74 lines
2.6 KiB
TypeScript
74 lines
2.6 KiB
TypeScript
import { describe, expect, it } from 'vitest'
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import { toFloat32FromPCM16, toPCM16FromFloat32, toWav, toWavFromPCM16 } from './wav'
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describe('pcm sample encoding', () => {
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it('converts normalized Float32 samples to little-endian PCM16 bytes', () => {
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const samples = new Float32Array([-2, -1, -0.5, 0, 0.5, 1, 2])
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const pcmBytes = toPCM16FromFloat32(samples)
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const view = new DataView(pcmBytes.buffer, pcmBytes.byteOffset, pcmBytes.byteLength)
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expect(view.getInt16(0, true)).toBe(-32768)
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expect(view.getInt16(2, true)).toBe(-32768)
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expect(view.getInt16(4, true)).toBe(-16384)
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expect(view.getInt16(6, true)).toBe(0)
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expect(view.getInt16(8, true)).toBe(16383)
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expect(view.getInt16(10, true)).toBe(32767)
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expect(view.getInt16(12, true)).toBe(32767)
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})
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it('converts little-endian PCM16 bytes to normalized Float32 samples', () => {
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const pcmBytes = new Uint8Array(10)
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const view = new DataView(pcmBytes.buffer)
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view.setInt16(0, -32768, true)
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view.setInt16(2, -16384, true)
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view.setInt16(4, 0, true)
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view.setInt16(6, 16384, true)
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view.setInt16(8, 32767, true)
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expect([...toFloat32FromPCM16(pcmBytes)]).toEqual([
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-1,
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-0.5,
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0,
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0.5,
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32767 / 32768,
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])
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})
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it('rejects incomplete PCM16 samples', () => {
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expect(() => toFloat32FromPCM16(new Uint8Array([0]))).toThrow(
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'PCM16 input must contain complete 16-bit samples.',
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)
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})
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})
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describe('toWav', () => {
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it('converts Float32 samples to PCM16 bytes by default', () => {
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const samples = new Float32Array([-1, 0, 1])
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const wav = toWav(samples.buffer, 24000)
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const view = new DataView(wav)
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expect(view.getInt16(44, true)).toBe(-32768)
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expect(view.getInt16(46, true)).toBe(0)
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expect(view.getInt16(48, true)).toBe(32767)
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})
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it('preserves PCM16 bytes and writes the WAV metadata', () => {
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const pcmBytes = new Uint8Array([0x00, 0x80, 0xFF, 0x7F])
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const wav = toWavFromPCM16(pcmBytes, 24000)
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const view = new DataView(wav)
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expect(new TextDecoder().decode(new Uint8Array(wav, 0, 4))).toBe('RIFF')
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expect(view.getUint32(4, true)).toBe(40)
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expect(new TextDecoder().decode(new Uint8Array(wav, 8, 4))).toBe('WAVE')
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expect(view.getUint16(20, true)).toBe(1)
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expect(view.getUint16(22, true)).toBe(1)
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expect(view.getUint32(24, true)).toBe(24000)
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expect(view.getUint32(28, true)).toBe(48000)
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expect(view.getUint16(32, true)).toBe(2)
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expect(view.getUint16(34, true)).toBe(16)
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expect(view.getUint32(40, true)).toBe(pcmBytes.byteLength)
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expect([...new Uint8Array(wav, 44)]).toEqual([...pcmBytes])
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})
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})
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