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

[<be...@ga...>]

Yes the clicks are coming from the missing release envelopes.
Adding release envelopes will make them go away but for implementing
envelopes we need the event system implemented first.
The event system will not only make possible envelopes but 
release triggered samples, layering, pitch modulation and all the other
stuff you need for perfect  GIG playback.
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.
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 ?
Since pitch envelopes are made of "deltas" in theory one could simply
add up the deltas when events come in.
eg ... if there is only one envelope then the events should overwrite
the current pitch delta but if you want to mix two or more envelopes
then deltas should added up (basically you could calculate
the delta of the delta between events and simply add up that to the
current delta. That way AFAIK it should work with one single and multiple
 active envelopes. 
Am I missing something ? :-)

cheers,
Benno
http://www.linuxsampler.org



Scrive Mark Knecht <mar...@co...>:

> Hi,
>    I sat for a while this afternoon and investigated the clicks and pops
> that we are all getting out of LS. As far as I can tell they are (in my
> cases) coming from the lack of release samples and not from the attack
> envelope as I had hypothesized  earlier.
> 
>    To look at this I first set up Pro Tools and recorded audio coming
> from both samplers. After that I measured the latency between the MIDI
> event in Pro Tools and when audio was recorded from that event in LS.
> This is much easier to find based on going from quiet to loud visually.
> 
>    Then knowing that latency number I used the Pro Tools scrubber and
> searched for clicks and pops in the LS audio stream. When I found them,
> I looked for note off events in the MIDI stream and found that they were
> always the same latency value ahead of the click and pop. I think this
> pretty clearly demonstrates the problem comes from the end of the sample
> and not the beginning.


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