Re: [LAD] audio/midi app development

Gene Heskett wrote:
> 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@email-addr-hidden-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 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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Received on Thu Jun 17 12:15:01 2010