audio_buffer.js

class AlphabetGenerator {

	constructor() {
		const context_name = '_MORSE_AUDIO_CONTEXT'
		var ac = window[context_name] || new window.AudioContext();
		var an = ac.createAnalyser();
		an.connect(ac.destination);
		an.minDecibels = -140;
		an.maxDecibels = 0;
		this._audio_loaded = false;
		this._queue = [];
		this.context = ac;
		this.analyser = an;
		var my = this;
		this.parseSubtitles();
		this.loadAudio('nato.ogg', function() { my.audioLoaded(); });
	}

	loadAudio(url, fun=function(){}) {
		var req = new XMLHttpRequest();
		req.open("GET", url, true);
		req.responseType = "arraybuffer";
		var ac = this.context;
		req.onreadystatechange = function(b) {
			if (req.readyState != 4) return;
			ac.decodeAudioData(req.response, function(buffer) {
				if (!buffer.state) fun(buffer);
			});
		}
		req.send();
	}

	audioLoaded() {
		this._audio_loaded = true;
		for (let m in this._queue) this.spellString(m);
	}

	parseSubtitles() {
		var subs = NATO_SUBTITLES.split('\n');
		this.times = {};
		var i = 0;
		var time = false;
		for (let l of subs) { // Chunk into 4.
			if (i == 1) time = l;
			if (i == 2) this.times[l] = this.parseTime(time);
			if (i == 3) i = 0;
			else i++;
		}
	}

	parseTime(time) {
		console.log("parsing")
		var times = [];
		for (let t of time.split(' --> ')) {
			let [h, m, s] = t.split(":");
			times.push(h*60*60+m*60+parseFloat(s.replace(',', '.')));
		}
		console.log("done parsing")
		return times;
	}

	spellString(str) {
		for (let c in str) {
			c = c.toUpperCase();
			
		}
	}

}

// Subtitles from Wikipedia.
const NATO_SUBTITLES = `1
00:00:00,700 --> 00:00:01,800
A

2
00:00:01,900 --> 00:00:03,000
B

3
00:00:03,100 --> 00:00:04,000
C

4
00:00:04,100 --> 00:00:05,000
D

5
00:00:05,200 --> 00:00:06,300
E

6
00:00:06,300 --> 00:00:07,500
F

7
00:00:07,900 --> 00:00:08,700
G

8
00:00:08,900 --> 00:00:10,000
H

9
00:00:10,100 --> 00:00:11,100
I

10
00:00:11,400 --> 00:00:12,400
J

11
00:00:12,500 --> 00:00:13,500
K

12
00:00:13,700 --> 00:00:14,700
L

13
00:00:15,000 --> 00:00:16,000
M

14
00:00:16,200 --> 00:00:17,300
N

15
00:00:17,500 --> 00:00:18,500
O

16
00:00:18,700 --> 00:00:19,500
P

17
00:00:19,900 --> 00:00:21,000
Q

18
00:00:21,100 --> 00:00:22,200
R

19
00:00:22,400 --> 00:00:23,300
S

20
00:00:23,700 --> 00:00:24,500
T

21
00:00:24,900 --> 00:00:26,000
U

22
00:00:26,200 --> 00:00:27,300
V

23
00:00:27,400 --> 00:00:28,500
W

24
00:00:28,700 --> 00:00:30,000
X

25
00:00:30,200 --> 00:00:31,200
Y

26
00:00:31,500 --> 00:00:32,500
Z

27
00:00:33,500 --> 00:00:34,500
0

28
00:00:34,700 --> 00:00:35,500
1

29
00:00:35,700 --> 00:00:36,900
2

30
00:00:37,000 --> 00:00:38,000
3

31
00:00:38,100 --> 00:00:39,000
4

32
00:00:39,300 --> 00:00:40,200
5

33
00:00:40,400 --> 00:00:41,500
6

34
00:00:41,600 --> 00:00:42,700
7

35
00:00:43,000 --> 00:00:44,000
8

36
00:00:44,100 --> 00:00:44,700
9`