I have a CD that was provided to me with audio auditions for a voiceover. I put the Cd in the CD drive on my computer but nothing played. What's the difference between a CD that plays in your computer vs.the cd player in for instance, a stereo? Would the files need to be Mp3 in order to extract them from the CD and forward them on email? What other types of files can I expect? For example, if a talent provides me with an audition CD. How do I tell what I've got? What's the differnece?