The tracks need to ripped off as Wav or mp3 to be compatible. Wav is the standard for commercial music cd's that will run in 'any' player. The mp3 format is compressed so as many more songs can be recorded to the CD. But it needs a player that's compat.
Best ripper/converter around in my experience is dBPower AMP . It's no longer free,but well worth the money imho...