USB sound device questions (multiples!)

Daan Vreeken [PA4DAN] Danovitsch at Vitsch.net
Wed Jan 21 00:47:38 PST 2004


On Wednesday 21 January 2004 02:53, Ethan wrote:
> Hello all,
>
>  I am thinking about trying to use 4 to 6 USB "sound devices" on a single
> FreeBSD system.
>  Can anyone advise me if I will run into a case where on every reboot they
> all get different pcmX devices? Or will they stay static?
If they are all plugged in during boot they will get probed in the same order 
every time you boot, so yes, they will be static.
Be sure to calculate if you have enough bandwidth available to drive such a 
great number of devices at the same time though :
48KHz * 16-bits sample * stereo * 6 devices = about 48 * 2 * 2 * 6 =
 1152 KB/sec .
That's about the maximum you can get over USB 1.0, so I'm not sure if you will 
be able to use them all at the same time at maximum playback rate... So it 
depends on the quality and sample-rate you need.

grtz,
Daan


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