Turok 2: Seed Of Evil – Looped – YouTube (http://www.youtube.com/playlist?list=PLJhiEexUreA9vD5-F_QXD8lFKCtuEdaBX)
Have fun listening.
This is because each channel of the audio (i.e. track) is a different length.
Think polyrhythms.
If it’s just two tracks, one might be 25 seconds, the other might be 27 seconds.
Individually, they may be short, but together, it would take exactly 675 seconds (or 11 minutes and 15 seconds) for them to both start at the same point again. This can also be demonstrated visually…
6 seconds might look like this |—–
7 seconds might look like this /——
Put them together… you’d get |—–|/—-|-/—|–/–|—/-|—-/|—–|
But then, if there’s more than two tracks it’s more complicated… let’s say there are 4 tracks 4, 5, 6, and 7 seconds long respectively.
+ = 4, o = 5, x = 6, / = 7
+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—
o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-o—-
x—–x—–x—–x—–x—–x—–x—–x—–x—–x—–x—–x—–x—–x—–x—–x—–x—–x
/——/——/——/——/——/——/——/——/——/——/——/——/——/——/——
That represents 96 seconds (1:36). As you can see, the 1st, 2nd and 4th tracks are aligned after this time, but the 3rd track is one second ahead, which means it’s still not fully looped. In this case, the loop is 420 seconds (or exactly 7 minutes). See how just a few seconds can be very long when the tracks are different?
This is done in a lot of stuff. Oblivion, a lot of Game Boy Camera music, the Menu theme from Super Smash Bros, etc.