小弟在Blue-ray Disc官方網站的FAQ裡面有看到類似向下相容的問題，我想應該是有相容DVD/CD~
以下是官網裡面的內容:
2.4 Will Blu-ray support playback of DVDs?


Yes, several leading consumer electronics companies (including Sony, Panasonic, Philips, Samsung and LG) have already demonstrated products that can read/write CDs, DVDs and Blu-ray discs using a BD/DVD/CD compatible optical head, so you don't have to worry about your existing DVD collection becoming obsolete. Although it's up to each manufacturer to decide if they want to make their products backwards compatible with DVD, the format is far too popular to not be supported. The Blu-ray Disc Association (BDA) expects every Blu-ray Disc device to be backward compatible with CDs and DVDs.
http://www.blu-ray.com/faq/#2.4