How to Build a Mp4 To Mov Converter

// Using FFmpeg (Node.js child process or WASM)
import { exec } from 'child_process';

function convertMP4toMOV(inputPath, outputPath, options = {}) {
  const {
    codec = 'copy', // 'copy' for remux, 'libx264' for transcode
    quality = 23,    // CRF value for transcoding
  } = options;

  const command = codec === 'copy'
    ? `ffmpeg -i "${inputPath}" -c copy "${outputPath}"`
    : `ffmpeg -i "${inputPath}" -c:v libx264 -crf ${quality} -c:a aac "${outputPath}"`;

  return new Promise((resolve, reject) => {
    exec(command, (error, stdout, stderr) => {
      if (error) reject(error);
      else resolve({ output: outputPath, stderr });
    });
  });
}

// Browser-based using FFmpeg WASM
async function convertInBrowser(file) {
  const { createFFmpeg, fetchFile } = FFmpeg;
  const ffmpeg = createFFmpeg({ log: true });
  await ffmpeg.load();

  ffmpeg.FS('writeFile', 'input.mp4', await fetchFile(file));
  await ffmpeg.run('-i', 'input.mp4', '-c', 'copy', 'output.mov');

  const data = ffmpeg.FS('readFile', 'output.mov');
  return new Blob([data.buffer], { type: 'video/quicktime' });
}