Re: Real-time category

[Kim Flint <kflint@loopers-delight.com>]

At 03:05 AM 12/5/2005, Stefan Tiedje wrote:
>I just found this quote on the Loopers-Delight page where all the 
>software 
>loopers are listed:
>
>"PC/Mac software doesn't get to be in the real-time category, cause if it 
>runs on MacOS or Windows, it can't honestly be called real-time! It can 
>still be very powerful stuff, though...."
>
>I don't understand the quote, its obviously wrong, I do realtime looping 
>since more than a decade with software running on various OSes, mostly OS 
>X now. There must be a debate about it...

Windows, MacOS, and Unix/Linux are general purpose, non-realtime OSes. A 
real-time OS (RTOS) is a special variety of operating system that 
guarantees a specific time in which any command will be executed. No 
matter 
what the system is doing, the command will execute in time. RTOS is 
commonly used in timing critical applications. Looping happens to be a 
very 
time sensitive application, since users constantly interact with it in a 
rhythmic fashion and timing inaccuracies tend to get multiplied as the 
loop 
repeats. Also, there are often precise synchronization requirements that 
need reliably exact timing. That is why all dedicated looping hardware 
uses 
an RTOS. Many loopers like having reliable timing, so this is an important 
issue to them.

In a non-realtime system (like windows/mac/linux), a command cannot be 
guaranteed to execute within a specified time. Most of the time however, a 
command will execute quickly enough. So it may seem "realtime". But there 
is always some probability that a command will get delayed longer than 
expected. You can't depend on the timing accuracy of the system 100% of 
the 
time. Some people don't seem to mind that unreliability, others do.

>I am sure I can setup my instrument faster than any looper with more than 
>2 hardware loop devices.

it isn't a question of setup time. (that is a user interface issue.)

>And most hardware devices run software within their own OS.

They all do. It isn't a question of "software vs hardware". That is 
meaningless since in all cases we are talking about software running on 
hardware. The issue is "realtime vs non-realtime". Designers of dedicated 
loopers all choose real-time OS for their system architecture. 
Windows/mac/linux software applications do not have that choice.

>Hardware can even crash...

of course. that isn't the issue either.

>(Kyma is listed as hardware, though its software, the accompanying 
>hardware is called Capybara ;-)

That's a good point, it should get clarified. However the Capybara is 
running its own RTOS, and that is where all the sound processing happens. 
The category on the LD tools page is called "Real Time Loopers" not 
"Hardware Loopers". That is why Kyma is in that section.

kim


______________________________________________________________________
Kim Flint                     | Looper's Delight
kflint@loopers-delight.com    | http://www.loopers-delight.com