Rapture/Dimension Voice Stealing Algorithm

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b rock
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2006/04/17 08:57:13 (permalink)

Rapture/Dimension Voice Stealing Algorithm

OK, so the "Expression Engine" has a low limt in polyphony of 0 voices: one voice in monophonic legato mode. Polyphony of one sets it in monophonic, 16 voices is the default, and there's an infinite number of voices as an upper limit. These polyphonic limits are set per-Element, so dynamic allocation of voices in multitimbral mode isn't a concern. So, why even bring this up? I use polyphony limits as a performance device, and to impart some realism into emulating real-world instruments.

So, the voice-stealing algo is straightforward in the mono modes: new note takes priority over the last note played. At two voices, a low-note priority seems to take over. Beyond 3 or 4 voices, I have difficulty tracking the priority anymore. I guess that I could get all scientific here with some solid clips and listening tests (I'm winging this live), but it's be interesting to know the brief overview of the mathematics and decision-making behind the process.

Besides, I'm also wondering if I might be the lone soldier in this campaign. I know that this can be overridden (prioritized) in .sfz editing, so my real question would concern the default voice-stealing that occurs at polyphony limits (without any outside intervention).
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    René
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    RE: Rapture/Dimension Voice Stealing Algorithm 2006/04/17 10:03:57 (permalink)
    Without resorting to sfz magic, the voice-stealing algorithm in both Dimension Pro and Rapture is basically as you described (time precedence).

    There're a few 'special cases', and that's why I say 'basically'.
    The special cases will apply when multiple voices are in place, some of those are already in release stage even when they're newer than others, older but still in sustain stage. There's also the psychoacoustic principle of "precedence of the sounds at the unison", and the "precedence of the lowest note".

    And also those voices which are used by release triggers (as in DP "rt" pianos). And then the fact that each element has its own voice count and polyphony stealing independence. And a couple of others that I cannot really disclose, but are cool



    -René
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    b rock
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    RE: Rapture/Dimension Voice Stealing Algorithm 2006/04/17 12:18:38 (permalink)
    Thanks for the quick answer, Rene. As always, accurate & complete enough to determine the answers to what may come up later on in practice.
    I've also come to expect those fine details that I may have not considered, followed by the inevitable teaser thrown in to drive me crazy.

    Thanks for that, too. I think ...
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    Dan_E10
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    RE: Rapture/Dimension Voice Stealing Algorithm 2008/05/27 08:49:18 (permalink)
    Anyone know if there's a way to set up monophonic legato mode in an sfz file? I have an sfz where I assign different .wav's so they can share the same envelopes and filter settings. However I noticed that if I set that element's number of voices to 0, only one of the .wav's makes it through. I have to raise the polyphony up for that element to be equal to or greater than the number of .wav's. It still doesn't respond the same way as if I had assigned each of the .wav's to its own element and set polyphony to 0 for each, i.e. no legato mode.
    thanks,
    Dan
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    Fog
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    RE: Rapture/Dimension Voice Stealing Algorithm 2008/05/27 12:37:32 (permalink)
    Hi René, it's off topic.. but would there ever be plans to include RX2 format into at least DP or the SFZ format itself?

    it's something that would make it far more usable for me (and helps me save a heap of drive space). I mean in the sense of multi-samples , say a piano etc.

    I did convert some samples to RX2 and edited the SFZ accordingly, which when I called the patch, it didn't like. I know the rx2 format only goes up to 24 bit currently, but even still.
    post edited by Fog - 2008/05/27 12:41:51
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