Re: [LAD] audio/midi app development

On Wednesday 16 June 2010, Philipp Überbacher wrote:
>Excerpts from Gene Heskett's message of 2010-06-17 00:45:14 +0200:
>> 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
>> >>>
>> >>> <ralf.mardorf@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.
>> >
>> >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 fear something named simply 'emc' isn't easy to find around the net.
>
Go see <http://wiki.linuxcnc.net>, I am reasonable sure there are links to a
downloadable live but installable .iso there. You can run this latency-test
from the booted cd I believe.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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it holds the universe together ...
		-- Carl Zwanzig
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