@thi.ng/dsp-io-wav/write.js

WAV file format generation

import { f32u16, f32u24, f32u32, f32u8 } from "@thi.ng/binary/float";
import { assert } from "@thi.ng/errors/assert";
import {
  asBytes,
  bytes,
  u16,
  u24,
  u32,
  u8
} from "@thi.ng/transducers-binary/bytes";
import { comp } from "@thi.ng/transducers/comp";
import { concat } from "@thi.ng/transducers/concat";
import { iterator } from "@thi.ng/transducers/iterator";
import { map } from "@thi.ng/transducers/map";
import { reduce } from "@thi.ng/transducers/reduce";
import { take } from "@thi.ng/transducers/take";
const HEADER_SIZE = 44;
const CONVERTERS = {
  8: (x) => u8(f32u8(x)),
  16: (x) => u16(f32u16(x), true),
  24: (x) => u24(f32u24(x), true),
  32: (x) => u32(f32u32(x), true)
};
const wavHeader = (spec) => {
  const bytesPerSample = spec.bits >> 3;
  const blockAlign = spec.channels * bytesPerSample;
  const dataLength = spec.length * blockAlign;
  return [
    u32(1380533830, false),
    // 'RIFF'
    u32(dataLength + HEADER_SIZE - 8, true),
    // riff len
    u32(1463899717, false),
    // 'WAVE'
    u32(1718449184, false),
    // 'fmt '
    u32(16, true),
    // fmt len,
    u16(1, true),
    // audio format id
    u16(spec.channels, true),
    u32(spec.sampleRate, true),
    u32(spec.sampleRate * blockAlign, true),
    // byte rate
    u16(blockAlign, true),
    u16(spec.bits, true),
    u32(1684108385, false),
    // 'data'
    u32(dataLength, true)
  ];
};
const wavByteArray = (spec, src) => {
  const convert = CONVERTERS[spec.bits];
  assert(!!convert, `unsupported bits/sample: ${spec.bits}`);
  return reduce(
    bytes(),
    new Uint8Array(
      HEADER_SIZE + spec.length * spec.channels * (spec.bits >> 3)
    ),
    concat(
      wavHeader(spec),
      iterator(comp(take(spec.length * spec.channels), map(convert)), src)
    )
  );
};
const wavBytes = (spec, src) => {
  const convert = CONVERTERS[spec.bits];
  assert(!!convert, `unsupported bits/sample: ${spec.bits}`);
  return asBytes(
    concat(
      wavHeader(spec),
      iterator(comp(take(spec.length * spec.channels), map(convert)), src)
    )
  );
};
export {
  wavByteArray,
  wavBytes,
  wavHeader
};