tonegenerator - npm Package Compare versions

Comparing version 0.2.0 to 0.2.1

index.js

@@ -10,3 +10,3 @@ /*
   for(var i = 0; i < cycle; i++) {
-    tmp = volume * Math.sin((i/cycle) * Math.PI * 2);
+    tmp = Math.min(volume * Math.sin((i/cycle) * Math.PI * 2), volume - 1)
     data[i] = Math.round(tmp);
@@ -34,1 +34,4 @@ }
 };
+
+module.exports.MAX_16 = 32768;
+module.exports.MAX_8 = 128;

package.json

 {
   "name": "tonegenerator",
   "description": "Generates a tone as raw PCM WAV data, so you can do operations on it",
-  "version": "0.2.0",
+  "version": "0.2.1",
   "scripts": {
@@ -6,0 +6,0 @@ "test": "node test.js",

README.md

@@ -7,4 +7,6 @@ ToneGenerator for node.js
 
+## Generating Tones:
+
 ```javascript
-tone(frequency, lengthInSeconds, volume = 30, sampleRate, = 44100)
+tone(frequency, lengthInSeconds, volume = 30, sampleRate = 44100)
 ```
@@ -17,3 +19,3 @@
 ```javascript
-var tone = require("tonegenerator");
+var tone = require('tonegenerator');
 var A440 = tone(440, 20, 30); // get PCM data for a 440hz A, 20 seconds, volume 30
@@ -23,19 +25,11 @@ var A440_low_sample = tone(440, 20, 30, 22050); // this array has lower sample rate and will only be half as long
 
-I'm really unsure what the 'volume' value means, but you can use it to create
-different tones with different volumes, let me know how it works for you!
-
 The data is returned as a normal array, so you can do operations on it.
-Before writing to a file, you need to convert it to a buffer:
 
+## Combining notes
+
 ```javascript
-var tone = require("tonegenerator");
-// Use this package to write a header for the wave file
-// https://www.npmjs.org/package/waveheader
-var header = require("waveheader");
-var fs = require("fs");
-
 // An A-major chord
-var tone1 = tone(440, 2, 60);
-var tone2 = tone(554.37, 2, 30);
-var tone3 = tone(659.26, 2, 30);
+var tone1 = tone(440, 2, 60)
+var tone2 = tone(554.37, 2, 30)
+var tone3 = tone(659.26, 2, 30)
 
@@ -46,5 +40,3 @@ // "playing" one tone at the time
 // we can play them in a sequence
-var res = [].concat(tone1);
-res = res.concat(tone2);
-res = res.concat(tone3);
+var res = tone1.concat(tone2, tone3)
 
@@ -54,10 +46,126 @@ // By adding values of the tones for each sample,
 for(var i = 0; i < tone1.length; i++) {
-  res.push(tone1[i] + tone2[i] + tone3[i]);
+  res.push(tone1[i] + tone2[i] + tone3[i])
 }
+```
 
-// write to file (note conversion to buffer!)
-var writer = new fs.createWriteStream("A-major.wav");
-writer.write(header( 44100 * 8 )); // 44100 Hz * 8 seconds
-writer.write(new Buffer(res));
-writer.end();
+## Volume on 8-bit and 16-bit PCM data
+
+The meaning of the 'volume' value depends on whether you're creating 8-bit or 16-bit data. For 8-bit data, the max volume to avoid distortion is 128. For 16-bit data, the max volume is 32768. Those values are available as **require('tonegenerator').MAX_8** and **require('tonegenerator').MAX_16** respectively.
+
+## Writing 8-bit data to a Wave File
+Before writing your PCM data to a file, you need to convert it to a buffer of UInt8 values. 8-bit wave data goes from 0-255, so we need to add 128 to each value:
+
+```javascript
+var tone = require('tonegenerator');
+// Use this package to write a header for the wave file
+// https://www.npmjs.org/package/waveheader
+var header = require('waveheader');
+var fs = require('fs');
+
+var file = fs.createWriteStream('8bit-example.wav')
+var samples = tone(440, 2, tone.MAX_8)
+
+file.write(header(samples.length, {
+  bitDepth: 8
+}))
+
+// Convert -128 -> 127 range into 0 -> 255
+var data = Uint8Array.from(samples, function (val) {
+  return val + 128
+})
+
+if (Buffer.from) { // Node 5+
+  buffer = Buffer.from(data)
+} else {
+  buffer = new Buffer(data)
+}
+file.write(buffer)
+file.end()
 ```
+
+## Writing 16-bit data to a Wave file
+
+16-bit data requires a little bit more work, since we need to take Endianess into account. Unlike 8-bit data, the volumes does not start at 0, but at -32768.
+
+All the references to data length need to be doubled.
+
+```javascript
+var tone = require('tonegenerator');
+var header = require('waveheader');
+var fs = require('fs');
+
+var file = fs.createWriteStream('16bit-example.wav')
+var samples = tone(440, 2, tone.MAX_16)
+
+file.write(header(samples.length * 2, {
+  bitDepth: 16
+}))
+
+var data = Int16Array.from(samples)
+
+var size = data.length * 2 // 2 bytes per sample
+if (Buffer.allocUnsafe) { // Node 5+
+  buffer = Buffer.allocUnsafe(size)
+} else {
+  buffer = new Buffer(size)
+}
+
+data.forEach(function (value, index) {
+  buffer.writeInt16LE(value, index * 2)
+})
+
+file.write(buffer)
+file.end()
+```
+
+## Writing stereo sounds
+
+In stereo wave data, the sample for each channel comes right after each other.
+The principle looks like `[sample0-1 sample0-2 sample1-1 sample1-2]`. So we need to
+first generate the data for each channel, then interleave them.
+
+
+```javascript
+var tone = require('tonegenerator');
+var header = require('waveheader');
+var fs = require('fs');
+
+var file = fs.createWriteStream('16bit-stereo.wav')
+// A loud A for channel 1
+var channel1 = tone(440, 2, tone.MAX_16)
+// A not so loud C for channel 2
+var channel2 = tone(554.37, 2, tone.MAX_16 / 4)
+
+// create an array where the 2 channels are interleaved:
+var samples = []
+for (var i = 0; i < channel1.length; i++) {
+  samples.push(channel1[i])
+  samples.push(channel2[i])
+}
+
+file.write(header(samples.length * 2, {
+  channels: 2,
+  bitDepth: 16
+}))
+
+var data = Int16Array.from(samples)
+
+var size = data.length * 2 // 2 bytes per sample
+if (Buffer.allocUnsafe) { // Node 5+
+  buffer = Buffer.allocUnsafe(size)
+} else {
+  buffer = new Buffer(size)
+}
+
+data.forEach(function (value, index) {
+  buffer.writeInt16LE(value, index * 2)
+})
+
+file.write(buffer)
+file.end()
+```
+
+## Reading:
+
+* [Wave PCM SoundFile format](http://soundfile.sapp.org/doc/WaveFormat/) - make sure to read the 'Notes' section
+* [ABC of Uncompressed digital audio](http://blog.bjornroche.com/2013/05/the-abcs-of-pcm-uncompressed-digital.html)

test.js

@@ -13,5 +13,8 @@ var assert = require('assert')
 
-assert.strictEqual(Math.max.apply(Math, tone1), 10, 'takes the volume argument as max')
-assert.strictEqual(Math.min.apply(Math, tone1), -10, 'takes the volume argument as max')
-assert.strictEqual(Math.max.apply(Math, tone2), 30, 'takes the volume argument as max')
+// takes the volume argument - 1 as max
+assert.strictEqual(Math.max.apply(Math, tone1), 9)
+// takes the volume argument as min
+assert.strictEqual(Math.min.apply(Math, tone1), -10)
+// takes the volume argument as max
+assert.strictEqual(Math.max.apply(Math, tone2), 29)
 
@@ -18,0 +21,0 @@ assert.equal(tone1.length/2, tonefrequency.length, 'when halving audio sampling rate, the array length should be half of default')

No alert changes

Improved metrics

Total package byte prevSize

7087

increased by66.91%

Lines of code

45

increased by12.5%

Number of lines in readme file

167

increased by183.05%

No dependency changes