Seven Segment Display Trouble

[SideA]

Hi there,

I am working on a project where I am hacking a portable CD player. My hang up: I need to decode a periodic digital signal which produces the one's digit of the track number display. I have found the two terminals (not including ground) that hold the digital signal. One of the terminals controls 4 of the 7 segments while the other terminal controls the remaining 3 segments. I really have no experience with decoding digital signals. Is there a way to decode the periodic signal such that it produces seven logic signals that correspond to their respective segments? Also if it helps, after looking at one of the two terminals with a scope I made some discoveries. If none of the segments are lit up, the scope can't read a signal to trigger. On the other extreme, if all the segments are lit up the output is a periodic signal that starts off low and is followed by a high signal. If any combination of on and off segments occurs, the output is a periodic step function that starts off low and is followed by a signal unique to the display output. Could anyone possibly help me out with this?

Sincerely,
-Scott