[nas] [PATCH] voxware server: using different in and out devices

Jon Trulson jon at radscan.com
Fri Aug 11 18:07:29 MDT 2006

yOn Fri, 11 Aug 2006, Erik Auerswald wrote:

> Hi,
> On Thu, Aug 10, 2006 at 10:16:27PM -0600, Jon Trulson wrote:
>> On Thu, 10 Aug 2006, Erik Auerswald wrote:
>>> To really use two sound cards we would need two mixer devices as well.
>>> At the moment we only use sndStatOut.mixer.
>>      I would think you would run a seperate server for each sound
>>      device wouldn't you?
> That depends. Obviously the idea of different input- and output-devices
> was to circumvent the OSS half duplex drivers. Today this problem should
> be solved by using ALSA drivers. I don't know if there is actually half
> duplex sound hardware used in current consumer devices.

         Hmm... I think this was done (would have to check) for certain
         devices (like 'professional' devices) that actually do use a
         seperate dsp device for input and output... I seem to vaguely
         recall adding this for a user that had one of these devices.

         It may have been a driver implementation detail though for
         this particular device.

         Some devices are indeed only capable of half-duplex operation
         (say in the output section), but do this via the same device.
         You will see code in voxware that checks for failures when
         opening a device read/write, and plays a game when this

         I have an old SB PCI - it does support FDX operation; I've
         never been in posession of a half-duplex card, but some nas
         users sure have :)

> So back in the day one would want to run one NAS server making use of
> two half duplex soundcards (sound blaster...) and would have to use two
> mixer devices to control them. It seems noone actually did this as it is
> not fully supported by the voxware server...

   Well, a single nas server should handle a single device, half or
   full duplex.  For multiple devices, a nas server should be run for
   each... Steve McIntyre added a patch back in 2004 that allowed you
   to specify a different nasd.conf file on the nasd commande line
   specifically for this purpose.

> In my case I configured the S/PDIF out of the on-board sound as one OSS
> device and the normal "analog" in/out hw as another. The sound card
> mixer controls all of these devices so I don't need seperate mixers.

   I'm confused... You really only have a single sound device right?
   It may have multiple outputs, but it's still a single device?

Jon Trulson
mailto:jon at radscan.com http://radscan.com/~jon
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