Re: [linux-audio-user] Multi-channel audio with a computer front end

On Monday 15 January 2007 08:54 in an email titled "Re: [linux-audio-user]
Multi-channel audio with a computer front end" Paul Davis wrote:
>in other words, i'm totally confused by your goals.
>
>--p
Thanx Paul. Here is what i am trying to do. I want to use my computer as a
front end in a multi-channel system with a little as possible between it and
the amplifiers for purities sake. I do not want D/A conversion inside the PC
as that is noisy and jittery. I do not want to use spdif or toslink as those
are also jittery (or so i understand).

The Slim Devices (squeezebox or Transporter) are fine for stereo but will not
work for multichannel due to latency issues. You can send a digital signal to
a pre/pro from them but that adds a pre/pro in the mix and i'd rather not.

So that leaves me with usb or firewire.

I have seen a few pro audio D/A converters devices that are multi-channel such
as the Apogee rosetta 800
(http://www.apogeedigital.com/products/rosetta800.php). The ones that can do
24/192 (which is also a goal here) are firewire devices. I have also seen
some that are USB based but are 24/96 only. That is not as good, but
acceptable.

Can my system send all the channels to one of these devices via usb or
firewire and have the device break them out and send them to the appropriate
speakers. These devices know nothing about DTS, DD and the like so the
computer would have to determine what sound goes into what channel and send
all that to the device. I know that were i using a mixing like Audacity or
Audour it could be done, but the question is can the media player engines
(gstreamer or xine) do that as well?

If that answer is "no", then i can move the attention down to stereo USB
devices. Since linux can use multiple sound cards i could purchase 3 stereo
USB devices. Could I have Xine or Gstreamer send the front channels to one,
the centers to another and the l/r rears to another? If so, am i going to
run into a problem with timing issues between the 3 devices? Is USB going to
cause such latency problems?

I could send it all out digitally and just let a pre/pro handle it. However,
then i am limited to what the pre/pro understands and i want to play with
things like ambiophonics and such. I'd also like to do a little mixing and
recording and a pre/pro isn't meant for that.

I reailse that using usb/firewire in this way will result in my using digital
attenuation instead of analog. This is not ideal, but could be solved with
passive volume controls on the other end. However, since i am looking at
24-bit and my listening levels are quite low it should not introduce any
limits in the audio resolution.

If i need to explain further i am happy too.

Thank you.
Received on Mon Jan 15 20:15:05 2007