Hd? Hd HD
High-definition TV, high-definition equipment, high-definition format, high-definition movies.
BD？ Blue light? CD? Blu-ray disc
It is one of the next generation optical disc formats after DVD, which is used to store high-quality audio and video and large-capacity data storage.
Extended data:
High-definition movies are short for high-definition TV, which means "high-definition TV" when translated into Chinese. HDTV technology originated from DTV (Digital Television) technology.
Both HDTV technology and DTV technology use digital signals, and HDTV technology belongs to the highest standard of DTV and has the best video and audio effects. HDTV is different from the traditional TV system which adopts analog signal transmission at present. HDTV uses digital signal transmission.
High-definition movies do not refer to movies that can be seen clearly, but a video name transmitted by digital signals, including formats: 480p, 720p, 1080p.
Blu-ray disc is named after reading and writing with blue-violet laser with wavelength of 405nm (nanometer) (DVD disc uses red laser with wavelength of 650nm for reading and writing, and CD disc uses near-infrared invisible laser with wavelength of 780nm for reading and writing data).
The single-layer Blu-ray disc has a capacity of 25 or 27GB, which is enough to record high-resolution movies for up to 4 hours. On February 19, 2008, Toshiba, the leader of HD DVD, announced that it would withdraw from all HD DVD-related businesses at the end of March.
The dispute over the format of the next-generation optical disc, which lasted for many years, officially came to an end, and finally the Blu-ray disc headed by Sony won. Blu-ray disc uses YCbCr color and space, adopts 4:2:0 chroma subsampling, and the color depth is 8bit.
Blu-ray discs are read and written by a blue-violet laser with a wavelength of 405 nm. The reason why it can store huge capacity is mainly because of these three writing methods:
1. Reduce the laser spot to shorten the track distance (0.32μm) and increase the capacity. The pits of 0 and 1 digital data (0. 15 micron) formed by Blu-ray disc are much smaller than those of traditional DVD and CD discs, because the wavelength of blue-violet laser is shorter and the focal diameter after focusing is smaller.
Secondly, multi-layer writing effect is achieved by using different reflectivity.
Thirdly, the groove track parallel writing method increases the recording space. The high storage capacity of blue light comes from increasing the wavelength of laser light source and (405nm) objective lens numerical aperture mirror (0.85).
References:
Baidu Encyclopedia-HD Movie Baidu Encyclopedia-Blu-ray Disc