allow sample offset modulation

fixes #51

package.json

@@ -1,6 +1,6 @@
 {
   "name": "SpessaSynth",
-  "version": "3.20.36.1",
+  "version": "3.20.36.2",
   "type": "module",
   "scripts": {
     "start": "node src/website/server/server.js"

src/spessasynth_lib/soundfont/read_sf2/generators.js

@@ -16,15 +16,15 @@ export const generatorTypes = {
     endAddrOffset: 1,                   // sample control - moves sample end point
     startloopAddrsOffset: 2,            // loop control - moves loop start point
     endloopAddrsOffset: 3,              // loop control - moves loop end point
-    startAddrsCoarseOffset: 4,          // sample control - moves sample start point in 32767 increments
+    startAddrsCoarseOffset: 4,          // sample control - moves sample start point in 32768 increments
     modLfoToPitch: 5,                   // pitch modulation - modulation lfo pitch modulation in cents
     vibLfoToPitch: 6,                   // pitch modulation - vibrato lfo pitch modulation in cents
     modEnvToPitch: 7,                   // pitch modulation - modulation envelope pitch modulation in cents
     initialFilterFc: 8,                 // filter - lowpass filter cutoff in cents
     initialFilterQ: 9,                  // filter - lowpass filter resonance
     modLfoToFilterFc: 10,               // filter modulation - modulation lfo lowpass filter cutoff in cents
     modEnvToFilterFc: 11,               // filter modulation - modulation envelope lowpass filter cutoff in cents
-    endAddrsCoarseOffset: 12,           // ample control - moves sample end point in 32767 increments
+    endAddrsCoarseOffset: 12,           // ample control - moves sample end point in 32768 increments
     modLfoToVolume: 13,                 // modulation lfo - volume (tremolo), where 100 = 10dB
     unused1: 14,
     chorusEffectsSend: 15,              // effect send - how much is sent to chorus 0 - 1000
@@ -57,12 +57,12 @@ export const generatorTypes = {
     reserved1: 42,
     keyRange: 43,                       // zone - key range for which preset / instrument zone is active
     velRange: 44,                       // zone - velocity range for which preset / instrument zone is active
-    startloopAddrsCoarseOffset: 45,     // ample control - moves sample loop start point in 32767 increments
+    startloopAddrsCoarseOffset: 45,     // sample control - moves sample loop start point in 32768 increments
     keyNum: 46,                         // zone - instrument only: always use this midi number (ignore what's pressed)
     velocity: 47,                       // zone - instrument only: always use this velocity (ignore what's pressed)
     initialAttenuation: 48,             // zone - allows turning down the volume, 10 = -1dB
     reserved2: 49,
-    endloopAddrsCoarseOffset: 50,       // ample control - moves sample loop end point in 32767 increments
+    endloopAddrsCoarseOffset: 50,       // sample control - moves sample loop end point in 32768 increments
     coarseTune: 51,                     // tune - pitch offset in semitones
     fineTune: 52,                       // tune - pitch offset in cents
     sampleID: 53,                       // sample - instrument zone only: which sample to use

src/spessasynth_lib/synthetizer/worklet_system/worklet_methods/note_on.js

@@ -73,6 +73,30 @@ export function noteOn(channel, midiNote, velocity, enableDebugging = false, sen
         }
         // compute all modulators
         computeModulators(voice, channelObject.midiControllers);
+        // modulate sample offsets (these are not real time)
+        const cursorStartOffset = voice.modulatedGenerators[generatorTypes.startAddrsOffset] + voice.modulatedGenerators[generatorTypes.startAddrsCoarseOffset] * 32768;
+        const endOffset = voice.modulatedGenerators[generatorTypes.endAddrOffset] + voice.modulatedGenerators[generatorTypes.endAddrsCoarseOffset] * 32768;
+        const loopStartOffset = voice.modulatedGenerators[generatorTypes.startloopAddrsOffset] + voice.modulatedGenerators[generatorTypes.startloopAddrsCoarseOffset] * 32768;
+        const loopEndOffset = voice.modulatedGenerators[generatorTypes.endloopAddrsOffset] + voice.modulatedGenerators[generatorTypes.endloopAddrsCoarseOffset] * 32768;
+        const sm = voice.sample;
+        // apply them
+        const clamp = num => Math.max(0, Math.min(sm.sampleData.length, num));
+        sm.cursor = clamp( sm.cursor + cursorStartOffset);
+        sm.end = clamp(sm.end + endOffset);
+        sm.loopStart = clamp(sm.loopStart + loopStartOffset);
+        sm.loopEnd = clamp(sm.loopEnd + loopEndOffset);
+        // swap loops if needed
+        if(sm.loopEnd < sm.loopStart)
+        {
+            const temp = sm.loopStart;
+            sm.loopStart = sm.loopEnd;
+            sm.loopEnd = temp;
+        }
+        if (sm.loopEnd - sm.loopStart < 1)
+        {
+            sm.loopingMode = 0;
+            sm.isLooping = false;
+        }
         // set the current attenuation to target,
         // as it's interpolated (we don't want 0 attenuation for even a split second)
         voice.volumeEnvelope.attenuation = voice.volumeEnvelope.attenuationTarget;

src/spessasynth_lib/synthetizer/worklet_system/worklet_utilities/worklet_voice.js

@@ -368,8 +368,8 @@ export function getWorkletVoices(channel,
             }
 
             // determine looping mode now. if the loop is too small, disable
-            let loopStart = (sampleAndGenerators.sample.sampleLoopStartIndex / 2) + (generators[generatorTypes.startloopAddrsOffset] + (generators[generatorTypes.startloopAddrsCoarseOffset] * 32768));
-            let loopEnd = (sampleAndGenerators.sample.sampleLoopEndIndex / 2) + (generators[generatorTypes.endloopAddrsOffset] + (generators[generatorTypes.endloopAddrsCoarseOffset] * 32768));
+            let loopStart = (sampleAndGenerators.sample.sampleLoopStartIndex / 2);
+            let loopEnd = (sampleAndGenerators.sample.sampleLoopEndIndex / 2);
             let loopingMode = generators[generatorTypes.sampleModes];
             const sampleLength = sampleAndGenerators.sample.getAudioData().length;
             // clamp loop
@@ -381,17 +381,18 @@ export function getWorkletVoices(channel,
                 loopingMode = 0;
             }
             /**
-             * create the worklet sample and calculate offsets
+             * create the worklet sample
+             * offsets are calculated at note on time (to allow for modulation of them)
              * @type {WorkletSample}
              */
             const workletSample = new WorkletSample(
                 sampleAndGenerators.sample.getAudioData(),
                 (sampleAndGenerators.sample.sampleRate / sampleRate) * Math.pow(2, sampleAndGenerators.sample.samplePitchCorrection / 1200), // cent tuning
-                generators[generatorTypes.startAddrsOffset] + (generators[generatorTypes.startAddrsCoarseOffset] * 32768),
+                0,
                 rootKey,
                 loopStart,
                 loopEnd,
-                Math.floor( sampleAndGenerators.sample.sampleData.length) - 1 + (generators[generatorTypes.endAddrOffset] + (generators[generatorTypes.endAddrsCoarseOffset] * 32768)),
+                Math.floor( sampleAndGenerators.sample.sampleData.length) - 1,
                 loopingMode
             )
             // velocity override

src/website/js/main/demo_main.js

@@ -425,7 +425,7 @@ demoInit(initLocale).then(() => {
             window.manager.sfError = e => {
                 loadingMessage.innerHTML = `Error parsing soundfont: <pre style='font-family: monospace; font-weight: bold'>${e}</pre>`;
                 changeIcon(getExclamationSvg(256));
-                console.log(e);
+                console.error(e);
             }
             loadingMessage.textContent = window.manager.localeManager.getLocaleString("locale.synthInit.startingSynthesizer");
             await window.manager.reloadSf(soundFontBuffer);