OPL4 WIP new Volume algorithm

Author: ppeccin

src/main/msx/audio/OPL4Audio.js

@@ -89,10 +89,11 @@ wmsx.OPL4Audio = function(pName, cart) {
 
     var audioSocket, audioSignal;
 
-    var VOLUME = 0.65 * (7 / 24 / 4096);      // X channels, samples -4096 .. +4096
+    var VOLUME = 0.65 * (7 / 24 / 32768);     // 24 channels, samples -32768 .. +32768
     var SAMPLE_RATE = 44100;                  // Main CPU clock / 81.2734693877551 = 44100 Hz
     var CLOCK = 49780;                        // Main CPU clock / 72 = 49780 Hz
 
+
     // Savestate  -------------------------------------------
 
     this.saveState = function() {

src/main/msx/audio/OPL4AudioWave.js

@@ -16,6 +16,7 @@ wmsx.OPL4AudioWave = function(opl4) {
         rateDecayDurTable = tabs.getRateDecayDurations();
         envAttackCurve = tabs.getEnvAttackCurve();
         panpotValues = tabs.getPanPotValues();
+        volumeTable = tabs.getVolumeTable();
     }
 
     this.connect = function(machine) {
@@ -61,17 +62,19 @@ wmsx.OPL4AudioWave = function(opl4) {
         wmsx.Util.arrayFill(dl, 0);
         wmsx.Util.arrayFill(d2r, 0);
         wmsx.Util.arrayFill(rr, 0);
-        wmsx.Util.arrayFill(volume, 0x7f);
         wmsx.Util.arrayFill(am, 0);
         wmsx.Util.arrayFill(vib, 0);
         wmsx.Util.arrayFill(rc, 0);
+        wmsx.Util.arrayFill(volume, 0x7f);
+        wmsx.Util.arrayFill(panpotL, 0);
+        wmsx.Util.arrayFill(panpotR, 0);
 
         // Dynamic values
 
         wmsx.Util.arrayFill(amAtt, 0);
-        wmsx.Util.arrayFill(envAtt, 0x100 << 4);
-        wmsx.Util.arrayFill(totalAttL, 0x100 << 4);
-        wmsx.Util.arrayFill(totalAttR, 0x100 << 4);
+        wmsx.Util.arrayFill(envAtt, 256);
+        wmsx.Util.arrayFill(totalAttL, 1024);
+        wmsx.Util.arrayFill(totalAttR, 1024);
         wmsx.Util.arrayFill(envStep, IDLE);
         wmsx.Util.arrayFill(envStepLevelDur, 0);
         wmsx.Util.arrayFill(envStepLevelIncClock, 0);
@@ -135,11 +138,11 @@ wmsx.OPL4AudioWave = function(opl4) {
 
             if (delta > 0) {
                 sample = advanceSample(cha, delta);
-                sampleL += expTable[sample + totalAttL[cha]];
-                sampleR += expTable[sample + totalAttR[cha]];
+                sampleL += sample * volumeTable[totalAttL[cha]];
+                sampleR += sample * volumeTable[totalAttR[cha]];
             } else {
-                sampleL += expTable[sampleValue[cha] + totalAttL[cha]];
-                sampleR += expTable[sampleValue[cha] + totalAttR[cha]];
+                sampleL += sampleValue[cha] * volumeTable[totalAttL[cha]];
+                sampleR += sampleValue[cha] * volumeTable[totalAttR[cha]];
             }
 
             // if (delta > 0) sampleL += advanceSample(cha, delta); else sampleL += sampleValue[cha];
@@ -319,15 +322,15 @@ wmsx.OPL4AudioWave = function(opl4) {
     function startSample(cha) {
         samplePos[cha] = 0;
         phaseCounter[cha] = 0;
-        return updateSampleValue12bitsLog(cha);
+        return updateSampleValue16bits(cha);
     }
 
     function advanceSample(cha, quant) {
         var newPos = samplePos[cha] + quant;
         samplePos[cha] = newPos > endPosition[cha]
             ? loopPosition[cha] + (newPos - endPosition[cha]) - 1
             : newPos;
-        return updateSampleValue12bitsLog(cha);
+        return updateSampleValue16bits(cha);
     }
 
     function updateSampleValue12bitsLog(cha) {
@@ -492,8 +495,8 @@ wmsx.OPL4AudioWave = function(opl4) {
     }
 
     function updateTotalAttenuation(cha) {
-        totalAttL[cha] = amAtt[cha] + (envAtt[cha] << 4) + (volume[cha] << 4) + (panpotL[cha] << 7);
-        totalAttR[cha] = amAtt[cha] + (envAtt[cha] << 4) + (volume[cha] << 4) + (panpotR[cha] << 7);
+        totalAttL[cha] = amAtt[cha] + (envAtt[cha] << 0) + (volume[cha] << 0) + (panpotL[cha] << 3);
+        totalAttR[cha] = amAtt[cha] + (envAtt[cha] << 0) + (volume[cha] << 0) + (panpotR[cha] << 3);
     }
 
 
@@ -559,7 +562,7 @@ wmsx.OPL4AudioWave = function(opl4) {
 
     // Pre calculated tables, factors, values
 
-    var linearTable, expTable, vibValues, rateAttackDurTable, rateDecayDurTable, envAttackCurve, panpotValues;
+    var volumeTable, linearTable, expTable, vibValues, rateAttackDurTable, rateDecayDurTable, envAttackCurve, panpotValues;
     var sampleResult = [ 0, 0 ];
 
 

src/main/msx/audio/OPL4WaveTables.js

@@ -68,6 +68,14 @@ wmsx.OPL4WaveTables = function() {
         return this.PANPOT_VALUES;
     };
 
+    this.getVolumeTable = function() {
+        var v = new Array(1025);
+        for (var i = 0; i < 1024; ++i) v[i] = Math.pow(10, -0.375 * i / 20);
+        v[1024] = 0;
+        return v;
+    };
+
+
     this.VIB_VALUES = [
         [ 0, 0, 0, 0, 0,  0,  0,  0 ],      // According to fNum >> 6 (one line for each value)
         [ 0, 0, 1, 0, 0,  0, -1,  0 ],      // Half these values must be added to fNum BEFORE multi
@@ -121,7 +129,6 @@ wmsx.OPL4WaveTables = function() {
         // -3 .. -18 dB. Min = -96 dB
         [ 0, 1, 2, 3, 4, 5, 6, 32, 32,   0, 0, 0, 0, 0, 0, 0 ],     // L
         [ 0, 0, 0, 0, 0, 0, 0,   0, 32, 32, 6, 5, 4, 3, 2, 1 ]      // R
-    ]
-
+    ];
 
 };