linuxaudio.org

Gene Heskett wrote:

quoted text
> On Wednesday 16 June 2010, Patrick Shirkey wrote:

>

>> On 06/17/2010 04:52 AM, Ralf Mardorf wrote:

>>

>>> Paul Davis wrote:

>>>

>>>> On Wed, Jun 16, 2010 at 2:30 PM, Ralf Mardorf

>>>>

>>>>  wrote:

>>>>

>>>>> PS: Why not programming for savant syndrome musical gifted and 'fast'

>>>>> watching people too?

>>>>>

>>>> the limits under discussion relate to monitor technology, not human

>>>> capabilities.

>>>>

>>> I'm not a 'fast watching savant' ;) and even if the GUI is too slow, I

>>> won't care. I'm listening to music with my very good ears, but my bad

>>> eyes. No doubt, Linux is a good choice, but MIDI real-time could be

>>> better. For me the GUI is unimportant. BUT I prefer to do audio

>>> recordings using Linux, but MIDI recordings. It's a real pity, because

>>> MIDI would add some very cool features.

>>>

>> This is only on your system right? I know a lot of people are working

>> with midi recording using linux tools.

>>

>> You see jitter at low latency but have you tried changing your hardware

>> or working with the driver developers to isolate and fix the bugs you

>> are seeing?

>>

>

> One of the test tools that might be enlightening for the MIDI folks here, is

> the machine control program called emc.  Because jitter is very important

> when feeding a stepper motor controller a steady heartbeat at high audio and

> somewhat above frequencies, the coders have developed a 'latency-test'

> script, which you run on one screen, then abuse the heck out of the machine

> doing other things, (browsing the web, moving windows around, compiling a

> kernel, whatever warms up the cpu) then come back half an hour or more later

> and read the average and worst case latencies as displayed in nanoseconds.

>

> Those are generally big figures so do the math and make milliseconds out of

> them.

>

> Emc when running stepper motors is fussier that all get out, and that tool

> just might point the finger at truly bad motherboard, or video hardware.

> FWIW, an nvida video card, can only be used in a machine running emc if the

> vesa driver is selected, all the others including nv, tie up the interrupts,

> sometimes for many milliseconds.  For emc, that would equal a stalled motor

> and a wrecked part you were cutting at the time it stalled.  Similar things

> can be said about the APCI of some motherboards.  If that can't be fixed via

> a bios setting, toss the board.  Via chipsets seem to be the most popular in

> this latter category.

>

> If its a complex part that you've already got several hours worth of carving

> & cutting tool wear into, that will only happen once, because whatever the

> culprit is, gets both found and a free airmail trip into the bin.

>

> What?  Oh, I'll go back to lurking now. ;-)

>   

I guess you are regarding to http://linuxwiki.de/EMC, but I just started

searching the web. Btw. when 'we' some old dino computer freaks

controlled stepper motors by DOS machines, we just controlled remoted

pics (oldish micro controllers - but not very old -, I guess you would

use DSPs or other micro controllers today, but would you use your MacOS,

Windows, Linux instead of external chips for fast and exact real-time

control?). While oldish machines without multitasking, e.g. the Atari ST

could control machines on real-time, at least for applications like

MIDI, I don't know if the Atari would be able to control a CNC machine,

I guess there are reasons for using external micro controllers when

controlling such machines, not only when using a MacOS, Windows PC,

Linux PC I never heard of MacOS, Windows PC, Linux PC that are used to

do it directly, without help of external micro controllers. But I hear -

never tested it myself - that Nuendo (for Windows) should be the first

and only MIDI capable PC software.
If jitter for MIDI is depending to chip sets - and I do belief that the

chip sets are important - why aren't there trustful black- and

whitelists for that hardware?
I should shut my mouth and lurk too.
Ralf

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