cranes: update with reverse playback + 4x speed

[dndrks]

speed options for buffer 2 now include: {-2.0, -1.0, -0.5, -0.25, 0.25, 0.5, 1.0, 2.0, 4.0} buffer 1 still: {0.25, 0.5, 1.0, 2.0}