HD DVD had declined to say whether the 51 GB disc was compatible with existing drives and players. Specification 2.0 Part 1 (Physical Specification) for triple layer HD DVD had been approved in November 2007. At the CES 2007, Ritek revealed their high definition optical disc process that extended both competing high definition formats to ten layers, increasing capacity to 150 GB for HD DVD and 250 GB for Blu-ray Disc. A major obstacle to implementing this technology in either format (150 GB HD DVD will not be developed due to HD DVD's discontinuation) is that reader-writer technology available may not be
Compressed audio optical disc case and disc drive exposes the disc to dust, and also makes the disc liable to be damaged permanently. Also note that some CD and DVD discs also have defective aluminum layers that can flake, and damage the disc naturally. Repeated insertion and removal of optical discs can occur when somebody has to deal with multi-gigabyte collections which can span across as many as 10 CD-Rs (or 5 DVD-Rs) or even more when lots more gigabytes were to be used. Sometimes when somebody is looking for a specific MP3 or similar; it can result in insertion and removal if more