Subject: Re: [linux-audio-dev] XAP: Ansynchronous Streaming Protocol
From: David Olofson (david_AT_olofson.net)
Date: Sat Dec 14 2002 - 00:56:52 EET
On Friday 13 December 2002 20.54, Steve Harris wrote:
> On Fri, Dec 13, 2002 at 07:46:37 +0100, David Olofson wrote:
> > > Linuxsampler requires very tight interaction between the
> > > streaming code and playback code to work.
> >
> > Yes. You need to be able to tell the "butler thread" which files
> > to load/cache, and it may need to know the maximum bandwidth you
> > will use, so it can set up sufficient caching - if there's a
> > point in being that picky, that is. (Streaming from disk is
> > nondeterministic enough that the difference in latency between
> > starting a 48 ksamples/s stream and a 96 ksamples/s stream
> > becomes insignificant.)
>
> Theres more to it than that, you have to also be aware of loop
> points, layers etc.
Loop points are basically extra start points that need to be cached,
and layers mean more waveforms to deal with. The logic is still the
same, though.
> Realisticly it has to run as a mutithreaded process.
Well, people used to say that about real time music software in
general... Things change.
Either way, a plugin with a bunch of worker threads (created by the
plugin directly, or via a host provided API) wouldn't be a problem.
It's basically what you have already; just different APIs.
Splitting the butler thread and the sampler isn't required, of
course, although it would be cool if you could use the same butler
for all streaming from disk, be it for the sampler or HDR. (Though
the latter implies that there has to be streaming *to* disk as
well... *hehe*)
//David Olofson - Programmer, Composer, Open Source Advocate
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