Fixed adjustPreset in player, to work around two pathological cases i… #104

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opened 2025-10-14 15:47:53 -06:00 by navan · 0 comments

navan commented

2025-10-14 15:47:53 -06:00

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Originally created by @SAKryukov on 8/20/2017

Fixed adjustPreset in player, to work around two pathological cases in instrument .js files (presets)::

Some files have zones with zone.keyRangeLow > zone.keyRangeHigh; they are not used anyway and can be removed; this is a big performance improved, as, in some files, they reduce number of zones by order of magnitude
All files have zones with 1-semiton gaps, such as 0..29, 29..36, and so on. This is methodically totally wrong, but works with integer number of semitones. Microtones can be fractional; if, for example, the pitch values is 29.1, the zone will never be found, and its fallback is a zone at index 0. It produces intolerably bad quality of sound.

The fix is in just one function, just few line; it does not change sounds with integer number of semitones:

this.adjustPreset = function (audioContext, preset) {
    const fixedZones = [];
    for (let zone of preset.zones) {
        if (zone.keyRangeLow > zone.keyRangeHigh) continue; // pathological case, not used anyway
        fixedZones.push(zone);
        this.adjustZone(audioContext, zone);
    } //loop preset.zones
    preset.zones = fixedZones;
    // removing 1-semitone gaps between zones; important for microtones:
    for (let index = 1; index < preset.zones.length; ++index)
        preset.zones[index].keyRangeLow = preset.zones[index - 1].keyRangeHigh;
};

It fully fixes issue 8 in non-obtrusive comprehensive way.

*Originally created by @SAKryukov on 8/20/2017* Fixed adjustPreset in player, to work around two pathological cases in instrument .js files (presets):: 1) Some files have zones with zone.keyRangeLow > zone.keyRangeHigh; they are not used anyway and can be removed; this is a big performance improved, as, in some files, they reduce number of zones by order of magnitude 2) ***All*** files have zones with 1-semiton gaps, such as 0..29, 29..36, and so on. This is methodically totally wrong, but works with integer number of semitones. Microtones can be fractional; if, for example, the pitch values is 29.1, the zone will never be found, and its fallback is a zone at index 0. It produces intolerably bad quality of sound. The fix is in just one function, just few line; it does not change sounds with integer number of semitones: ``` this.adjustPreset = function (audioContext, preset) { const fixedZones = []; for (let zone of preset.zones) { if (zone.keyRangeLow > zone.keyRangeHigh) continue; // pathological case, not used anyway fixedZones.push(zone); this.adjustZone(audioContext, zone); } //loop preset.zones preset.zones = fixedZones; // removing 1-semitone gaps between zones; important for microtones: for (let index = 1; index < preset.zones.length; ++index) preset.zones[index].keyRangeLow = preset.zones[index - 1].keyRangeHigh; }; ``` It fully fixes [issue 8](https://github.com/surikov/webaudiofont/issues/8) in non-obtrusive comprehensive way.

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Reference: github/webaudiofont#104

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