Spectrum3d : software that displays the harmonics of the sound in 3D

Ralf ralf.mardorf at alice-dsl.net
Fri May 6 09:49:45 UTC 2011


OT regarding to Spectrum3d.

On Fri, 2011-05-06 at 11:03 +0200, Victor henri wrote:
> I t seems that having a rt kernel working is already very difficult; I
> believe there is already really hard work behind this... Furthemore,
> in my humble opinion, the preempt kernel becomes more and more
> interesting...

Building the kernel-rt ourself isn't difficult! AFAIK the only known
issue is regarding to the proprietary nvidia driver, which anyway could
cause issues for harder real-time.

It's correct, that more and more of the rt-patch occupies the vanilla
kernel, anyway, it's untrue that a real-time kernel can be replaced by a
preemtion only kernel.

It's correct, that just doing audio work with Ardour2 is without
problems, regarding to hard real-time issues, but if you wish that MIDI
event recordings should have a proper timing, like an analog recording
of a really good musician, than you need a kernel-rt + jack from svn
etc.. A lot of people think that it's impossible that a MIDI event
recording could preserve the groove of a very gifted musician, well,
that's a half-truth. MIDI nearly is possible to do that. Most people
aren't able to hear that MIDI isn't able to do it perfectly. What people
are able to hear, as a less good timing, is jitter. They guess that the
sequencer does play too correct, human touch should be missing, but
that's wrong. You don't need to quantize MIDI events and if hard
real-time works, it's very close to a real musician or an audio
recording. Unfortunately most of the PCs are unable to do hard real-time
and jitter will break the groove. For less gifted musicians it might
sound like the timing is to perfect, but this is wrong, it's bad timing
caused by jitter, that makes MIDI breaking grooves.

I don't like the statement that a PREEMPT kernel could replace a PREEMPT
RT. Even the PREEMPT RT should do harder real-time. Note that on
multi-tasking OS real-time seldom is real-time. The kernel-rt, ASIO etc.
don't do, what's called hard real-time. Hard real-time usually is done
by old computers and stand alone sequencers, e.g. the C64, Atari ST.

Btw. JACK2 from svn is able to do MIDI hard real-time, when using the
kernel-rt. Without JACK2 from svn, there's no chance to get this! Of
cause, I'm talking about hw MIDI and not about soft synth (Or do you
guess Hexter does sound like an old DX7 in the brown metal case? Any
analog synth emulation does sound like e.g. an Oberheim Matrix-1000? I
do use those and other old faithful synth. Btw. I'm a guitarist not a
keyboarder ;).

2 cents,

Ralf




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