2029070.html - mozsearch

Enable keyboard shortcuts

<!DOCTYPE html>

<html class="reftest-wait">

<script>

// LSB-first bit packer matching oggpack_write semantics.

class BitPacker {

  constructor() {

    this.bytes = [];

    this.cur = 0;

    this.bit = 0;

  write(val, bits) {

    for (let i = 0; i < bits; i++) {

      if (val & (1 << i)) this.cur |= (1 << this.bit);

      if (++this.bit === 8) {

        this.bytes.push(this.cur);

        this.cur = 0;

        this.bit = 0;

  finish() {

    if (this.bit > 0) this.bytes.push(this.cur);

    return new Uint8Array(this.bytes);

function ilog(v) {

  let r = 0;

  while (v) { r++; v >>>= 1; }

  return r;

const kIdHeader = new Uint8Array([

  0x01, 0x76, 0x6f, 0x72, 0x62, 0x69, 0x73, 0x00, 0x00, 0x00, 0x00, 0x01,

  0x80, 0xbb, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

  0x00, 0x00, 0x00, 0x00, 0x66, 0x01

]);

const kCommentHeader = new Uint8Array([

  0x03, 0x76, 0x6f, 0x72, 0x62, 0x69, 0x73, 0x00, 0x00, 0x00, 0x00, 0x00,

  0x00, 0x00, 0x00, 0x01

]);

// Build a Vorbis setup header with two codebooks:

//   Codebook 0: minimal valid (dim=1, entries=2)

//   Codebook 1: given dim/entries, ordered encoding, all entries used

function buildSetupHeader(dim, entries) {

  const p = new BitPacker();

  const magic = "vorbis";

  p.write(0x05, 8);

  for (let i = 0; i < 6; i++) p.write(magic.charCodeAt(i), 8);

  p.write(1, 8); // 2 codebooks

  // Codebook 0: minimal valid

  p.write(0x564342, 24);

  p.write(1, 16);  p.write(2, 24);

  p.write(0, 1);   p.write(0, 1);

  p.write(0, 5);   p.write(0, 5);

  p.write(1, 4);   p.write(0, 32); p.write(0, 32);

  p.write(0, 4);   p.write(0, 1);

  p.write(0, 1);   p.write(0, 1);

  // Codebook 1: large entry count, ordered

  const k = ilog(entries) - 1;

  p.write(0x564342, 24);

  p.write(dim, 16);

  p.write(entries, 24);

  p.write(1, 1);

  p.write(k, 5);

  p.write(entries, ilog(entries));

  p.write(0, 4);

  // Time, floor, residue, mapping, modes (minimal valid)

  p.write(0, 6); p.write(0, 16);

  p.write(0, 6); p.write(1, 16);

  p.write(0, 5); p.write(0, 4); p.write(0, 4);

  p.write(0, 6); p.write(0, 16);

  p.write(0, 24); p.write(0, 24); p.write(0, 24);

  p.write(0, 6); p.write(0, 8);

  p.write(0, 3); p.write(0, 1);

  p.write(0, 6); p.write(0, 16);

  p.write(0, 1); p.write(0, 1);

  p.write(0, 8); p.write(0, 8); p.write(0, 8);

  p.write(0, 6); p.write(0, 1);

  p.write(0, 16); p.write(0, 16); p.write(0, 8);

  p.write(1, 1);

  return p.finish();

function lace(n) {

  const r = [];

  while (n >= 255) { r.push(255); n -= 255; }

  r.push(n);

  return r;

function buildDescription(setupHeader) {

  const l0 = lace(kIdHeader.length), l1 = lace(kCommentHeader.length);

  const desc = new Uint8Array(

    1 + l0.length + l1.length +

    kIdHeader.length + kCommentHeader.length + setupHeader.length

);

  let o = 0;

  desc[o++] = 2;

  for (const b of l0) desc[o++] = b;

  for (const b of l1) desc[o++] = b;

  desc.set(kIdHeader, o); o += kIdHeader.length;

  desc.set(kCommentHeader, o); o += kCommentHeader.length;

  desc.set(setupHeader, o);

  return desc;

const cases = [

  [0,  1 << 23],          // 8388608:  ov_ilog 0+24=24

  [1,  (1 << 23) - 1],    // 8388607:  ov_ilog 1+23=24

  [2,  (1 << 22) - 1],    // 4194303:  ov_ilog 2+22=24

  [4,  (1 << 21) - 1],    // 2097151:  ov_ilog 3+21=24

  [8,  (1 << 20) - 1],    // 1048575:  ov_ilog 4+20=24

  [16, (1 << 19) - 1],    // 524287:   ov_ilog 5+19=24

  [32, (1 << 18) - 1],    // 262143:   ov_ilog 6+18=24

  [64, (1 << 17) - 1],    // 131071:   ov_ilog 7+17=24

];

let pending = cases.length;

function done() {

  if (--pending === 0) {

    document.documentElement.removeAttribute("class");

for (const [dim, entries] of cases) {

  const setup = buildSetupHeader(dim, entries);

  const desc = buildDescription(setup);

  const dec = new AudioDecoder({

    output: f => f.close(),

    error: () => done()

});

  dec.configure({

    codec: "vorbis",

    sampleRate: 48000,

    numberOfChannels: 1,

    description: desc

});

  dec.decode(new EncodedAudioChunk({

    type: "key",

    timestamp: 0,

    data: new Uint8Array([0, 0, 0, 0])

  }));

  dec.flush().then(() => done(), () => done());

</script>

</html>