mediabunny/test/browser/audio-samples.test.ts

import { expect, test } from 'vitest';
import { AudioSample } from '../../src/sample.js';

const SAMPLE_RATE = 48000;
const NUM_CHANNELS = 2;
const NUM_FRAMES = 10;
const TIMESTAMP = 1;

const cellValue = (frame: number, channel: number) => frame * 10 + channel;

const makeInterleavedSample = () => {
	const data = new Int16Array(NUM_FRAMES * NUM_CHANNELS);
	for (let f = 0; f < NUM_FRAMES; f++) {
		for (let c = 0; c < NUM_CHANNELS; c++) {
			data[f * NUM_CHANNELS + c] = cellValue(f, c);
		}
	}

	return new AudioSample({
		data,
		format: 's16',
		sampleRate: SAMPLE_RATE,
		numberOfChannels: NUM_CHANNELS,
		timestamp: TIMESTAMP,
	});
};

const makePlanarSample = () => {
	const data = new Float32Array(NUM_FRAMES * NUM_CHANNELS);
	for (let c = 0; c < NUM_CHANNELS; c++) {
		for (let f = 0; f < NUM_FRAMES; f++) {
			data[c * NUM_FRAMES + f] = cellValue(f, c);
		}
	}

	return new AudioSample({
		data,
		format: 'f32-planar',
		sampleRate: SAMPLE_RATE,
		numberOfChannels: NUM_CHANNELS,
		timestamp: TIMESTAMP,
	});
};

const readCell = (sample: AudioSample, frame: number, channel: number) => {
	if (sample.format === 's16') {
		const out = new Int16Array(sample.numberOfFrames * sample.numberOfChannels);
		sample.copyTo(out, { planeIndex: 0, format: 's16' });
		return out[frame * sample.numberOfChannels + channel];
	} else {
		const out = new Float32Array(sample.numberOfFrames);
		sample.copyTo(out, { planeIndex: channel, format: 'f32-planar' });
		return out[frame];
	}
};

for (const [label, makeSample] of [
	['interleaved', makeInterleavedSample],
	['planar', makePlanarSample],
] as const) {
	test(`trim, normal case (${label})`, () => {
		using sample = makeSample();
		using trimmed = sample.trim(3, 8);

		expect(trimmed).not.toBe(sample);
		expect(trimmed.format).toBe(sample.format);
		expect(trimmed.sampleRate).toBe(SAMPLE_RATE);
		expect(trimmed.numberOfChannels).toBe(NUM_CHANNELS);
		expect(trimmed.numberOfFrames).toBe(5);
		expect(trimmed.duration).toBeCloseTo(5 / SAMPLE_RATE);
		expect(trimmed.timestamp).toBeCloseTo(TIMESTAMP + 3 / SAMPLE_RATE);

		// The trimmed frame i corresponds to the original frame i + 3
		for (let f = 0; f < trimmed.numberOfFrames; f++) {
			for (let c = 0; c < NUM_CHANNELS; c++) {
				expect(readCell(trimmed, f, c)).toBe(cellValue(f + 3, c));
			}
		}

		// The original sample must be untouched
		expect(sample.numberOfFrames).toBe(NUM_FRAMES);
		expect(readCell(sample, 3, 0)).toBe(cellValue(3, 0));
	});

	test(`trim, full range is an independent copy (${label})`, () => {
		using sample = makeSample();
		using trimmed = sample.trim(0, NUM_FRAMES);

		expect(trimmed.numberOfFrames).toBe(NUM_FRAMES);
		expect(trimmed.timestamp).toBeCloseTo(TIMESTAMP);
		for (let f = 0; f < NUM_FRAMES; f++) {
			for (let c = 0; c < NUM_CHANNELS; c++) {
				expect(readCell(trimmed, f, c)).toBe(cellValue(f, c));
			}
		}
	});

	test(`trim, pathological zero-sample case (${label})`, () => {
		using sample = makeSample();

		// Empty range in the middle
		using empty = sample.trim(4, 4);
		expect(empty.numberOfFrames).toBe(0);
		expect(empty.duration).toBe(0);
		expect(empty.format).toBe(sample.format);
		expect(empty.numberOfChannels).toBe(NUM_CHANNELS);
		expect(empty.timestamp).toBeCloseTo(TIMESTAMP + 4 / SAMPLE_RATE);

		// Empty range right at the end (startSample === numberOfFrames) is still valid
		using emptyAtEnd = sample.trim(NUM_FRAMES, NUM_FRAMES);
		expect(emptyAtEnd.numberOfFrames).toBe(0);
		expect(emptyAtEnd.timestamp).toBeCloseTo(TIMESTAMP + NUM_FRAMES / SAMPLE_RATE);
	});

	test(`trim, illegal params (${label})`, () => {
		using sample = makeSample();

		// Non-integer
		expect(() => sample.trim(1.5, 5)).toThrow(TypeError);
		expect(() => sample.trim(1, 5.5)).toThrow(TypeError);

		// Negative
		expect(() => sample.trim(-1, 5)).toThrow(TypeError);
		expect(() => sample.trim(0, -1)).toThrow(TypeError);

		// Out of range
		expect(() => sample.trim(0, NUM_FRAMES + 1)).toThrow(RangeError);
		expect(() => sample.trim(NUM_FRAMES + 1, NUM_FRAMES + 1)).toThrow(RangeError);

		// End before start
		expect(() => sample.trim(6, 3)).toThrow(RangeError);
	});
}

test('trim, throws on a closed sample', () => {
	const sample = makeInterleavedSample();
	sample.close();
	expect(() => sample.trim(0, 5)).toThrow('AudioSample is closed.');
});

test('copyTo, AudioData-backed, planar destination falls back to manual conversion', () => {
	withMockedNativeCopyTo((calls) => {
		using sample = makeAudioDataBackedSample();

		for (let c = 0; c < NUM_CHANNELS; c++) {
			const out = new Int16Array(NUM_FRAMES);
			sample.copyTo(out, { planeIndex: c, format: 's16-planar' });

			for (let f = 0; f < NUM_FRAMES; f++) {
				expect(out[f]).toBe(cellValue(f, c));
			}
		}

		// With a frame offset
		const out = new Int16Array(NUM_FRAMES - 3);
		sample.copyTo(out, { planeIndex: 1, format: 's16-planar', frameOffset: 3 });
		for (let f = 0; f < NUM_FRAMES - 3; f++) {
			expect(out[f]).toBe(cellValue(f + 3, 1));
		}

		// The native conversion must have been attempted (and thrown)
		expect(calls.some(options => options.format === 's16-planar')).toBe(true);
	});
});

test('copyTo, AudioData-backed, interleaved destination falls back to manual conversion', () => {
	withMockedNativeCopyTo((calls) => {
		using sample = makeAudioDataBackedSample();

		const out = new Float32Array(NUM_FRAMES * NUM_CHANNELS);
		sample.copyTo(out, { planeIndex: 0, format: 'f32' });

		for (let f = 0; f < NUM_FRAMES; f++) {
			for (let c = 0; c < NUM_CHANNELS; c++) {
				expect(out[f * NUM_CHANNELS + c]).toBe(Math.fround(cellValue(f, c) / 32767));
			}
		}

		// The native conversion must have been attempted (and thrown)
		expect(calls.some(options => options.format === 'f32')).toBe(true);
	});
});

test('copyTo, AudioData-backed, control case with native format conversion', () => {
	using sample = makeAudioDataBackedSample();

	for (let c = 0; c < NUM_CHANNELS; c++) {
		const out = new Int16Array(NUM_FRAMES);
		sample.copyTo(out, { planeIndex: c, format: 's16-planar' });

		for (let f = 0; f < NUM_FRAMES; f++) {
			// Allow off-by-one
			expect(Math.abs(out[f]! - cellValue(f, c))).toBeLessThanOrEqual(1);
		}
	}

	const out = new Float32Array(NUM_FRAMES * NUM_CHANNELS);
	sample.copyTo(out, { planeIndex: 0, format: 'f32' });

	for (let f = 0; f < NUM_FRAMES; f++) {
		for (let c = 0; c < NUM_CHANNELS; c++) {
			expect(out[f * NUM_CHANNELS + c]).toBe(Math.fround(cellValue(f, c) / 32767));
		}
	}
});

const withMockedNativeCopyTo = (fn: (calls: AudioDataCopyToOptions[]) => void) => {
	// eslint-disable-next-line @typescript-eslint/unbound-method
	const original = AudioData.prototype.copyTo;
	const calls: AudioDataCopyToOptions[] = [];

	AudioData.prototype.copyTo = function (this: AudioData, destination, options) {
		calls.push(options);
		if (options.format !== undefined && options.format !== 'f32-planar') {
			throw new DOMException('Format conversion not supported.', 'NotSupportedError');
		}

		return original.call(this, destination, options);
	};

	try {
		fn(calls);
	} finally {
		AudioData.prototype.copyTo = original;
	}
};

const makeAudioDataBackedSample = () => {
	const data = new Float32Array(NUM_FRAMES * NUM_CHANNELS);
	for (let f = 0; f < NUM_FRAMES; f++) {
		for (let c = 0; c < NUM_CHANNELS; c++) {
			data[f * NUM_CHANNELS + c] = cellValue(f, c) / 32767;
		}
	}

	return new AudioSample(new AudioData({
		format: 'f32',
		sampleRate: SAMPLE_RATE,
		numberOfFrames: NUM_FRAMES,
		numberOfChannels: NUM_CHANNELS,
		timestamp: TIMESTAMP * 1e6,
		data,
	}));
};