Blu-ray Disc (BD)

This optical disk, designed for HD, can hold 25 GB on a single-layer CD-sized (12cm) disk using 405 nanometer blue-violet lasers. Dual layer disks hold up to 50 GB. Also available are triple layer (100 GB) and quadruple layer (128 GB) disks, which may accommodate 4K UHD video. The companies that established the basic specifications were: Hitachi Ltd., LG Electronics Inc., Matsushita Electric Industrial Co. Ltd., Pioneer Corporation, Royal Philips Electronics, Samsung Electronics Co. Ltd., Sharp Corporation, Sony Corporation, and Thomson Multimedia.

Players must be able to decode MPEG-2, H.264/AVC (MPEG-4 part 10) and SMPTE VC-1 coded material. MPEG-2 offers backward compatibility for DVDs while the other two more modern codecs are at least 50 percent more efficient, using less disk space or producing higher quality results. Audio codecs supported are Linear PCM, Dolby Digital, Dolby Digital Plus, Dolby TrueHD, DTS Digital Surround, DTS-HD.

The baseline data rate is 36 Mb/s – giving over one-and-a-half hours recording of HD material on a single layer, or about 13 hours of SD. For Blu-ray Disc movies (BD-ROM) the maximum transfer rate is 54 Mb/s for audio and video, with a maximum of 40 Mb/s for video. Random access allows easy video editing and simultaneous record and playback.

Ultra HD Blu-ray is the 4K Blu-ray format, expected for delivery Christmas 2015. Handling 4K UHD video at up to 60 f/s, the specification includes HEVC (H.265) video compression, a wider color gamut (than HD) as well as High Dynamic Range (HDR) and 10-bit video sampling. Disc capacities are set at 66 GB (dual layer) and 100 GB (triple layer). The system will also be able to play legacy standards including Blu-ray, DVD and CD. The final specification is expected in mid-2015.

See also: DVD, HD DVD, Optical disks, Professional Disc