I'm currently trying to create a music player, but I need the song's length. How would I get that? I've searched on the wiki and I really haven't found anything.
Once you load a song into your game, you can easily obtain it's 'song length' through a property of Sound.
As shown on the Roblox wiki Sound API page, there is a property called TimeLength:
TimeLength [readonly]
The length of the sound in seconds. If the sound is not loaded, this value will be 0.
In script form, you'll have something similar to the bellow code:
local Sound = Instance.new("Sound", game.Workspace) Sound.SoundId = ... -- Your content Id print(Sound.TimeLenght) -- prints the length in seconds
Remember, TimeLength is readonly meaning you cannot change this value! If you want to play a song at a specific time, you would have to edit the TimePosition property.