Merge f8de8b0 into 0bad66d

lib/wavefile-creator.js

@@ -34,7 +34,7 @@ import interleave from './interleave';
 import dwChannelMask from './dw-channel-mask';
 import validateNumChannels from './validate-num-channels'; 
 import validateSampleRate from './validate-sample-rate';
-import {packArrayTo, packTo, unpack} from 'byte-data';
+import {packArrayTo, packTo, unpack, unpackArray} from 'byte-data';
 
 /**
  * A class to read, write and create wav files.
@@ -176,6 +176,25 @@ export default class WaveFileCreator extends WaveFileParser {
       this.dataType);
   }
 
+    /**
+     * Return the sample at a given index.
+     * @param {number} startIndex The sample start index.
+     * @param {number} stopIndex The sample stop index.
+     * @return {number} The sample.
+     * @throws {Error} If the sample index is off range.
+     */
+    getSamples(startIndex, stopIndex) {
+        startIndex = startIndex * (this.dataType.bits / 8);
+        stopIndex = stopIndex * (this.dataType.bits / 8);
+        if (stopIndex + this.dataType.bits / 8 > this.data.samples.length) {
+            throw new Error('Range error');
+        }
+        return unpackArray(
+            this.data.samples.slice(startIndex, stopIndex),
+            this.dataType
+        );
+    }
+
   /**
    * Set the sample at a given index.
    * @param {number} index The sample index.

test/src/getSamples.js

@@ -0,0 +1,67 @@
+/**
+ * WaveFile: https://github.com/rochars/wavefile
+ * Copyright (c) 2017-2018 Rafael da Silva Rocha, Andreas Geissinger. MIT License.
+ *
+ * Test writing 8-bit files with the fromScratch() method.
+ *
+ */
+
+var assert = assert || require('assert');
+var WaveFile = WaveFile || require('../loader.js');
+
+describe('getSamples(): 8-bit wave file from scratch', function() {
+
+    var wav = new WaveFile();
+    wav.fromScratch(1, 48000, '8', [0, 255, 2, 3]);
+
+    it('samples from 0 - 1 should be 0, 255', function() {
+        assert.equal(wav.getSamples(0,1), [0,255]);
+    });
+
+    it('samples from 0 - 4 should throw error', function() {
+        assert.throws(function() {wav.getSamples(0,4);}, Error);
+    });
+});
+
+describe('getSamples(): 16-bit wave file from scratch', function() {
+
+    var wav = new WaveFile();
+    wav.fromScratch(1, 48000, '16', [0, 1, -32768, 32767]);
+
+    it('samples from 0 - 1 should be 0, 255', function() {
+        assert.equal(wav.getSamples(0, 1), [0, 255]);
+    });
+
+    it('sample from 0 - 4 should throw error', function() {
+        assert.throws(function() {wav.getSamples(0, 4);}, Error);
+    });
+});
+
+describe('getSamples(): 24-bit wave file from scratch', function() {
+
+    var wav = new WaveFile();
+    wav.fromScratch(1, 48000, '24', [0, 1, -8388608, 8388607]);
+
+    it('samples from 0 - 1 should be 0, 1', function() {
+        assert.equal(wav.getSamples(0, 1), [0, 1]);
+    });
+
+    it('samples from 0 - 4 should throw error', function() {
+        assert.throws(function() {wav.getSamples(0, 4);}, Error);
+    });
+});
+
+describe('getSamples(): 32-bit wave file from scratch', function() {
+
+    var wav = new WaveFile();
+    wav.fromScratch(1, 44100, '32', [0, 1, -2147483648, 2147483647]);
+
+    it('samples from 0 - 1 should be 0, 1', function() {
+        assert.equal(wav.getSamples(0, 1), [0, 1]);
+    });
+
+    it('sample from 0 - 4 should throw error', function() {
+        assert.throws(function() {wav.getSamples(0, 4);}, Error);
+    });
+
+});