new "getSoundAttribute" reporter primitive

HISTORY.md

@@ -16,6 +16,7 @@
     * selectors for changing and querying "draggable" and "rotation style" settings
     * new sound + music "volume" feature + blocks
     * new sound + music stereo "panning" feature + blocks
+    * new sound attribute getter reporter
     * new "play frequency" commands in the Sounds category
     * added "neg" selector to monadic function reporter in "Operators" category
     * added "log2" selector to monadic function reporter in "Operators" category
@@ -57,6 +58,9 @@
     * German
     * French
 
+### 2019-04-08
+* Blocks, Objects, Threads: new "getSoundAttribute" reporter primitive
+
 ### 2019-04-05
 * Objects: eliminated "clicks" when playing music notes
 * Objects: eliminated "clicks" when playing a frequency

snap.html

@@ -6,9 +6,9 @@
         <link rel="shortcut icon" href="src/favicon.ico">
         <script type="text/javascript" src="src/morphic.js?version=2019-02-07"></script>
         <script type="text/javascript" src="src/widgets.js?version=2019-04-05"></script>
-        <script type="text/javascript" src="src/blocks.js?version=2019-04-04"></script>
+        <script type="text/javascript" src="src/blocks.js?version=2019-04-08"></script>
-        <script type="text/javascript" src="src/threads.js?version=2019-04-07"></script>
+        <script type="text/javascript" src="src/threads.js?version=2019-04-08"></script>
-        <script type="text/javascript" src="src/objects.js?version=2019-04-05"></script>
+        <script type="text/javascript" src="src/objects.js?version=2019-04-08"></script>
         <script type="text/javascript" src="src/gui.js?version=2019-03-25"></script>
         <script type="text/javascript" src="src/paint.js?version=2019-02-22"></script>
         <script type="text/javascript" src="src/lists.js?version=2019-02-07"></script>

src/blocks.js

@@ -148,7 +148,7 @@ CustomCommandBlockMorph, SymbolMorph, ToggleButtonMorph, DialMorph*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.blocks = '2019-April-05';
+modules.blocks = '2019-April-08';
 
 var SyntaxElementMorph;
 var BlockMorph;
@@ -995,6 +995,21 @@ SyntaxElementMorph.prototype.labelPart = function (spec) {
                 true // read-only
             );
             break;
+        case '%aa': // audio attributes
+            part = new InputSlotMorph(
+                null, // text
+                false, // numeric?
+                {
+                    'name' : ['name'],
+                    'duration' : ['duration'],
+                    'length' : ['length'],
+                    'number of channels' : ['number of channels'],
+                    'sample rate' : ['sample rate'],
+                    'samples' : ['samples']
+                },
+                true // read-only
+            );
+            break;
         case '%month':
             part = new InputSlotMorph(
                 null, // text

src/objects.js

@@ -84,7 +84,7 @@ BlockEditorMorph, BlockDialogMorph, PrototypeHatBlockMorph, localize,
 TableMorph, TableFrameMorph, normalizeCanvas, BooleanSlotMorph, HandleMorph,
 AlignmentMorph, Process, XML_Element, VectorPaintEditorMorph*/
 
-modules.objects = '2019-April-05';
+modules.objects = '2019-April-08';
 
 var SpriteMorph;
 var StageMorph;
@@ -439,6 +439,12 @@ SpriteMorph.prototype.initBlocks = function () {
             category: 'sound',
             spec: 'stop all sounds'
         },
+        reportGetSoundAttribute: {
+            type: 'reporter',
+            category: 'sound',
+            spec: '%aa of sound %snd',
+            defaults: [['duration']]
+        },
         doRest: {
             type: 'command',
             category: 'sound',
@@ -2029,6 +2035,8 @@ SpriteMorph.prototype.blockTemplates = function (category) {
         blocks.push(block('doPlaySoundUntilDone'));
         blocks.push(block('doStopAllSounds'));
         blocks.push('-');
+        blocks.push(block('reportGetSoundAttribute'));
+        blocks.push('-');
         blocks.push(block('doRest'));
         blocks.push(block('doPlayNote'));
         blocks.push(block('doSetInstrument'));
@@ -7509,6 +7517,8 @@ StageMorph.prototype.blockTemplates = function (category) {
         blocks.push(block('doPlaySoundUntilDone'));
         blocks.push(block('doStopAllSounds'));
         blocks.push('-');
+        blocks.push(block('reportGetSoundAttribute'));
+        blocks.push('-');
         blocks.push(block('doRest'));
         blocks.push(block('doPlayNote'));
         blocks.push(block('doSetInstrument'));
@@ -9140,6 +9150,13 @@ CostumeEditorMorph.prototype.mouseMove
 function Sound(audio, name) {
     this.audio = audio; // mandatory
     this.name = name || "Sound";
+
+    // cached samples, don't persist
+    this.cachedSamples = null;
+
+    // internal for decoding, don't persist
+    this.audioBuffer = null; // for decoding ops
+    this.isDecoding = false;
 }
 
 Sound.prototype.play = function () {

src/threads.js

@@ -62,7 +62,7 @@ StageMorph, SpriteMorph, StagePrompterMorph, Note, modules, isString, copy,
 isNil, WatcherMorph, List, ListWatcherMorph, alert, console, TableMorph, Color,
 TableFrameMorph, ColorSlotMorph, isSnapObject, Map*/
 
-modules.threads = '2019-April-07';
+modules.threads = '2019-April-08';
 
 var ThreadManager;
 var Process;
@@ -2249,6 +2249,86 @@ Process.prototype.doStopAllSounds = function () {
     }
 };
 
+Process.prototype.reportGetSoundAttribute = function (choice, soundName) {
+    var sound = soundName instanceof Sound ? soundName : detect(
+            this.blockReceiver().sounds.asArray(),
+            function (s) {return s.name === soundName.toString(); }
+        ),
+        option = this.inputOption(choice);
+
+    if (option === 'name') {
+        return sound.name;
+    }
+
+    if (!sound.audioBuffer) {
+        this.decodeSound(sound);
+        return;
+    }
+
+    switch (option) {
+    case 'samples':
+        if (!sound.cachedSamples) {
+            sound.cachedSamples = function (sound) {
+                var buf = sound.audioBuffer,
+                    result, i;
+                if (buf.numberOfChannels > 1) {
+                    result = new List();
+                    for (i = 0; i < buf.numberOfChannels; i += 1) {
+                        result.add(new List(buf.getChannelData(i)));
+                    }
+                    return result;
+                }
+                return new List(buf.getChannelData(0));
+            } (sound);
+        }
+        return sound.cachedSamples;
+    case 'sample rate':
+        return sound.audioBuffer.sampleRate;
+    case 'duration':
+        return sound.audioBuffer.duration;
+    case 'length':
+        return sound.audioBuffer.length;
+    case 'number of channels':
+        return sound.audioBuffer.numberOfChannels;
+    default:
+        return 0;
+    }
+};
+
+Process.prototype.decodeSound = function (sound, callback) {
+    // private - callback is optional and invoked with sound as argument
+    var base64, binaryString, len, bytes, i, arrayBuffer, audioCtx,
+        myself = this;
+    if (sound.audioBuffer) {
+        return (callback || nop)(sound);
+    }
+    if (!sound.isDecoding) {
+        base64 = sound.audio.src.split(',')[1];
+        binaryString = window.atob(base64);
+        len = binaryString.length;
+        bytes = new Uint8Array(len);
+        for (i = 0; i < len; i += 1)        {
+            bytes[i] = binaryString.charCodeAt(i);
+        }
+        arrayBuffer = bytes.buffer;
+        audioCtx = Note.prototype.getAudioContext();
+        sound.isDecoding = true;
+        audioCtx.decodeAudioData(
+            arrayBuffer,
+            function(buffer) {
+                sound.audioBuffer = buffer;
+                sound.isDecoding = false;
+            },
+            function (err) {
+                sound.isDecoding = false;
+                myself.handleError(err);
+            }
+        );
+    }
+    this.pushContext('doYield');
+    this.pushContext();
+};
+
 // Process audio input (interpolated)
 
 Process.prototype.reportAudio = function (choice) {