Modfile fixes (#6)

- REMOVED: modules that do not play correctly yet from the playlist
- FIXED: channel.cmd wasn't reset after loading a new mod
- FIXED: if channel.length == 2 length seems to be ignored by players (Agony)
- FIXED: very old mod files with 15 samples had wrong offsets for patterns/positions (Silkworm)
- FIXED: oops, fixed channel swapping in compatibility mode

- ADDED: build instructions
- ADDED: note about Xbox One special case

.gitignore

@@ -1 +1,2 @@
 node_modules
+dist

README.md

@@ -42,6 +42,14 @@ ModPlayer JS makes use of the following piece of software:
 
 I also heavily used [MilkyTracker](https://milkytracker.titandemo.org/) and [webaudio-mod-player](https://mod.haxor.fi/) - which plays lot of module formats with high fidelity - to track down some timing bugs.
 
+# Building modplayer-js
+
+modplayer-js only needs a webserver, which can be installed by typing `npm install` and then `http-server`.
+
+If you want to use modplayer-js on an Xbox One, you'll also need to type `npm run build`: this will generate an ES5 version of the `mod-processor.js` file.
+
+This is because for some unknown reason, on Xbox One Edge, the audioworklet polyfill refuses to execute ES6 code.
+
 # Module background
 
 Modules are like MIDI files but with custom sound samples instead of builtin synth files.

js/main.js

@@ -1,23 +1,23 @@
 var moduleList = [
     { file: 'https://api.modarchive.org/downloads.php?moduleid=91286#faggots_universe.mod', author: 'Deelite' },
-    { file: 'https://api.modarchive.org/downloads.php?moduleid=168739#neurodancer_-_quasar.mod', author: 'Neurodancer' },
-    { file: 'https://api.modarchive.org/downloads.php?moduleid=183672#tax_haven_dry_hump.mod', author: 'Curt Cool' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=182057#h0ffman_-_drop_the_panic.mod', author: 'h0ffman' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=168122#prodigy_-_downtown.mod', author: 'prodigy of oops' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=172266#hoffman_-_the_hunter.mod', author: 'h0ffman' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=65280#variations.mod', author: 'jogeir-liljedahl' },
-    { file: 'https://api.modarchive.org/downloads.php?moduleid=166686#wiklund_-_bonfire.mod', author: 'Wiklund' },
+    // { file: 'https://api.modarchive.org/downloads.php?moduleid=166686#wiklund_-_bonfire.mod', author: 'Wiklund' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=55058#pinball_illusions.mod', author: 'Olof Gustafsson' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=167668#vinnie_-_sweet_dreams.mod', author: 'vinnie/spaceballs' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=172271#subi-king_of_boggle.mod', author: 'Subi/DESiRE' },
-    { file: 'https://api.modarchive.org/downloads.php?moduleid=171416#bass-1107.mod', author: 'Noiseless (cm/ao)' },
+    // { file: 'https://api.modarchive.org/downloads.php?moduleid=171416#bass-1107.mod', author: 'Noiseless (cm/ao)' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=168110#punnik_-_drum_bass.mod', author: 'punnik' },
-    { file: 'https://api.modarchive.org/downloads.php?moduleid=171616#dan_-_childs_philozophy.mod', author: 'dan / picco' },
+    // { file: 'https://api.modarchive.org/downloads.php?moduleid=171616#dan_-_childs_philozophy.mod', author: 'dan / picco' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=119303#boesendorfer_p_s_s.mod', author: 'romeoknight' },
-    { file: 'https://api.modarchive.org/downloads.php?moduleid=170637#ghost_in_the_cli.mod', author: 'h0ffman' },
-    { file: 'https://api.modarchive.org/downloads.php?moduleid=158057#alf_-_no-mercy.mod', author: 'alf/vtl' },
+    // { file: 'https://api.modarchive.org/downloads.php?moduleid=170637#ghost_in_the_cli.mod', author: 'h0ffman' },
+    // { file: 'https://api.modarchive.org/downloads.php?moduleid=158057#alf_-_no-mercy.mod', author: 'alf/vtl' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=105709#trans_atlantic.mod', author: 'Lizardking'},
     { file: 'https://api.modarchive.org/downloads.php?moduleid=124303#agony_intro.mod', author: 'Tim Wright' },
+    { file: 'https://api.modarchive.org/downloads.php?moduleid=168739#neurodancer_-_quasar.mod', author: 'Neurodancer' },
+    { file: 'https://api.modarchive.org/downloads.php?moduleid=183672#tax_haven_dry_hump.mod', author: 'Curt Cool' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=98051#big_time_sensuality.mod', author: 'ISO/Axis Group' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=34568#CANNONFO.MOD', author: 'John Hare' },
     { file: 'https://api.modarchive.org/downloads.php?moduleid=68835#desert_strike.mod', author: 'Jason Whitley' },

js/mod-processor.js

@@ -46,7 +46,6 @@ class PTModuleProcessor extends AudioWorkletProcessor{
         // pattern data always starts at offset 1084
         super();
         this.port.onmessage = this.handleMessage.bind(this);
-        this.patternOffset = 1084;
         this.patternLength = 1024;
     }
 
@@ -195,7 +194,8 @@ class PTModuleProcessor extends AudioWorkletProcessor{
                 vspeed: 0,
                 vpos: 0,
                 loopInitiated: false,
-                id: i
+                id: i,
+                cmd: 0
             };
             if (!this.channels[i]) {
                 this.channels[i] = channel;
@@ -240,6 +240,12 @@ class PTModuleProcessor extends AudioWorkletProcessor{
         // but we stick to good old ST/NT modules
         const str = BinUtils.readAscii(this.buffer, 4, 1080);
         this.maxSamples = str.match("M.K.") ? 31 : 15;
+
+        if (this.maxSamples === 15) {
+            this.patternOffset = 1080 - 480;
+        } else {
+            this.patternOffset = 1084;
+        }
     }
 
     /**
@@ -278,11 +284,12 @@ class PTModuleProcessor extends AudioWorkletProcessor{
             this.tick();
             for (let chan = 0; chan < this.channels.length; ++chan) {
                 const channel = this.channels[chan];
-                const buffer = this.audioWorkletSupport ? outputs[chan][0] : outputs[0][outputChannel];
                 // select left/right output depending on module channel:
                 // voices 0,3 go to left channel, 1,2 go to right channel
                 outputChannel = outputChannel ^ (chan & 1);
 
+                const buffer = this.audioWorkletSupport ? outputs[chan][0] : outputs[0][outputChannel];
+
                 // TODO: check that no effect can be applied without a note
                 // otherwise that will have to be moved outside this loop
                 if (this.newTick && channel.cmd) {
@@ -472,6 +479,10 @@ class PTModuleProcessor extends AudioWorkletProcessor{
             // Existing mod players seem to play a sample only once if repeatLength is set to 2
             if (sample.repeatLength === 2) {
                 sample.repeatLength = 0;
+                // some modules seems to skip the first two bytes for length
+                if (sample.length === 2) {
+                    sample.length = 0;
+                }
             }
 
             if (sample.repeatLength > sample.length) {
@@ -487,7 +498,8 @@ class PTModuleProcessor extends AudioWorkletProcessor{
 
     getPatternData() {
         // pattern data always starts at offset 950
-        const uint8buffer = new Uint8Array(this.buffer, 950);
+        const offset = this.maxSamples === 15 ? 470 : 950;
+        const uint8buffer = new Uint8Array(this.buffer, offset);
         this.songLength = uint8buffer[0];
         let position = 2;
         let max = 0;
@@ -515,7 +527,8 @@ class PTModuleProcessor extends AudioWorkletProcessor{
         for (let i = 0; i < this.samples.length; ++i) {
             const length = this.samples[i].length,
                 data = new Float32Array(length),
-                pcm = new Int8Array(this.buffer, offset, length);
+                maxLength = (offset + length) > this.buffer.byteLength ? this.buffer.byteLength - offset : length,
+                pcm =  new Int8Array(this.buffer, offset, maxLength);
 
             // convert 8bit pcm format to webaudio format
             for (let j = 0; j < length; ++j) {
@@ -524,7 +537,7 @@ class PTModuleProcessor extends AudioWorkletProcessor{
 
             this.samples[i].data = data;
 
-            offset += length;
+            offset += maxLength;
         }
     }