Init commit

src/constants/defaultArgs.js

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

src/index.js

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+const load = require('./load');
+const transcode = require('./transcode');
+
+module.exports = {
+  load,
+  transcode,
+};

src/load.js

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+const { setModule } = require('./util/module');
+const FFmpegCore = require('@ffmpeg/core');
+
+module.exports = () => (
+  new Promise((resolve, reject) => {
+    FFmpegCore()
+      .then((Module) => {
+        setModule(Module);
+        resolve();
+      });
+  })
+);

src/transcode.js

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+const fs = require('fs');
+const { getModule } = require('./util/module');
+const getFFmpeg = require('./util/getFFmpeg');
+const strList2ptr = require('./util/strList2ptr');
+const defaultArgs = require('./constants/defaultArgs');
+
+module.exports = (inputPath, outputExt, options='') => {
+  const Module = getModule();
+  const data = new Uint8Array(fs.readFileSync(inputPath));
+  const iPath = `file.${inputPath.split('.').pop()}`;
+  const oPath = `file.${outputExt}`;
+  const ffmpeg = getFFmpeg();
+  const args = [...defaultArgs, ...`${options} -i ${iPath} ${oPath}`.trim().split(' ')];
+  Module.FS.writeFile(iPath, data);
+  ffmpeg(args.length, strList2ptr(args));
+  return Buffer.from(Module.FS.readFile(oPath));
+};

src/util/getFFmpeg.js

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+const { getModule } = require('./module');
+
+module.exports = () => {
+  const Module = getModule();
+  return Module.cwrap('ffmpeg', 'number', ['number', 'number']);
+};

src/util/module.js

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+let Module = null;
+
+exports.setModule = m => {
+  Module = m;
+};
+
+exports.getModule = () => Module;

src/util/str2ptr.js

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+const { getModule } = require('./module');
+
+module.exports = (s) => {
+  const Module = getModule();
+  const ptr = Module._malloc((s.length+1)*Uint8Array.BYTES_PER_ELEMENT);
+  for (let i = 0; i < s.length; i++) {
+    Module.setValue(ptr+i, s.charCodeAt(i), 'i8');
+  }
+  Module.setValue(ptr+s.length, 0, 'i8');
+  return ptr;
+};

src/util/strList2ptr.js

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+const { getModule } = require('./module');
+const str2ptr = require('./str2ptr');
+
+module.exports = (strList) => {
+  const Module = getModule();
+  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;
+};