Refactor to worker version

src/worker-script/browser/.eslintrc

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+{
+  "env": {
+    "worker": true
+  }
+}

src/worker-script/browser/getCore.js

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+module.exports = (corePath) => {
+  if (typeof global.Module === 'undefined') {
+    global.importScripts(corePath);
+  }
+  return global.Module;
+};

src/worker-script/browser/index.js

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+const worker = require('../');
+const getCore = require('./getCore');
+
+global.addEventListener('message', ({ data }) => {
+  worker.dispatchHandlers(data, (obj) => postMessage(obj));
+});
+
+worker.setAdapter({
+  getCore,
+});

src/worker-script/constants/defaultArgs.js

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+module.exports = [
+  './ffmpeg', // args[0] is always binary path
+  '-nostdin', // Disable interaction mode
+  '-loglevel',
+  'quiet',
+];

src/worker-script/index.js

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+require('regenerator-runtime/runtime');
+const defaultArgs = require('./constants/defaultArgs');
+
+let Module = null;
+let adapter = null;
+let ffmpeg = null;
+
+const str2ptr = (s) => {
+  const ptr = Module._malloc((s.length + 1) * Uint8Array.BYTES_PER_ELEMENT);
+  for (let i = 0; i < s.length; i += 1) {
+    Module.setValue(ptr + i, s.charCodeAt(i), 'i8');
+  }
+  Module.setValue(ptr + s.length, 0, 'i8');
+  return ptr;
+};
+
+const strList2ptr = (strList) => {
+  const listPtr = Module._malloc(strList.length * Uint32Array.BYTES_PER_ELEMENT);
+
+  strList.forEach((s, idx) => {
+    const strPtr = str2ptr(s);
+    Module.setValue(listPtr + (4 * idx), strPtr, 'i32');
+  });
+
+  return listPtr;
+};
+
+const load = ({ payload: { options: { corePath } } }, res) => {
+  if (Module == null) {
+    const Core = adapter.getCore(corePath);
+    Core()
+      .then((_Module) => {
+        Module = _Module;
+        ffmpeg = Module.cwrap('ffmpeg', 'number', ['number', 'number']);
+        res.resolve(true);
+      });
+  } else {
+    res.resolve(true);
+  }
+};
+
+const transcode = ({
+  payload: {
+    media,
+    outputExt,
+    options = '',
+  },
+}, res) => {
+  const data = Uint8Array.from({ ...media, length: Object.keys(media).length });
+  const iPath = 'media';
+  const oPath = `media.${outputExt}`;
+  const args = [...defaultArgs, ...`${options} -i ${iPath} ${oPath}`.trim().split(' ')];
+  Module.FS.writeFile(iPath, data);
+  ffmpeg(args.length, strList2ptr(args));
+  res.resolve(Module.FS.readFile(oPath));
+};
+
+exports.dispatchHandlers = (packet, send) => {
+  const res = (status, data) => {
+    send({
+      ...packet,
+      status,
+      data,
+    });
+  };
+  res.resolve = res.bind(this, 'resolve');
+  res.reject = res.bind(this, 'reject');
+  res.progress = res.bind(this, 'progress');
+
+  try {
+    ({
+      load,
+      transcode,
+    })[packet.action](packet, res);
+  } catch (err) {
+    /** Prepare exception to travel through postMessage */
+    res.reject(err.toString());
+  }
+};
+
+exports.setAdapter = (_adapter) => {
+  adapter = _adapter;
+};

src/worker-script/node/getCore.js

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+let FFmpegCore = null;
+
+module.exports = () => {
+  if (FFmpegCore === null) {
+    FFmpegCore = require('@ffmpeg/core');
+  }
+  return FFmpegCore;
+};

src/worker-script/node/index.js

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+const worker = require('../');
+const getCore = require('./getCore');
+
+process.on('message', (packet) => {
+  worker.dispatchHandlers(packet, (obj) => process.send(obj));
+});
+
+worker.setAdapter({
+  getCore,
+});