What is the video quality of a copied DVD?

If you do not compress the video, the video quality of a copied DVD movie remains the same as the original DVD movie. You only need to compress the video when your original source DVD content cannot fit onto your blank disc; for example when you try to copy a Double-Layer DVD movie onto a Single-Layer DVD disc. In cases where you compress a video and the source DVD video size does not exceed 6 GB, you will not notice an obvious difference in the video quality. If the source DVD video size is more than 7GB, you might see some reduction in video quality. You can reduce the source video size by removing unwanted DVD content.