compression-output-length.tentative.any.js

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// META: global=window,worker,shadowrealm

'use strict';

// This test asserts that compressed data length is shorter than the original

// data length. If the input is extremely small, the compressed data may be

// larger than the original data.

const LARGE_FILE = '/media/test-av-384k-44100Hz-1ch-320x240-30fps-10kfr.webm';

async function compressArrayBuffer(input, format) {

  const cs = new CompressionStream(format);

  const writer = cs.writable.getWriter();

  writer.write(input);

  const closePromise = writer.close();

  const out = [];

  const reader = cs.readable.getReader();

  let totalSize = 0;

  while (true) {

    const { value, done } = await reader.read();

    if (done)

      break;

    out.push(value);

    totalSize += value.byteLength;

  await closePromise;

  const concatenated = new Uint8Array(totalSize);

  let offset = 0;

  for (const array of out) {

    concatenated.set(array, offset);

    offset += array.byteLength;

  return concatenated;

promise_test(async () => {

  const response = await fetch(LARGE_FILE);

  const buffer = await response.arrayBuffer();

  const bufferView = new Uint8Array(buffer);

  const originalLength = bufferView.length;

  const compressedData = await compressArrayBuffer(bufferView, 'deflate');

  const compressedLength = compressedData.length;

  assert_less_than(compressedLength, originalLength, 'output should be smaller');

}, 'the length of deflated data should be shorter than that of the original data');

promise_test(async () => {

  const response = await fetch(LARGE_FILE);

  const buffer = await response.arrayBuffer();

  const bufferView = new Uint8Array(buffer);

  const originalLength = bufferView.length;

  const compressedData = await compressArrayBuffer(bufferView, 'gzip');

  const compressedLength = compressedData.length;

  assert_less_than(compressedLength, originalLength, 'output should be smaller');

}, 'the length of gzipped data should be shorter than that of the original data');

promise_test(async () => {

  const response = await fetch(LARGE_FILE);

  const buffer = await response.arrayBuffer();

  const bufferView = new Uint8Array(buffer);

  const originalLength = bufferView.length;

  const compressedData = await compressArrayBuffer(bufferView, 'deflate-raw');

  const compressedLength = compressedData.length;

  assert_less_than(compressedLength, originalLength, 'output should be smaller');

}, 'the length of deflated (with -raw) data should be shorter than that of the original data');