[music-dsp] Linux or Windows or BeOS for Audio Processing

[David Olofson]

On Saturday 10 February 2001 00:43, emerson tan wrote:
> Hello! Over the past few days or weeks, I've read so much mail on
> this list about using Linux or Windows or BeOS for Audio Processing
> projects. Much have been argued upon over the
> latency/timing/realtime issues.
>
> Have anyone ever used QNX (www.qnx.com) Real-time Platform for
> audio-dsp processing?

No, but I was very close to go there. Way too expensive per system 
licenses for many applications, though...


> I'm interested to know the
> latency/timing/realtime issues under QNX.

Basically none; QNX is a *real* RTOS in the same class as RTLinux and 
RTAI, only designed that way from the ground up. Would be absolutely 
perfect - if there were drivers, a serious desktop environment, wide 
user base etc, but it's not just the right kind of OS to get there. 
(If people are still arguing against GNU/Linux for those reasons, QNX 
is miles outside the picture...)


> I'd like to know
> particularly if it would be worth the time to learn it.

If it works for you, and you're not worried about porting drivers (at 
least parts of ALSA has been ported, AFAIK) and applications, and 
paying around $1000 for every complete system, sure, it's a very high 
quality *hard RT capable* RTOS, so there should definitely not be 
latency problems.


> QNX was famous in real-time environments from small hand-held
> devices to large- scale industrial automation systems.

That's what it's designed for, which explains why it's so good at it. 
However, you may run into trouble very quickly when trying to do 
"ordinary" things.


> The QNX RTP
> might probably be a good alternative to Linux/Windows/BeOS.

If you're going to deal with an OS that's not meant for desktop 
systems in the first place, why not throw RTLinux or RTAI into your 
kernel? Both can do RT signal handlers in user space these days, so 
you don't have to run your engine in unprotected kernel space, but 
you still get all the way down to the very audio card latency limits.

I'm not dismissing QNX as an interesting audio platform, but I'm 
having some trouble seeing why one would prefer it to an easy to 
install, mainstream Red Hat Linux distro with KDE and/or GNOME 
desktop environments on top of a hot X server working out of the box, 
and a Linux/lowlatency + RTL/RTAI kernel...

For desktop systems, that is. Personally, I'd still strip an RTL or 
RTAI system down if I were to do something embedded with ultra low 
latency (well, I'm actually doing just that at work), but QNX would 
probably be just as suitable for that, at least from the technical 
POV. 


//David

.- M A I A -------------------------------------------------.
|      Multimedia Application Integration Architecture      |
| A Free/Open Source Plugin API for Professional Multimedia |
`----------------------> http://www.linuxaudiodev.com/maia -'
.- David Olofson -------------------------------------------.
| Audio Hacker - Open Source Advocate - Singer - Songwriter |
`--------------------------------------> david at linuxdj.com -'


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