From d1d98337c8d777121c5a36e7135b484416dce033 Mon Sep 17 00:00:00 2001
From: Paul Kaplan <pkaplan@media.mit.edu>
Date: Thu, 19 Dec 2019 16:01:21 -0500
Subject: [PATCH] Update docs and tests
---
src/containers/sound-editor.jsx | 30 ++++++++++++++++--------------
src/lib/audio/audio-util.js | 29 +++++++++++++++++++++++------
test/unit/util/audio-util.test.js | 18 +++++++++---------
3 files changed, 48 insertions(+), 29 deletions(-)
diff --git a/src/containers/sound-editor.jsx b/src/containers/sound-editor.jsx
index 61bf71224..3089b3dc3 100644
--- a/src/containers/sound-editor.jsx
+++ b/src/containers/sound-editor.jsx
@@ -10,7 +10,7 @@ import {
computeChunkedRMS,
encodeAndAddSoundToVM,
downsampleIfNeeded,
- backupDownSampler
+ dropEveryOtherSample
} from '../lib/audio/audio-util.js';
import AudioEffects from '../lib/audio/audio-effects.js';
import SoundEditorComponent from '../components/sound-editor/sound-editor.jsx';
@@ -138,7 +138,7 @@ class SoundEditor extends React.Component {
});
}
submitNewSamples (samples, sampleRate, skipUndo) {
- return downsampleIfNeeded(samples, sampleRate, this.resampleBufferToRate)
+ return downsampleIfNeeded({samples, sampleRate}, this.resampleBufferToRate)
.then(({samples: newSamples, sampleRate: newSampleRate}) =>
WavEncoder.encode({
sampleRate: newSampleRate,
@@ -208,9 +208,9 @@ class SoundEditor extends React.Component {
trimEnd: null
});
});
-
}
handleDeleteInverse () {
+ // Delete everything outside of the trimmers
const {samples, sampleRate} = this.copyCurrentBuffer();
const sampleCount = samples.length;
const startIndex = Math.floor(this.state.trimStart * sampleCount);
@@ -331,19 +331,21 @@ class SoundEditor extends React.Component {
const sampleRateRatio = newRate / buffer.sampleRate;
const newLength = sampleRateRatio * buffer.samples.length;
let offlineContext;
- if (window.OfflineAudioContext) {
- offlineContext = new window.OfflineAudioContext(1, newLength, newRate);
- } else if (window.webkitOfflineAudioContext) {
- try {
+ // Try to use either OfflineAudioContext or webkitOfflineAudioContext to resample
+ // The constructors will throw if trying to resample at an unsupported rate
+ // (e.g. Safari/webkitOAC does not support lower than 44khz).
+ try {
+ if (window.OfflineAudioContext) {
+ offlineContext = new window.OfflineAudioContext(1, newLength, newRate);
+ } else if (window.webkitOfflineAudioContext) {
offlineContext = new window.webkitOfflineAudioContext(1, newLength, newRate);
- } catch {
- if (newRate === (buffer.sampleRate / 2)) {
- return resolve(backupDownSampler(buffer, newRate));
- }
- return reject('Could not resample');
}
- } else {
- return reject('No offline audio context');
+ } catch {
+ // If no OAC available and downsampling by 2, downsample by dropping every other sample.
+ if (newRate === buffer.sampleRate / 2) {
+ return resolve(dropEveryOtherSample(buffer));
+ }
+ return reject('Could not resample');
}
const source = offlineContext.createBufferSource();
const audioBuffer = offlineContext.createBuffer(1, buffer.samples.length, buffer.sampleRate);
diff --git a/src/lib/audio/audio-util.js b/src/lib/audio/audio-util.js
index 199b66af9..fba6be96b 100644
--- a/src/lib/audio/audio-util.js
+++ b/src/lib/audio/audio-util.js
@@ -1,5 +1,4 @@
import WavEncoder from 'wav-encoder';
-import log from '../log.js';
const SOUND_BYTE_LIMIT = 10 * 1000 * 1000; // 10mb
@@ -60,7 +59,21 @@ const encodeAndAddSoundToVM = function (vm, samples, sampleRate, name, callback)
});
};
-const downsampleIfNeeded = (samples, sampleRate, resampler) => {
+/**
+ @typedef SoundBuffer
+ @type {Object}
+ @property {Float32Array} samples Array of audio samples
+ @property {number} sampleRate Audio sample rate
+ */
+
+/**
+ * Downsample the given buffer to try to reduce file size below SOUND_BYTE_LIMIT
+ * @param {SoundBuffer} buffer - Buffer to resample
+ * @param {function(SoundBuffer):Promise<SoundBuffer>} resampler - resampler function
+ * @returns {SoundBuffer} Downsampled buffer with half the sample rate
+ */
+const downsampleIfNeeded = (buffer, resampler) => {
+ const {samples, sampleRate} = buffer;
const duration = samples.length / sampleRate;
const encodedByteLength = samples.length * 2; /* bitDepth 16 bit */
// Resolve immediately if already within byte limit
@@ -76,8 +89,12 @@ const downsampleIfNeeded = (samples, sampleRate, resampler) => {
return Promise.reject('Sound too large to save, refusing to edit');
};
-const backupDownSampler = (buffer, newRate) => {
- log.warn(`Using backup down sampler for conversion from ${buffer.sampleRate} to ${newRate}`);
+/**
+ * Drop every other sample of an audio buffer as a last-resort way of downsampling.
+ * @param {SoundBuffer} buffer - Buffer to resample
+ * @returns {SoundBuffer} Downsampled buffer with half the sample rate
+ */
+const dropEveryOtherSample = buffer => {
const newLength = Math.floor(buffer.samples.length / 2);
const newSamples = new Float32Array(newLength);
for (let i = 0; i < newLength; i++) {
@@ -85,7 +102,7 @@ const backupDownSampler = (buffer, newRate) => {
}
return {
samples: newSamples,
- sampleRate: newRate
+ sampleRate: buffer.rate / 2
};
};
@@ -94,5 +111,5 @@ export {
computeChunkedRMS,
encodeAndAddSoundToVM,
downsampleIfNeeded,
- backupDownSampler
+ dropEveryOtherSample
};
diff --git a/test/unit/util/audio-util.test.js b/test/unit/util/audio-util.test.js
index 01753b2ac..79ff55e8b 100644
--- a/test/unit/util/audio-util.test.js
+++ b/test/unit/util/audio-util.test.js
@@ -2,7 +2,7 @@ import {
computeRMS,
computeChunkedRMS,
downsampleIfNeeded,
- backupDownSampler
+ dropEveryOtherSample
} from '../../../src/lib/audio/audio-util';
describe('computeRMS', () => {
@@ -60,38 +60,38 @@ describe('downsampleIfNeeded', () => {
const sampleRate = 44100;
test('returns given data when no downsampling needed', async () => {
samples.length = 1;
- const res = await downsampleIfNeeded(samples, sampleRate, null);
+ const res = await downsampleIfNeeded({samples, sampleRate}, null);
expect(res.samples).toEqual(samples);
expect(res.sampleRate).toEqual(sampleRate);
});
test('downsamples to 22050 if that puts it under the limit', async () => {
samples.length = 44100 * 3 * 60;
const resampler = jest.fn(() => 'TEST');
- const res = await downsampleIfNeeded(samples, sampleRate, resampler);
+ const res = await downsampleIfNeeded({samples, sampleRate}, resampler);
expect(resampler).toHaveBeenCalledWith({samples, sampleRate}, 22050);
expect(res).toEqual('TEST');
});
test('fails if resampling would not put it under the limit', async () => {
samples.length = 44100 * 4 * 60;
try {
- await downsampleIfNeeded(samples, sampleRate, null);
+ await downsampleIfNeeded({samples, sampleRate}, null);
} catch (e) {
expect(e).toEqual('Sound too large to save, refusing to edit');
}
});
});
-describe('backupDownSampler', () => {
+describe('dropEveryOtherSample', () => {
const buffer = {
- samples: [1, 0, 1, 0, 1, 0, 1],
+ samples: [1, 0, 2, 0, 3, 0],
sampleRate: 2
};
test('result is half the length', () => {
- const {samples} = backupDownSampler(buffer, 1);
+ const {samples} = dropEveryOtherSample(buffer, 1);
expect(samples.length).toEqual(Math.floor(buffer.samples.length / 2));
});
test('result contains only even-index items', () => {
- const {samples} = backupDownSampler(buffer, 1);
- expect(samples.every(v => v === 1)).toBe(true);
+ const {samples} = dropEveryOtherSample(buffer, 1);
+ expect(samples).toEqual(new Float32Array([1, 2, 3]));
});
});
--
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