Add util and rewrite examples (WIP)

apps/examples/node/multiple-output.js

@@ -0,0 +1,14 @@
+const fs = require('fs');
+const { createFFmpeg, fetchFile } = require('../../src');
+
+const ffmpeg = createFFmpeg({ log: true });
+
+(async () => {
+  await ffmpeg.load();
+  ffmpeg.FS('writeFile', 'flame.avi', await fetchFile('../assets/flame.avi'));
+  await ffmpeg.run('-i', 'flame.avi', '-map', '0:v', '-r', '25', 'out_%06d.bmp');
+  ffmpeg.FS('readdir', '/').filter((p) => p.endsWith('.bmp')).forEach(async (p) => {
+    fs.writeFileSync(p, ffmpeg.FS('readFile', p));
+  });
+  process.exit(0);
+})();