Fixed bpm.tapButton in common-controller-script.js

CHANGELOG

@@ -11,6 +11,7 @@
 * AutoDJ: Skip next track when both deck are playing lp:1399974 #2531
 * Tweak scratch parameters for Mixtrack Platinum #2028
 * Fix auto tempo going to infinity on Pioneer DDJ-SB2 #2559
+* Fix bpm.tapButton logic and reject missed & double taps #2594
 * Add controller mapping for Native Instruments Traktor Kontrol S2 MK3 #2348
 * Add controller mapping for Soundless joyMIDI #2425
 * Add controller mapping for Hercules DJControl Inpulse 300 #2465

res/controllers/common-controller-scripts.js

@@ -268,13 +268,13 @@ script.absoluteNonLinInverse = function(value, low, mid, high, min, max) {
     if (!max) {
         max = 127
     }
-    var center = (max - min) / 2
-    var result
+    var center = (max - min) / 2;
+    var result;
 
-    if (value == mid) {
-        return center
+    if (value === mid) {
+        return center;
     } else if (value < mid) {
-        result = (center / (mid - low)) * (value - low)
+        result = (center / (mid - low)) * (value - low);
     } else {
         result = center + (center / (high - mid)) * (value - mid)
     }
@@ -405,8 +405,9 @@ script.softStart = function(channel, control, value, status, group, factor) {
 bpm = function() {
 }
 
-bpm.tapTime = 0.0
-bpm.tap = []   // Tap sample values
+bpm.tapTime = 0.0;
+bpm.previousTapDelta = 0.0;
+bpm.tap = [];   // Tap sample values
 
 /* -------- ------------------------------------------------------
         bpm.tapButton
@@ -418,29 +419,51 @@ bpm.tap = []   // Tap sample values
    Output:  -
    -------- ------------------------------------------------------ */
 bpm.tapButton = function(deck) {
-    var now = new Date() / 1000   // Current time in seconds
-    var tapDelta = now - bpm.tapTime
-    bpm.tapTime = now
-    if (tapDelta > 2.0) { // reset if longer than two seconds between taps
-        bpm.tap = []
-        return
-    }
-    bpm.tap.push(60 / tapDelta)
-    if (bpm.tap.length > 8) bpm.tap.shift()  // Keep the last 8 samples for averaging
-    var sum = 0
-    for (i = 0; i < bpm.tap.length; i++) {
-        sum += bpm.tap[i]
+    var now = new Date() / 1000; // Current time in seconds
+    var tapDelta = now - bpm.tapTime;
+    bpm.tapTime = now;
+
+    // assign tapDelta in cases where the button has not been pressed previously
+    if (bpm.tap.length < 1) {
+        bpm.previousTapDelta = tapDelta;
+    }
+    // reset if longer than two seconds between taps
+    if (tapDelta > 2.0) {
+        bpm.tap = [];
+        return;
+    }
+    // reject occurences of accidental double or missed taps
+    // a tap is considered missed when the delta of this press is 80% longer than the previous one
+    // and a tap is considered double when the delta is shorter than 40% of the previous one.
+    // these numbers are just guesses that produced good results in practice
+    if ((tapDelta > bpm.previousTapDelta * 1.8)||(tapDelta < bpm.previousTapDelta * 0.6)) {
+        return;
+    }
+    bpm.previousTapDelta = tapDelta;
+    bpm.tap.push(60 / tapDelta);
+    // Keep the last 8 samples for averaging
+    if (bpm.tap.length > 8) bpm.tap.shift();
+    var sum = 0;
+    for (i=0; i<bpm.tap.length; i++) {
+        sum += bpm.tap[i];
     }
     var average = sum / bpm.tap.length
 
-    var fRateScale = average / engine.getValue("[Channel" + deck + "]", "bpm")
+    var group = "[Channel" + deck + "]";
+
+    // "bpm" was changed in 1.10 to reflect the *adjusted* bpm, but I presume it
+    // was supposed to return the tracks bpm (which it did before the change).
+    // "file_bpm" is supposed to return the set BPM of the loaded track of the
+    // channel.
+    var fRateScale = average/engine.getValue(group, "file_bpm");
 
     // Adjust the rate:
-    fRateScale = (fRateScale - 1.) / engine.getValue("[Channel" + deck + "]", "rateRange")
+    fRateScale = (fRateScale - 1.) / engine.getValue(group, "rateRange")
 
-    engine.setValue("[Channel" + deck + "]", "rate", fRateScale * engine.getValue("[Channel" + deck + "]", "rate_dir"))
-//     print("Script: BPM="+average+" setting to "+fRateScale);
-}
+    engine.setValue(
+        group, "rate",
+        fRateScale * engine.getValue(group, "rate_dir"));
+};
 
 // ----------------- Common regular expressions --------------------------
 script.samplerRegEx = /^\[Sampler(\d+)\]$/