Optical disc the DataPlay format, can have capacity comparable to that of the larger, standard compact 12 cm disc. Third-generation optical discs are in development, meant for distributing high-definition video and support greater data storage capacities, accomplished with short-wavelength visible-light lasers and greater numerical apertures. Blu-ray Disc and HD DVD uses blue-violet lasers and focusing optics of greater aperture, for use with discs with smaller pits and lands, thereby greater data storage capacity per layer. In practice, the effective multimedia presentation capacity is improved with enhanced video data compression codecs such as H.264/MPEG-4 AVC and VC-1. The following formats go beyond the
Track (optical disc) a "Sequential Recording Range Information" (SRRI) field of a "Disc Management Area" (DMA). Sessions contain logical tracks, which can be split to create new tracks. A final, "invisible" session holds free space in a single logical track, called the invisible/incomplete track. When a disc is finalized or closed, the latest information in the temporary DMAs such as SRRI is taken and copied into the DMA. Track (optical disc) On an optical disc, a track (CD) or title (DVD) is a subdivision of its content. Specifically, it is a consecutive set of "sectors" (called "timecode frames" on audio tracks) on the