Finding the length of an mp3 file
You can also get this using eyed3, if that's your flavor by doing:
import eyed3duration = eyed3.load('path_to_your_file.mp3').info.time_secsNote however that this uses sampling to determine the length of the track. As a result, if it uses variable bit rate, the samples may not be representative of the whole, and the estimate may be off by a good degree (I've seen these estimates be off by more than 30% on court recordings).
I'm not sure that's much worse than other options, but it's something to remember if you have variable bit rates.