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
Picture disc from the late 1940s through the 1950s. Their most popular and well-known issues resembled Vogue records in their general style of illustration and use of high-quality materials, but they were only 7 inches in diameter, had no reinforcing core disc, and sold for a much lower price. Other companies such as Voco also made picture discs for children. Red Raven Movie Records, introduced in 1956, were a very unusual type of children's picture disc. They featured a sequence of sixteen interwoven animation frames arrayed around the center and were to be played at 78 rpm on a turntable with a