DVD glossary

Header

Area appended to and preceding user data containing addressing, format, and other information.

HF

Analog signals containing High Frequency data information in contrast to low frequency servo information.

HFS

Hierarchical File Structure defining the native Apple MacIntosh format for mass storage.

High Sierra

Draft version of ISO 9660 (MS-DOS) standard for volume and file structure. Named for the Lake Tahoe, California hotel that hosted the conference resulting in the draft standard.

Holography

Recording of both amplitude and phase information of an object using interference between an object wave and a coherent reference wave, both incident on a photo sensitive medium. Coherent illumination of this medium, upon wavefront reconstruction, results in an image having both amplitude and phase characteristics of the original, resulting in three dimensional and other special properties.

Huygens' Principal

Qualitative explanation of diffraction stating that the propagation of a light wave can be predicted by assuming that each point of the wave front acts as the source of a secondary wave that spreads out in all directions. The envelope of all the secondary waves is the new wave front. Precisely defined by the Fresnel-Kirchhoff formula.

Hybrid

Disc containing both an ISO 9660 (MS-DOS) partition and an HFS partition. Or, a disc containing both ISO 9660 and UDF volume and file structures. Or, may indicate that the first session of a multi- session CD-R or CD-RW disc is a mastered session followed by recorded sessions.

HDTV
High Definition Television encompasses both analog and digital televisions that have a 16:9 aspect ratio and approximately 5 times the resolution of standard TV (double vertical, double horizontal, wider aspect).

Horizontal Resolution
This is the number of lines that run across the width of a TV. You get the clearest picture with a larger number. The main breakdown is as follows:
   Standard VHS resolution - 220 horizontal lines
   Laser disc - 425 horizontal line
   DVD - 480-500 horizontal line

Hue
Color.