Why is `len(audio_segment)` return milliseconds, but every other operation use second?

For real I'm just confused, as I had a confusing bug and it turned out it was because `len(audio_segment)` returned milliseconds for some reason.

Okay after reviewing the your code... *sigh* I guess It make sense, but at least make a function that returns it in seconds and not "advertise" this inconsistency in your docs 😭 