Re: [Linuxsampler-devel] Hi - Very quiet list - my first post

[David O. <da...@ol...>]

On Monday 20 January 2003 19.18, Mark Knecht wrote:
> > -----Original Message-----
> > From: lin...@li...
> > [mailto:lin...@li...]On Behalf
> > Of be...@ga...
> > Sent: Monday, January 20, 2003 9:36 AM
> > To: lin...@li...
> > Subject: Re: [Linuxsampler-devel] Hi - Very quiet list - my first
> > post
> >
> >
> > Perhaps it would be beneficial for all us to implement
> > LinuxSampler as a XAP plugin ? who knows ?
>
> I don't think I 'know', but I can report some data.
>
> This could work, in some applications, but (for me anyway) it might
> have limited appeal.
>
> In the GigaStudio world the sample libraries are huge, mostly
> running between 1-2GB per library. I use 10-15 of them at a time,
> so there is no way to put this in DRAM. This puts a pretty high
> stress on the underlying disk subsystem, which is fine as long as
> GSt is on it's own computer where the PCI bus and audio subsystem
> are available to do the work. So, in replacing something like GSt
> or Halion, my guess is that LinuxSampler wants to look mostly like
> a stand along application.

I see - and in that scenario, it doesn't really matter whether=20
LinuxSampler is it's own host, runs as a JACK client, or runs as a=20
XAP synth under another host. The difference is in the APIs and what=20
they provide.

Stand-alone app:
=09+ No restrictions!
=09- ...and no definitive standards. Just pick some protocols.

JACK client:
=09+ You don't have to worry about audio I/O.
=09+ Audio routing can be handled by other tools.
=09+ No lib conflicts, as you can have your own process.
=09- Linux still breaks JACK out-of-process latency... :-(
=09- There is no instrument control protocol.
=09- Control and audio run on different subsystems.

XAP plugin:
=09+ You don't have to worry about audio I/O.
=09+ There is a comprehensive instrument control protocol.
=09+ Control and audio routing and transport is integrated.
=09+ You're running in-process, which works well on any LL kernel.


(Note that these are not necessarily absolute facts. It's just based=20
on my own observations and information from the lists.)


> That said, it would be very cool to be
> able to send it control commands via the MIDI stream, or over
> Ethernet, from my main DAW. GSt doesn't support much of that today.
> (If at all...I don't use it.)

That's just a matter of the host mapping MIDI to XAP controls in a=20
useful way. What you need is a MIDI->XAP translator - and you could=20
send a custom one with LinuxSampler, to implement SysEx or whatever=20
you like. (It's just a driver/plugin, just like the interfaces to=20
ALSA, JACK and whatnot.)

Audiality implements MIDI internally for now, since it's not a=20
plugin. I just picked OSS + ALSA "rawmidi" is the control interface=20
and SDL + OSS for audio I/O, since that's what worked best for what I=20
needed at the time. (There was no XAP when I started hacking=20
Audiality, and it's still not finalized - and either way, there's no=20
host.)


> If we were looking at a trimmed down version of the technology
> which operated more like Battery, then I think that using the
> underlying sampler technology as both a plugin or a stand alone app
> running on the same DAW, if most of the samples fit in memory.
> (Easy for drums, not so easy for piano)

What exactly do you mean by "stand alone app"...?

By my definition, the only difference between a completely=20
stand-alone application and a plugin + GUI process is that in the=20
latter case, the RT thread belongs to another process.

This has no implications to users (if they even know about it!),=20
except that the latter will probably interface better with host=20
applications than will something that uses MIDI or similar in=20
parallel with JACK audio streaming.


//David Olofson - Programmer, Composer, Open Source Advocate

=2E- The Return of Audiality! --------------------------------.
| Free/Open Source Audio Engine for use in Games or Studio. |
| RT and off-line synth. Scripting. Sample accurate timing. |
`---------------------------> http://olofson.net/audiality -'
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