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import {
computeRMS,
computeChunkedRMS,
downsampleIfNeeded,
dropEveryOtherSample
} from '../../../src/lib/audio/audio-util';
describe('computeRMS', () => {
test('returns 0 when given no samples', () => {
expect(computeRMS([])).toEqual(0);
});
test('returns the RMS scaled by the given unity value and square rooted', () => {
const unity = 0.5;
const samples = [3, 2, 1];
expect(computeRMS(samples, unity)).toEqual(
Math.sqrt(Math.sqrt(((3 * 3) + (2 * 2) + (1 * 1)) / 3) / 0.5)
);
});
test('uses a default unity value of 0.55', () => {
const samples = [1, 1, 1];
// raw rms is 1, scaled to (1 / 0.55) and square rooted
expect(computeRMS(samples)).toEqual(Math.sqrt(1 / 0.55));
});
});
describe('computeChunkedRMS', () => {
test('computes the rms for each chunk based on chunk size', () => {
const samples = [2, 1, 3, 2, 5];
const chunkedLevels = computeChunkedRMS(samples, 2);
// chunked to [2, 0], [3, 0], [5]
// rms scaled with default unity of 0.55
expect(chunkedLevels.length).toEqual(3);
expect(chunkedLevels).toEqual([
Math.sqrt(Math.sqrt(((2 * 2) + (1 * 1)) / 2) / 0.55),
Math.sqrt(Math.sqrt(((3 * 3) + (2 * 2)) / 2) / 0.55),
Math.sqrt(Math.sqrt((5 * 5) / 1) / 0.55)
]);
});
test('chunk size larger than sample size creates single chunk', () => {
const samples = [1, 1, 1];
const chunkedLevels = computeChunkedRMS(samples, 7);
// chunked to [1, 1, 1]
// rms scaled with default unity of 0.55
expect(chunkedLevels.length).toEqual(1);
expect(chunkedLevels).toEqual([Math.sqrt(1 / 0.55)]);
});
test('chunk size as multiple is handled correctly', () => {
const samples = [1, 1, 1, 1, 1, 1];
const chunkedLevels = computeChunkedRMS(samples, 3);
// chunked to [1, 1, 1], [1, 1, 1]
// rms scaled with default unity of 0.55
expect(chunkedLevels.length).toEqual(2);
expect(chunkedLevels).toEqual([Math.sqrt(1 / 0.55), Math.sqrt(1 / 0.55)]);
});
});
describe('downsampleIfNeeded', () => {
const samples = {length: 1};
const sampleRate = 44100;
test('returns given data when no downsampling needed', async () => {
samples.length = 1;
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);
expect(resampler).toHaveBeenCalledWith({samples, sampleRate}, 22050);
expect(res).toEqual('TEST');
});
// TW: We allow resampling even if it would exceed the limit because our GUI handles this better.
test.skip('fails if resampling would not put it under the limit', async () => {
samples.length = 44100 * 4 * 60;
try {
await downsampleIfNeeded({samples, sampleRate}, null);
} catch (e) {
expect(e.message).toEqual('Sound too large to save, refusing to edit');
}
});
});
describe('dropEveryOtherSample', () => {
const buffer = {
samples: [1, 0, 2, 0, 3, 0],
sampleRate: 2
};
test('result is half the length', () => {
const {samples} = dropEveryOtherSample(buffer);
expect(samples.length).toEqual(Math.floor(buffer.samples.length / 2));
});
test('result contains only even-index items', () => {
const {samples} = dropEveryOtherSample(buffer);
expect(samples).toEqual(new Float32Array([1, 2, 3]));
});
test('result sampleRate is given sampleRate / 2', () => {
const {sampleRate} = dropEveryOtherSample(buffer);
expect(sampleRate).toEqual(buffer.sampleRate / 2);
});
});
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