Re: [LAD] hard realtime performance synth

From: Louigi Verona <louigi.verona@email-addr-hidden>
Date: Wed Jan 27 2010 - 03:34:45 EET

Hey!
Bristol synths are very good, but I have problems with them. They do run on
my system, but I am not able to use most of them reliably, since if you play
fast or play a long succession of notes, the synth simply uses up too many
resources and eventually gets kicked out of jack. So my dream to use all
those synths in a real-time performance are still only dreams. I have been
in close contact with the developer and as far as I understood he does not
have such an issue on his machine. He will soon release a new version and
we'll see how it goes, but at the moment Bristol synths seem to be using too
much resources to be used for live performance and my machine is nowhere
near being old, with a DUO P8600 CPU and 4Gb of RAM it should fly.

Louigi Verona.

On Wed, Jan 27, 2010 at 4:15 AM, David McClanahan <
david.mcclanahan@email-addr-hidden> wrote:

> Hi,
>
> Thanks for the response. Some thoughts
>
>
> 1. Bristol synth was one the first synths I tried. I had installed
> Ubuntu(Karma I think. BTW: Ubuntu is based off Debian and that packaging
> system didn't seem to save me from breaking things) and then used various
> "apt" commands suggested on the Ubuntu Studio site to install sections I
> wanted(including the "realtime" kernel). When I ran Bristol(or ZynAddSub for
> that matter) it would lockup and not even display the keyboard interface. I
> eventually discovered that networking(the loop device interface) was not
> hooked in. I got a little further in that graphic interface came up and I
> got a plink or 2 before lockup. I'll take a look at the suggestions given
> however.
>
> 2. As for some of other suggestions, I don't care what interface(X11,curses
> etc) is available on the sound host(the dell in this case). As long as I
> could control it and get some usable status output that'd be ok. (I'll check
> into linux sampler). I could see it functioning perfectly well via some
> midi/serial connection which I think ALSA has.
>
> 3. I'm a little worried about what some are calling realtime systems. The
> realtime system that is part of Ubuntu Studio and others may be more
> preemptible than the normal kernel(as in kernel calls themselves can be
> preempted), but that's not a hard realtime system. A hard realtime
> system(simplistic I know) might entail a task whose sole job is to pump out
> a sinusoidal sound sample to the D-to-A on the sound card. A hard realtime
> scheduler would run that task at 44Khz no matter what. This would entail
> developing code that when the machine instructions were analyzed, would run
> in the time constraints(aka the 44Khz). RTLinux appears to be suitable and
> RTAI might be. Perhaps others.
>
> The way things are now even with the "realtime kernel" on U. Studio. ,
> xruns can occur because there's no hard limit on accessing resources-only
> priorities. This may work fine on newer/faster machines but not on the older
> ones. Some may say, "Go buy a faster machine". My answer is that won't
> necessarily solve the problem which is a proliferation of "systems" on top
> of systems without any assurance they'll all work together on time. I could
> go buy a new systems but I have the feeling I'd be still "tuning" to get
> things running. Roland, Korg, Yamaha put out turnkey products on what I
> suspect is simpler hardware and my question is there any reason why similar
> turnkey systems could not be developed on a Linux system(even on an older
> machine). There may be some reason. I just don't think I've heard it yet.
>
> david
>
>
> David
>
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>
>

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Received on Wed Jan 27 04:15:02 2010

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