Volume envelope rework:

vol env now uses samples instead of seconds
code cleanup and optimizations for mod env
fixed decay times for both: now relative to sustain level like the spec says

package.json

@@ -1,6 +1,6 @@
 {
   "name": "SpessaSynth",
-  "version": "3.20.2",
+  "version": "3.20.3",
   "type": "module",
   "scripts": {
     "start": "node src/website/server/server.js"

src/spessasynth_lib/sequencer/worklet_sequencer/play.js

@@ -264,10 +264,8 @@ export function play(resetTime = false)
     }
     if(!this.sendMIDIMessages)
     {
-        const time = this.currentTime;
         this.playingNotes.forEach(n => {
-            const timeOffset = n.startTime - time;
-            this.synth.noteOn(n.channel, n.midiNote, n.velocity, false, true, currentTime + timeOffset);
+            this.synth.noteOn(n.channel, n.midiNote, n.velocity, false, true);
         });
     }
     this.setProcessHandler();

src/spessasynth_lib/sequencer/worklet_sequencer/process_event.js

@@ -36,8 +36,7 @@ export function _processEvent(event, trackIndex)
                 this.playingNotes.push({
                     midiNote: event.messageData[0],
                     channel: statusByteData.channel,
-                    velocity: velocity,
-                    startTime: this.currentTime
+                    velocity: velocity
                 });
             }
             else

src/spessasynth_lib/sequencer/worklet_sequencer/worklet_sequencer.js

@@ -60,8 +60,7 @@ class WorkletSequencer
          * @type {{
          *     midiNote: number,
          *     channel: number,
-         *     velocity: number,
-         *     startTime: number
+         *     velocity: number
          * }[]}
          */
         this.playingNotes = [];

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

@@ -1,7 +1,8 @@
 import { getWorkletVoices } from '../worklet_utilities/worklet_voice.js'
 import { generatorTypes } from '../../../soundfont/read_sf2/generators.js'
 import { computeModulators } from '../worklet_utilities/worklet_modulator.js'
-import { recalculateVolumeEnvelope } from '../worklet_utilities/volume_envelope.js'
+import { WorkletVolumeEnvelope } from '../worklet_utilities/volume_envelope.js'
+import { WorkletModulationEnvelope } from '../worklet_utilities/modulation_envelope.js'
 
 /**
  * Append the voices
@@ -72,7 +73,8 @@ export function noteOn(channel, midiNote, velocity, enableDebugging = false, sen
                     this.releaseVoice(v);
                     v.modulatedGenerators[generatorTypes.releaseVolEnv] = -7000; // make the release nearly instant
                     v.modulatedGenerators[generatorTypes.releaseModEnv] = -7000;
-                    recalculateVolumeEnvelope(v);
+                    WorkletVolumeEnvelope.recalculate(v);
+                    WorkletModulationEnvelope.recalculate(v);
                 }
             })
         }

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

@@ -2,12 +2,12 @@ import { generatorTypes } from '../../../soundfont/read_sf2/generators.js'
 import { absCentsToHz, decibelAttenuationToGain, timecentsToSeconds } from '../worklet_utilities/unit_converter.js'
 import { getLFOValue } from '../worklet_utilities/lfo.js'
 import { customControllers } from '../worklet_utilities/worklet_processor_channel.js'
-import { getModEnvValue } from '../worklet_utilities/modulation_envelope.js'
+import { WorkletModulationEnvelope } from '../worklet_utilities/modulation_envelope.js'
 import { getOscillatorData } from '../worklet_utilities/wavetable_oscillator.js'
 import { panVoice } from '../worklet_utilities/stereo_panner.js'
-import { applyVolumeEnvelope, recalculateVolumeEnvelope } from '../worklet_utilities/volume_envelope.js'
 import { applyLowpassFilter } from '../worklet_utilities/lowpass_filter.js'
 import { MIN_NOTE_LENGTH } from '../main_processor.js'
+import { WorkletVolumeEnvelope } from '../worklet_utilities/volume_envelope.js'
 
 
 const HALF_PI = Math.PI / 2;
@@ -36,10 +36,10 @@ export function renderVoice(
         // if not in release, check if the release time is
         if (currentTime >= voice.releaseStartTime)
         {
-            voice.releaseStartModEnv = voice.currentModEnvValue;
+
             voice.isInRelease = true;
-            recalculateVolumeEnvelope(voice);
-            voice.volumeEnvelope.currentReleaseGain = decibelAttenuationToGain(voice.volumeEnvelope.currentAttenuationDb);
+            WorkletVolumeEnvelope.startRelease(voice);
+            WorkletModulationEnvelope.startRelease(voice);
         }
     }
 
@@ -127,7 +127,7 @@ export function renderVoice(
     // mod env
     const modEnvPitchDepth = voice.modulatedGenerators[generatorTypes.modEnvToPitch];
     const modEnvFilterDepth = voice.modulatedGenerators[generatorTypes.modEnvToFilterFc];
-    const modEnv = getModEnvValue(voice, currentTime);
+    const modEnv = WorkletModulationEnvelope.getValue(voice, currentTime);
     // apply values
     lowpassCents += modEnv * modEnvFilterDepth;
     cents += modEnv * modEnvPitchDepth;
@@ -153,7 +153,7 @@ export function renderVoice(
     applyLowpassFilter(voice, bufferOut, lowpassCents);
 
     // volenv
-    applyVolumeEnvelope(voice, bufferOut, currentTime, modLfoCentibels, this.sampleTime, this.volumeEnvelopeSmoothingFactor);
+    WorkletVolumeEnvelope.apply(voice, bufferOut, modLfoCentibels, this.volumeEnvelopeSmoothingFactor);
 
     // pan the voice and write out
     voice.currentPan += (pan - voice.currentPan) * this.panSmoothingFactor; // smooth out pan to prevent clicking

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

@@ -7,7 +7,7 @@ import { modulatorCurveTypes } from '../../../soundfont/read_sf2/modulators.js'
  * modulation_envelope.js
  * purpose: calculates the modulation envelope for the given voice
  */
-const PEAK = 1;
+const MODENV_PEAK = 1;
 
 // 1000 should be precise enough
 const CONVEX_ATTACK = new Float32Array(1000);
@@ -16,58 +16,156 @@ for (let i = 0; i < CONVEX_ATTACK.length; i++) {
     CONVEX_ATTACK[i] = getModulatorCurveValue(0, modulatorCurveTypes.convex, i / 1000, 0);
 }
 
-/**
- * Calculates the current modulation envelope value for the given time and voice
- * @param voice {WorkletVoice} the voice we're working on
- * @param currentTime {number} in seconds
- * @returns {number} modenv value, from 0 to 1
- */
-export function getModEnvValue(voice, currentTime)
+export class WorkletModulationEnvelope
 {
-    // calculate env times
-    let attack = timecentsToSeconds(voice.modulatedGenerators[generatorTypes.attackModEnv]);
-    let decay = timecentsToSeconds(voice.modulatedGenerators[generatorTypes.decayModEnv] + ((60 - voice.midiNote) * voice.modulatedGenerators[generatorTypes.keyNumToModEnvDecay]));
-    let hold = timecentsToSeconds(voice.modulatedGenerators[generatorTypes.holdModEnv] + ((60 - voice.midiNote) * voice.modulatedGenerators[generatorTypes.keyNumToModEnvHold]));
+    /**
+     * The attack duration, in seconds
+     * @type {number}
+     */
+    attackDuration = 0;
+    /**
+     * The decay duration, in seconds
+     * @type {number}
+     */
+    decayDuration = 0;
 
-    // calculate absolute times
-    if(voice.isInRelease && voice.releaseStartTime < currentTime)
-    {
-        let release = timecentsToSeconds(voice.modulatedGenerators[generatorTypes.releaseModEnv]);
-        if(voice.modulatedGenerators[generatorTypes.releaseModEnv] < -7199)
-        {
-            // prevent lowpass bugs if release is instant
-            return voice.releaseStartModEnv;
-        }
-        return (1 - (currentTime - voice.releaseStartTime) / release) * voice.releaseStartModEnv;
-    }
+    /**
+     * The hold duration, in seconds
+     * @type {number}
+     */
+    holdDuration = 0;
 
-    let sustain = 1 - (voice.modulatedGenerators[generatorTypes.sustainModEnv] / 1000);
-    let delayEnd  = timecentsToSeconds(voice.modulatedGenerators[generatorTypes.delayModEnv]) + voice.startTime;
-    let attackEnd = attack + delayEnd;
-    let holdEnd = hold + attackEnd;
-    let decayEnd = decay + holdEnd;
+    /**
+     * Release duration, in seconds
+     * @type {number}
+     */
+    releaseDuration = 0;
 
-    let modEnvVal
-    if(currentTime < delayEnd)
-    {
-        modEnvVal = 0; // delay
-    }
-    else if(currentTime < attackEnd)
-    {
-        modEnvVal = CONVEX_ATTACK[~~((1 - (attackEnd - currentTime) / attack) * 1000)]; // convex attack
-    }
-    else if(currentTime < holdEnd)
+    /**
+     * The sustain level 0-1
+     * @type {number}
+     */
+    sustainLevel = 0;
+
+    /**
+     * Delay phase end time in seconds, absolute (audio context time)
+     * @type {number}
+     */
+    delayEnd = 0;
+    /**
+     * Attack phase end time in seconds, absolute (audio context time)
+     * @type {number}
+     */
+    attackEnd = 0;
+    /**
+     * Hold phase end time in seconds, absolute (audio context time)
+     * @type {number}
+     */
+    holdEnd = 0;
+    /**
+     * Decay phase end time in seconds, absolute (audio context time)
+     * @type {number}
+     */
+    decayEnd = 0;
+
+    /**
+     * The level of the envelope when the release phase starts
+     * @type {number}
+     */
+    releaseStartLevel = 0;
+
+    /**
+     * The current modulation envelope value
+     * @type {number}
+     */
+    currentValue = 0;
+
+    /**
+     * Starts the release phase in the envelope
+     * @param voice {WorkletVoice} the voice this envelope belongs to
+     */
+    static startRelease(voice)
     {
-        modEnvVal = PEAK; // peak
+        voice.modulationEnvelope.releaseStartLevel = voice.modulationEnvelope.currentValue;
+        WorkletModulationEnvelope.recalculate(voice);
     }
-    else if(currentTime < decayEnd)
+
+    /**
+     * @param voice {WorkletVoice} the voice to recalculate
+     */
+    static recalculate(voice)
     {
-        modEnvVal = (1 - (decayEnd - currentTime) / decay) * (sustain - PEAK) + PEAK; // decay
+        const env = voice.modulationEnvelope;
+
+        env.sustainLevel = 1 - (voice.modulatedGenerators[generatorTypes.sustainModEnv] / 1000);
+
+        env.attackDuration = timecentsToSeconds(voice.modulatedGenerators[generatorTypes.attackModEnv]);
+
+        const decayKeyExcursionCents = ((60 - voice.midiNote) * voice.modulatedGenerators[generatorTypes.keyNumToModEnvDecay]);
+        const decayTime = timecentsToSeconds(voice.modulatedGenerators[generatorTypes.decayModEnv] + decayKeyExcursionCents);
+        // according to the specification, the decay time is the time it takes to reach 0% from 100%.
+        // calculate the time to reach actual sustain level
+        // for example, sustain 0.6 will be 0.4 of the decay time
+        env.decayDuration = decayTime * (1 - env.sustainLevel);
+
+        const holdKeyExcursionCents = ((60 - voice.midiNote) * voice.modulatedGenerators[generatorTypes.keyNumToModEnvHold]);
+        env.holdDuration = timecentsToSeconds(holdKeyExcursionCents + voice.modulatedGenerators[generatorTypes.holdModEnv]);
+
+        const releaseTime = timecentsToSeconds(voice.modulatedGenerators[generatorTypes.releaseVolEnv]);
+        // release time is from the full level to 0%
+        // to get the actual time, multiply by the release start level
+        env.releaseDuration = releaseTime * env.releaseStartLevel;
+
+        env.delayEnd = voice.startTime + timecentsToSeconds(voice.modulatedGenerators[generatorTypes.delayModEnv]);
+        env.attackEnd = env.delayEnd + env.attackDuration;
+        env.holdEnd = env.attackEnd + env.holdDuration;
+        env.decayEnd = env.holdEnd + env.decayDuration;
     }
-    else
+
+    /**
+     * FIXME: GeneralUserGS 808 toms sound incorrect
+     * Calculates the current modulation envelope value for the given time and voice
+     * @param voice {WorkletVoice} the voice we're working on
+     * @param currentTime {number} in seconds
+     * @returns {number} modenv value, from 0 to 1
+     */
+    static getValue(voice, currentTime)
     {
-        modEnvVal = sustain; // sustain
+        const env = voice.modulationEnvelope;
+        if(voice.isInRelease)
+        {
+            if(voice.modulatedGenerators[generatorTypes.releaseModEnv] < -7199)
+            {
+                // prevent lowpass bugs if release is instant
+                return env.releaseStartLevel;
+            }
+            return Math.max(0, (1 - (currentTime - voice.releaseStartTime) / env.releaseDuration) * env.releaseStartLevel);
+        }
+
+        if(currentTime < env.delayEnd)
+        {
+            env.currentValue = 0; // delay
+        }
+        else if(currentTime < env.attackEnd)
+        {
+            // modulation envelope uses convex curve for attack
+            env.currentValue = CONVEX_ATTACK[~~((1 - (env.attackEnd - currentTime) / env.attackDuration) * 1000)];
+        }
+        else if(currentTime < env.holdEnd)
+        {
+            // hold: stay at 1
+            env.currentValue = MODENV_PEAK;
+        }
+        else if(currentTime < env.decayEnd)
+        {
+            // decay: linear ramp from 1 to sustain level
+            env.currentValue = (1 - (env.decayEnd - currentTime) / env.decayDuration) * (env.sustainLevel - MODENV_PEAK) + MODENV_PEAK;
+        }
+        else
+        {
+            // sustain: stay at sustain level
+            env.currentValue = env.sustainLevel;
+        }
+        return env.currentValue;
     }
-    voice.currentModEnvValue = modEnvVal;
-    return modEnvVal;
 }

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

@@ -1,5 +1,5 @@
-export const WORKLET_SYSTEM_REVERB_DIVIDER = 500;
-export const WORKLET_SYSTEM_CHORUS_DIVIDER = 500;
+export const WORKLET_SYSTEM_REVERB_DIVIDER = 800;
+export const WORKLET_SYSTEM_CHORUS_DIVIDER = 800;
 /**
  * stereo_panner.js
  * purpose: pans a given voice out to the stereo output and to the effects' outputs