files:
A (length 6)
B (length 3)
C (length 2)
metadata has length 1 for each track
buffer of length 5
playlist: ABC
*: current playing position
+: currently buffering
(): played buffers, not needed anymore
M is metadata
-- | -- | -- | -- | -- |
*A1*| A2 | A3 | A4 | AM | - buffer fills
(A1)|(A2)|(A3)|*A4*| AM | - A1-A3 are played
A6 | AM | BM |*A4*| A5 | - AM is moved to end, A5-A6 are buffered, BM is buffered
*A6*| AM | BM |(A4)|(A5)| - A4-A5 are played
*A6*| AM | B1 | B2 | BM | - BM is moved to end, B1-B2 are buffered
(A6)|(AM)|(B1)|*B2*| BM | - A6, B1 are played
BM | C1 | CM |*B2*| B3 | - BM is moved, B3, C1 and CM are buffered
(BM)|*C1*| CM |(B2)|(B3)| - B2-B3 are played
(BM)|*C1*| C2 | CM | -- | - CM is moved, C2 is buffered
-- | -- | -- | -- | -- |
*A1*|+A2+|+A3+|+A4+|+AM+| - buffer fills
(A1)|(A2)|(A3)|*A4*| AM | - A1-A3 have played
+A5+|+A6+|+BM+|*A4*| AM | - A5-A6 are buffered, BM is buffered
*A5*| A6 | BM |(A4)|(A5)| - A5-A6 are played
(A5)|*A6*| BM |+B1+|+B2+| - A6 playing, BM, B1-B2 buffering
(A5)|(A6)| BM | B1 |*B2*| - B1 - B2 playing
+B3+|+CM+| BM |(B1)|*B2*| - B2 playing, B3, CM buffering
*B3*| CM |+C1+|+C2+| -- | - B2 playing, C1, C2 buffering
(B3)| CM |*C1*| C2 | -- | - C1 playing