Re: [Linuxsampler-devel] voice stealing

[Marek P. <ma...@na...>]

Hi Vladimir & all,

just wanted to ask, is there any reason why linuxsampler can't have just
one voice per note? For example suppose i've got a huge lib loaded with
long samples that need to be streamed from disk,  currently AFAIK if i
press a note and then press the same note again, i end up with 2
streams. But if you imagine an instrument such as a piano, a hammer
which hits a string at a given time is going to completely dampen the
previous string resonance at that time while causing a new resonance.
That seems like dismissing the old stream completely at the time i hit a
note and starting a new one hence you end up with a nice 1 voice per
note optimisation. Perhaps i'm wrong, just my imagination...

Marek

On Sun, 2004-02-08 at 19:50, Vladimir Senkov wrote:
> Hi Everybody,
> 
> I've been thinking about note stealing or as i'd like to call it "voice 
> stealing".
> So far the following comes to mind:
> 1) When number of voices reaches max there will not be any time to 
> release them, so we have to start releasing them earlier. I'm 
> introducing AUDIO_VOICES_THRESHOLD. It should be set to be a certain 
> percentage of MAX_AUDIO_VOICES depending on how long the release phase 
> is. If it's set to the same value as MAX_AUDIO_VOICES or higher, then 
> voice stealing will be disabled.
> 2) When number of voices reaches the threshold and a new key is pressed, 
> ls will try the following:
>  a) locate voices on that same key and release all but the last one of them
>  b) if that didn't yeld any results, go thru all keys and try same
>  c) if that didn't work either, try same as above but be more aggressive 
> i.e. free the last voice as well.
> 
> What do you guys think? Any better ideas?
> I've been playing around with it and it seems to work OK. With max 
> voices set to 64 i've set the threshold to 48 and it seems to take care 
> of most situations. Depending on how long the release phase is, it may 
> need to be set to something lower (or max voices will have to be 
> increased). At some point we could add a clever algorithm to calculate 
> the threshold automatically based on how long the release phase is 
> (average release time for all samples?)
> 
> I'm including a patch against latest CVS. This patch also includes some 
> command line and EG changes. Christian will likely review those (but not 
> the voice stealing part) next weekend and it might make it in some shape 
> of form into the CVS, so please give it some testing also, if you have 
> time. If you have trouble with voice stealing and just want to play 
> around with the EG you can turn off voice stealing by setting 
> AUDIO_VOICES_THRESHOLD to be same as MAX_AUDIO_VOICES in audiothread.h.
> 
> Regards,
> Vladimir.
>