17 Jun
2010
17 Jun
'10
8:06 a.m.
Gene Heskett wrote:
On Wednesday 16 June 2010, Patrick Shirkey wrote:
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
On 06/17/2010 04:52 AM, Ralf Mardorf wrote:
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. ;-)
Paul Davis wrote:
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?
On Wed, Jun 16, 2010 at 2:30 PM, Ralf Mardorf
<ralf.mardorf(a)alice-dsl.net> 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.