H/DTV
High-definition/digital television. A combination of acronyms that refers to both HDTV and DTV systems.

Half D1
An MPEG-2 video encoding mode in which half the horizontal resolution is sampled (352x480 for NTSC, 352x576 for PAL).

HAVi
A consumer electronics industry standard for interoperability between digital audio and video devices connected via a network in the consumer's home.

HDCD
High-definition Compatible Digital. A proprietary method of enhancing audio on CDs.

HDTV
High-definition television. A video format with a resolution approximately twice that of conventional television in both the horizontal and vertical dimensions, and a picture aspect ratio of 16:9. Used loosely to refer to the U.S. DTV System. Contrast with EDTV and IDTV.

hexadecimal
Representation of numbers using base 16.

HFS
Hierarchical file system. A file system used by Apple Computer's Mac OS operating system.

Highlight Information (HLI)
This is used to specify button highlights for menus. HLI contains information on the button number, highlight timing, palette for sub-picture highlights, coordinates of the button, etc.

High Sierra
The original file system standard developed for CD-ROM, later modified and adopted as ISO 9660.

horizontal resolution
See lines of horizontal resolution.

HQ-VCD
High-quality Video Compact Disc. Developed by the Video CD Consortium (Philips, Sony, Matsushita and JVC) as a successor to VCD. Evolved into SVCD.

HRRA
Home Recording Rights Association.

HTML
Hypertext markup language. A tagging specification, based on SGML (standard generalized markup language), for formatting text to be transmitted over the Internet and displayed by client software.

hue
The color of light or of a pixel. The property of color determined by the dominant wavelength of light.

Huffman coding
A lossless compression technique of assigning variable-length codes to a known set of values. Values occurring most frequently are assigned the shortest codes. MPEG uses a variation of Huffman coding with fixed code tables, often called variable-length coding (VLC).

Hz
Hertz. A unit of frequency measurement. The number of cycles (repetitions) per second.