formatTimecode function
Implementation
String formatTimecode(Duration d) {
final m = d.inMinutes.remainder(60).toString().padLeft(2, '0');
final s = d.inSeconds.remainder(60).toString().padLeft(2, '0');
final h = d.inHours;
return h > 0 ? '$h:$m:$s' : '$m:$s';
}