What is the transfer rate of the DVD?
Since a DVD was initially designed to store and playback movies, it was determined that the transfer rate of 1350 KB/sec would provide the best playback quality. This speed, which is about 9X CD-ROM reading speed, is designated as 1X in DVD. Before data is being stored on DVD, the increase in DVD reading speed can only increase the risk of poor playback quality utilizing discs that are NOT perfect. DVD-ROM drives are able to determine if user is watching movies or transferring data, and set the transfer rate accordingly to maximize drive's efficiency.