HAVi (Home Audio/Video interoperability) A FireWire-based technology for controlling various components of a home-theater system as a single unit with one remote control. This “interoperability” is possible because the FireWire interface carries control data along with digital audio and video in the same cable.

harmonic distortion The production of spurious frequencies at multiples of the original frequency. A circuit amplifying a 1kHz sine wave will create frequencies at 2kHz (second harmonic), 3kHz (third harmonic), and so forth.

HDCP See “High-band width Digital Content Protection.”

HD DVD New optical disc format that can store 30BGB on a dual-layer disc the size of a DVD. Competing with Blu-ray Disc to be the high-definition replacement for DVD.

HDMI see “High-Definition Multimedia Interface”

HDTV (high-definition television) Refers generally to high-resolution television transmissions and displays, which must exhibit a vertical resolution of 720 or higher to qualify as HDTV.

hertz (Hz) The unit of frequency; the number of cycles per second. Kilohertz (kHz) is thousands of cycles per second.

HiFi Short for High Fidelity, the high-quality audio format used in some VHS videocassette recorders. A VHS HiFi VCR can provide excellent sound quality. Contrasted with VHS linear tracks, which offer poor sound quality.

High-bandwidth Digital Content Protection (HDCP) An encryption technique that allows transmission of digital video and digital audio between components in a home-theater system, but prohibits those signals from being recorded. Used with the DVI and HDMI interfaces.

High-Definition Multimedia Interface (HDMI) Digital interface that can carry HD video, high-resolution digital audio, and control information on a single cable.

high-definition television see “HDTV”

high-density layer The information layer in a Super Audio CD that contains high-resolution digital audio.

high-pass filter A circuit that allows high frequencies to pass, but blocks low frequencies. Also called a “low-cut filter.” High-pass filters are often found in A/V receivers and A/V controllers to keep bass out of the main speakers when using a subwoofer.

high-resolution digital audio Generally regarded as digital audio with a sampling rate greater than 48kHz and a word length longer than 16 bits.

home theater The combination of high-quality audio and video in your home.

Home THX A set of patents, technologies, and playback standards for reproducing film soundtracks in the home as the producer intended. THX doesn’t compete with surround formats such as Dolby Pro Logic or Dolby Digital, but instead builds on them.

horizontal resolution A number that specifies the amount of fine detail a video display can show (or a video format can contain) in each horizontal scanning line. In analog formats such as VHS videotape and CRT-based television sets, horizontal resolution is expressed in TV Lines (TVL). In digital formats and fixed-pixel display devices, horizontal resolution is expressed in the number of pixels per horizontal line of video. For example, VHS has a horizontal resolution of 240 TVL, DVD has a horizontal resolution of 720 pixels, and HDTV’s maximum horizontal resolution is 1920 pixels. Technically, horizontal resolution is specified as the number of pixels or TVL per picture height. This requirement prevents widescreen formats from having an apparently higher horizontal resolution than 4:3 formats.

Hz See “hertz.”