Use Web Audio API to generate the morse audio

README.md

@@ -3,7 +3,7 @@
 [![npm-version]][npm] [![npm-downloads]][npm] [![travis-ci]][travis]
 
 Morse code encoder and decoder with no dependencies supports Latin, Cyrillic, Greek, Hebrew, 
-Arabic, Persian, Japanese, and Korean characters with audio generation functionality.
+Arabic, Persian, Japanese, and Korean characters with audio generation functionality using the [Web Audio API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API). 
 
 ## Installation
 
@@ -24,19 +24,23 @@ $ yarn add morsify
 ```js
 var morsify = require('morsify');
 
-morsify.encode('SOS'); // .../---/... 
-morsify.decode('.../---/...'); // S O S
-morsify.audio('SOS'); // will return base64 encoded audio/wav data
+var encoded = morsify.encode('SOS'); // .../---/... 
+var decoded = morsify.decode('.../---/...'); // S O S
+var audio = morsify.audio('SOS'), oscillator = audio.oscillator; // OscillatorNode
+audio.play(); // play audio
+audio.stop(); // stop audio
 ```
 
 Or alternatively, you can also use the library directly with including the source file.
 
 ```html
 <script src="https://rawgit.com/ozdemirburak/morsify/master/index.js"></script>
 <script>
-    console.log(morsify.encode('SOS')); // .../---/... 
-    console.log(morsify.decode('.../---/...')); // S O S
-    console.log(morsify.audio('SOS')); // will return base64 encoded audio/wav data
+    var encoded = morsify.encode('SOS'); // .../---/... 
+    var decoded = morsify.decode('.../---/...'); // S O S
+    var audio = morsify.audio('SOS'), oscillator = audio.oscillator; // OscillatorNode
+    audio.play(); // play audio
+    audio.stop(); // stop audio
 </script>
 ```
 
@@ -52,7 +56,7 @@ Set the priority option according to the list below.
 - 1 => ASCII (Default)
 - 2 => Numbers
 - 3 => Punctuation
-- 4 => Latin Extended (Turkish, Polski etc.)
+- 4 => Latin Extended (Turkish, Polish etc.)
 - 5 => Cyrillic
 - 6 => Greek
 - 7 => Hebrew
@@ -62,18 +66,21 @@ Set the priority option according to the list below.
 - 11 => Korean
 
 ```js
-morsify.encode('Ленинград', { priority: 5 }) // .-.././-./../-./--./.-./.-/-..
-morsify.decode('.../.-/--./.-/.--./.--', { priority: 6 }) // Σ Α Γ Α Π Ω
-morsify.decode('––– –... ––– –. ––. .. .–.. –––', { dash: '–', dot: '.', space: ' ', priority: 7 }) // ה ב ה נ ג י ל ה
-morsify.audio('البُراق‎‎', { // generates the morse .-/.-../-.../.-./.-/--.- then generates the audio from it
-  channels: 1, 
-  sampleRate: 1012, 
-  bitDepth: 16,
-  unit: 0.1,
-  frequency: 440.0,
-  volume: 32767,
-  priority: 8
-})
+var cyrillic = morsify.encode('Ленинград', { priority: 5 }) // .-.././-./../-./--./.-./.-/-..
+var greek = morsify.decode('.../.-/--./.-/.--./.--', { priority: 6 }) // Σ Α Γ Α Π Ω
+var hebrew = morsify.decode('––– –... ––– –. ––. .. .–.. –––', { dash: '–', dot: '.', space: ' ', priority: 7 }) // ה ב ה נ ג י ל ה
+var arabicAudio = morsify.audio('البُراق‎‎', { // generates the morse .-/.-../-.../.-./.-/--.- then generates the audio from it
+  unit: 0.1, // period of one unit, in seconds, 1.2 / c where c is speed of transmission, in words per minute
+  oscillator: {
+    type: 'sine', // sine, square, sawtooth, triangle
+    frequency: 500,  // value in hertz
+    onended: function () { // event that fires when the tone has stopped playing
+      console.log('ended');
+    },
+  }
+}), oscillator = arabicAudio.oscillator; // OscillatorNode
+arabicAudio.play(); // will start playing morse audio
+arabicAudio.stop(); // will stop playing morse audio
 ```
 
 ## Contributing and Known Issues
@@ -84,8 +91,6 @@ Currently, as a major drawback, Chinese characters are missing. Someone with the
 [Chinese telegraph code](https://en.wikipedia.org/wiki/Chinese_telegraph_code) can help to implement it. Also someone who is proficient in Thai can help
 to include [Thai alphabet](https://th.wikipedia.org/wiki/รหัสมอร์ส).
 
-On the other hand, audio generated by the script is playable in Firefox, however, Chrome support is currently missing.
-
 ## License
 The MIT License (MIT). Please see [License File](LICENSE) for more information.
 

index.js

@@ -36,7 +36,7 @@
       'Ș': '1111', 'Š': '1111', 'Ŝ': '00010', 'ß': '000000', 'Þ': '01100', 'Ü': '0011',
       'Ù': '0011', 'Ŭ': '0011', 'Ž': '11001', 'Ź': '110010', 'Ż': '11001'
     },
-    '5': { // Cyrilic Alphabet => https://en.wikipedia.org/wiki/Russian_Morse_code
+    '5': { // Cyrillic Alphabet => https://en.wikipedia.org/wiki/Russian_Morse_code
       'А': '01', 'Б': '1000', 'В': '011', 'Г': '110', 'Д': '100', 'Е': '0',
       'Ж': '0001', 'З': '1100', 'И': '00', 'Й': '0111', 'К': '101','Л': '0100',
       'М': '11', 'Н': '10', 'О': '111', 'П': '0110', 'Р': '010', 'С': '000',
@@ -105,18 +105,19 @@
 
   var getOptions = function (options) {
     options = options || {};
+    options.oscillator = options.oscillator || {};
     options = {
       dash: options.dash || '-',
       dot: options.dot || '.',
       space: options.space || '/',
       invalid: options.invalid || '#',
       priority: options.priority || 1,
-      channels: options.channels || 1,
-      sampleRate: options.sampleRate || 1012,
-      bitDepth: options.bitDepth || 16,
-      unit: options.unit || 0.1,
-      frequency: options.frequency || 440.0,
-      volume: options.volume || 32767
+      unit: options.unit || 0.08, // period of one unit, in seconds, 1.2 / c where c is speed of transmission, in words per minute
+      oscillator: {
+        type: options.oscillator.type || 'sine', // sine, square, sawtooth, triangle
+        frequency: options.oscillator.frequency || 500,  // value in hertz
+        onended: options.oscillator.onended || null,  // event that fires when the tone has stopped playing
+      }
     };
     characters[0] = characters[options.priority];
     return options;
@@ -141,29 +142,24 @@
     }).join(' ').replace(/\s+/g, ' ');
   };
 
-  // Source: https://github.com/mattt/Morse.js
   var audio = function (text, opts) {
-    var options = getOptions(opts), morse = encode(text, opts), data = [], samples = 0,
-      pack = function (e) {
-        for (var b = '', c = 1, d = 0; d < e.length; d++) {
-          var f = e.charAt(d), a = arguments[c++];
-          b += f === 'v' ? String.fromCharCode(a & 255, a >> 8 & 255) : String.fromCharCode(a & 255, a >> 8 & 255, a >> 16 & 255, a >> 24 & 255);
-        }
-        return b;
-      }, tone = function (length) {
-        for (var i = 0; i < options.sampleRate * options.unit * length; i++) {
-          for (var c = 0; c < options.channels; c++) {
-            var v = options.volume * Math.sin((2 * Math.PI) * (i / options.sampleRate) * options.frequency);
-            data.push(pack('v', v)); samples++;
-          }
-        }
-      }, silence = function (length) {
-        for (var i = 0; i < options.sampleRate * options.unit * length; i++) {
-          for (var c = 0; c < options.channels; c++) {
-            data.push(pack('v', 0)); samples++;
-          }
-        }
-      };
+    var options = getOptions(opts), morse = encode(text, opts),
+      AudioContext = window.AudioContext || window.webkitAudioContext, ctx = new AudioContext(),
+      t = ctx.currentTime, oscillator = ctx.createOscillator(), gainNode = ctx.createGain();
+
+    oscillator.type = options.oscillator.type;
+    oscillator.frequency.value = options.oscillator.frequency;
+    oscillator.onended = options.oscillator.onended;
+
+    gainNode.gain.setValueAtTime(0, t);
+
+    var tone = function (i) {
+      gainNode.gain.setValueAtTime(1, t);
+      t += i * options.unit;
+    }, silence = function (i) {
+      gainNode.gain.setValueAtTime(0, t);
+      t += i * options.unit;
+    };
 
     for (var i = 0; i <= morse.length; i++) {
       if (morse[i] === options.space) {
@@ -179,34 +175,19 @@
       }
     }
 
-    var chunk1 = [
-        'fmt ',
-        pack('V', 16),
-        pack('v', 1),
-        pack('v', options.channels),
-        pack('V', options.sampleRate),
-        pack('V', options.sampleRate * options.channels * options.bitDepth / 8),
-        pack('v', options.channels * options.bitDepth / 8),
-        pack('v', options.bitDepth)
-      ].join(''),
-      chunk2 = [
-        'data',
-        pack('V', samples * options.channels * options.bitDepth / 8),
-        data.join('')
-      ].join(''),
-      header = [
-        'RIFF',
-        pack('V', 4 + (8 + chunk1.length) + (8 + chunk2.length)),
-        'WAVE'
-      ].join('');
+    oscillator.connect(gainNode);
+    gainNode.connect(ctx.destination);
 
-    if (typeof btoa === 'undefined') {
-      global.btoa = function (str) {
-        return new Buffer(str).toString('base64');
-      };
-    }
-
-    return 'data:audio/wav;base64,' + encodeURI(btoa([header, chunk1, chunk2].join('')));
+    return {
+      play: function () {
+        oscillator.start();
+        oscillator.stop(t);
+      },
+      stop: function () {
+        oscillator.stop();
+      },
+      oscillator: oscillator
+    };
   };
 
   return {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "morsify",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "description": "Encodes and decodes morse code, creates morse code audio from text.",
   "keywords": [
     "morse",

test/index.js

@@ -158,8 +158,4 @@ describe('morsify', function () {
     t.equal(morsify.decode('---/.---/./../-/...', options), 'ㅍ ㅎ ㅏ ㅑ ㅓ ㅕ');
     t.equal(morsify.decode('.-/-./..../.-./-../..-', options), 'ㅗ ㅛ ㅜ ㅠ ㅡ ㅣ');
   });
-  it('creates audio', function () {
-    t.equal('data:audio/wav;base64', morsify.audio('SOS').substr(0, 21));
-    t.equal('UklGRsK8IAAAV0FWRWZtdCAQAAAAAQABAMO0AwAAw6gHAAACABAAZGF0YcKIIAAAAADDvjJ1wqLCm3hOwoDCpXE6wq/CiCJtEX/CvcKRaMKvwoJRfW/Cl8KBQsKTw654w53DhlBbwo7Csn9lwofCi10Cw40AAMO+MnXCosKbeE7CgMKlcTrCr8KIIm0Rf8K9wpFowq/CglF9b8KXwoFCwpPDrnjDncOGUFvCjsKyf2XCh8KLXQLDjQAAw74ydcKiwpt4TsKAwqVxOsKvwogibRF/wr3CkWjCr8KCUX1vwpfCgULCk8OueMOdw4ZQW8KOwrJ/ZcKHwotdAsONAADDvjJ1wqLCm3hOwoDCpXE6wq/CiCJtEX/CvcKRaMKvwoJRfW/Cl8KBQsKTw654w53DhlBbwo7Csn9lwofCi10Cw40AAMO+MnXCosKbeE7CgMKlcTrCr8KIIm0Rf8K', morsify.audio('SOS').substr(22, 463));
-  });
 });