Quality of the player, quality of the disc, type of the disc, format the
disc was created in...all of these are factors that may cause a DVD player not to play a disc. It is also possible that the disc itself may be
perfectly readable but contains nothing the DVD player can play back.
Most players today will play DVD+R, others DVD-R. Some may not play DVD+RW or DVD-R or DVD+R. If it is an old player then it may not play. Certain brands is less likely to than others.
As for different colors, I believe it indicates the type or composition of the disc you have. However, there is probably no way to absolutely determine what type of DVD or CD you are dealing with by just looking at the bottom of the disc. DVD+R discs, for example, are a different color than DVD+RW discs. IIRC dual layer discs look different on the bottom side than single layer ones.
Last update: 05:44 PM Saturday, February 4, 2006