Re: [Linuxsampler-devel] envelopes, events, Re: LS click/pop investigation

[ian e. <de...@cu...>]

On Tue, 2003-12-30 at 04:26, be...@ga... wrote:
> The problem with the event system  is that we need to figure out a 
> good tradeoff between flexibility and speed.
> 
> David (Olofson), what do you suggest ? Using an event system similar to the
> one you use in audiality ?
> For performance reasons I'd opt for a system that uses only linear
> segments for both volume and pitch enveloping.
> exp curves and other kind of envelopes can be easily simulated by
> using a serie of linear segments.

i think you would probably find this to be more expensive than having
log/exp curves. to create the traditional log style envelopes is
actually very easy, and can be done with a modified one pole (no zero)
lowpass filter. that just requires one coefficient calculation for the
whole curve, rather than doing a whole load of calculations for each
linear segment.

> Keep in mind it must for example handle following tasks:
> assume there is a pitch envelope running (composed of linear segments).
> Now the user operates the pitchbender.
> The real time event is timestamped and delayed till the next audio fragment
>  gets processed. If there is already an envelope running the pitchbender
>  needs to "add" his own pitch to the current one possibly using an event.
> for example if we want two pitch envelopes modulating the same sample
>  what's the best way to do it ?

just add the two (or more) modulating sources scaled by the mod depths
to get the final mod amount.

ian