Re: [Linuxsampler-devel] recompilation and inlining LADSPA speed issues, looping, enveloping

[Steve H. <S.W...@ec...>]

On Tue, Oct 29, 2002 at 07:50:32 +0100, Benno Senoner wrote:
> Ah interesting, so there are problems when the inner loop is getting to
> big.

Yes, mostly for the cache reasons you mentioned.

> Any ideas what the best compromise looks like (of course it depends from
> the cache size but it would be cool to have a method to figure it out).

I think it would be hard/bad to try. Refactoring C(++) code is really
hard, I think its best to leave it as atomic as the DSP programmer made
it. You wil be supprised how efficient it is, modern CPU are heavily
optimised for small loops.

> regarding the CV stuff. Is CV the ideal (and efficient) model to use in
> a sampler ? Excuse my ignorance but I have not a big familiarity with
> the CV paradigm (everything is a control value), any useful URLs that
>  handle his topic ?

Hard to say if its efficient. It's a tradeoff, it hadles some things very
well (ie. rapidy, unpredicatbly or continuously changing control values),
but it handles things that are mostly constant less efficiently than event
based systems.

I like it becasue it is easy to understand, model and process, and it has
good worst case performance.

I dont know of any resources, but the principal is very simple.
Frequencies are represented as an exponential scale of octaves, amplitudes
and time linearly. This covers everything and is very modular.

The obvious system for a sampler would be events for MIDI notes generating
sample buffer activity, and CV for internal parameter control. This should
get the best of both worlds. It is how SSM works, and that is very
efficient and versatile.

I am biased in favour of CV, so you should mayeb look for some oposing
arguments, I'm not aware of any ;)

- Steve