezes up my system on a daily basis and has no FD support and
the other oss-linux driver costs money and the FD support isn't as
complete. 

My kernel is 2.0.33 and i'm using a slackware distribution.

Thanx for any help given.

Stephen Oxley.



