Re: [linux-audio-dev] News about sequencers (not my own though!)

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Subject: Re: [linux-audio-dev] News about sequencers (not my own though!)
From: David Olofson (audiality_AT_swipnet.se)
Date: pe tammi  21 2000 - 21:18:23 EST


On Fri, 21 Jan 2000, Paul Winkler wrote:
> > you have to
> > buffer the results (and output them using some streamlined function,
> > preferably in native code),
>
> newbie question: what is "native code" anyway?

Code compiled (and hopefully optimized :-) for the hardware you're
using.

> > to get rid of the jitter that grows with
> > execution time.
>
> Does this mean that timing tends to get increasingly erratic as the
> run goes on?

No, what I meant was that if you do

        ...
        ...some code...
        ...
        output_data(...);
        ...
        ...some code...
        ...
        output_data(...);
        ...

you'll get latencies between the output_data(...) statements. If your
code takes up a great deal of the process cycle, these latencies can
become significant, especially if it's posible that the order of the
output_data(...) statements change in relation to destinations.

Using time stamps and a simple real time engine to output the results
should replace this problem with a constant latency.

(This is pretty much what the time stamped event system of MuCoS is
meant for; getting sample accurate timing without running the engine
one sample period at a time. You can stream MuCoS events from a
"soft" real time source with seconds of buffering and still get the
same accuracy in the output result.)

//David

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