如何上传mp3文件并在laravel 4.2中获取其持续时间

I'd like to upload a MP3 file in Laravel and then get the duration of the MP3. Here's my code, but it's not working:

$music_file = Input::file('audio_path');
$file_music = date('Y-m-d-H-i-s')."-".$music_file->getClientOriginalName();
$path = public_path('assets/music/' . $file_music);
$path = $music_file->getRealPath();

for moving MP3

$music_file = Input::file('audio_path');
$file_music = date('Y-m-d-H-i-s')."-".$music_file->getClientOriginalName();
$path = public_path('assets/music/' . $file_music);
$music_file->move($path,$file_music);