Re: [jazzplusplus-devel] Thoughts about the linux kernel - observed trends

[Robert V. <vo...@ct...>]

On Fri, 2008-05-16 at 05:11 +0000, D.B. Moore wrote: 
> Greets,
> 
> > Date: Thu, 15 May 2008 22:31:41 -0400
> > Subject: Re: [jazzplusplus-devel] Thoughts about the linux    kernel  -       observed        trends
> >
> > On Fri, 2008-05-16 at 02:03 +0000, D.B. Moore wrote:
> >> Greetings,
> >>
> > (snip)
> >>
> >>
> >> I think what I eventually might do, is put some sound files up
> >> on our site, which **audibly** demonstrate to users artifacts
> >> of sound quality directly related to linux kernel latency issues.
> >>
> >> That'd be about the best thing to do...IMHO....to help users
> >> conclude whether or not they need a better (faster) kernel
> >> for their setup. Hope this helps...
> >>
> >> Regards,
> >>
> >> Donald B
> >>
> >>
> >
> > I tried Jazz++ a couple of ways, both quite good:
> >
> > * my ux16 USB midi interface hitches to a Motif ES8 which together has
> > excellent sound quality.
> >
> 
> Good to hear...(another pun ;) No timing issues? Don't be scared to be verbose
> if what you're doing relates directly to Jazz++'s performance in the real world.
> 
> 
> > * The software synth I like is ZynAddSubFX produces its own pleasing
> > sound. I use Hydrogen for its drum set. Rosegarden does this, and I
> > think Jazz++ can too. (I didn't run Hydrogen from it yet.)
> 
> If you do, be sure to let us know if it works okay.  I do know about zyn & lv2,
> in fact I've just installed that kit here on my box - but as is common with a lot
> of us here, I haven't yet found the time to play with it....but I will get to it...
> 
> >
> > Probably I need to modify the kernel to hear how good the native midi
> > is.
> >
> 
> You just know I'm going to ask what makes you think that, don't you?  ;-)
> 
> 
> Subsequent to my previous posting, and carrying my notion forward
> about putting soundfiles somewhere that people can listen to and then
> conclude whether or not they have linux kernel latency issues with their
> softsynth setup....
> 
> Pete,  can you put this attached mp3 file in..'some appropriate location'
> for me please? I'm thinking about a yet undiscussed 'FAQ' area, and
> anywhere else kernel latency issues are touched on, it'd be handy to
> be able to link back to this location...I'm sure you get the idea here ;-)
> 
> Bob, listen to the attached mp3 and the sound of the softsynth loosing
> the plot entirely, until timelag detection code realizes something gone
> terribly wrong and realigns the datastream with where the hardware
> is 'right now' as it were. .
> 
> This was rendered a few years ago now on a x86_32 with an AMD
> athlon 3000+  CPU using AMS on one of my own linux builds. IIRC
> the timing glitche started out as a 0.002 second deviance, rising to
> 0.09 second deviance before the code kicked itself in the pants.
> 
> Remember I said this area was a minefield?...yeah, well some of these
> timing related issues are not entirely the  kernel or the software's
> fault -- it can actually be related to the motherboard chipset being used
> and/or the state of play with a particular chipset's driver (in linux).
> A good example is what you hear in this mp3, which is going to be
> heard a -lot- more by folks with a VIA chipset mainboard (x86),
> because this is a known issue with linux/VIA chipsets, and it doesn't
> affect just the things we're talking about here - DMA and interrupt
> issues with VIA chipsets can plague the video, fb, any manner of things..
> 
> ....and, just as an example of HOW weird and obscure this can get,
> I have a VIA epia-tc10000 board here that initially gave me all sorts
> of heck, and I did hours and hours of mucking around with it before
> I discovered the effective fix was actually to email the VIA techsupp
> crowd about it, who replied with a link to a beta version BIOS image
> ...so the problem was in BIOS all along, and seemingly only affected
> use with a linux kernel...go figure...
> 
> Oh...and for the record, what you're hearing in this sound snippet,
> (the sound you're supposed to hear :), is a free running AMS patch
> I did up for an arty friend who wanted some kind of eerie spacey
> sort of ambiance as a sound prop for her display installation. I used
> to call this patch "Trapped on a Dalek spaceship with the BBC
> Radiophonic Orchestra"   ;-)
> 
> Regards,
> 
> Donald B
> 
> 

Hi Donald,

Your mp3 sounds pretty good to me...except it's a little scratchy.
Perhaps that could be filtered out ?

I am running the standard Debian kernel using a dual-core 3.0 Ghz
processor. I'm thinking that it would be better if I went with the
64studio distribution or, even beyond that, upgrade to a 64 bit
processor, but that will be a few months away.

Jazz++ performs pretty well with  a small number of tracks, but I did
notice if rendering a 16 track file it does break up some. 

The metronome seems to work now...although the sound is not right.
Definitely not a drum sound.

Aconnectgui, when I try to do additional configuration, locks up badly.
So much that I couldn't kill it and at one point had to forcibly power
down. There has to be a problem with it.   

Bob