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



HD-DVD
HD-DVD (HD stands for both high-density and high-definition) was under development before DVD came out. It finally emerged in 2003. Some high-definition versions of HD-DVD use the original DVD physical format but depend on new video encoding technology such as H.264 to fit high-definition video in the space that used to hold only standard-definition video. High-density formats use blue or violet lasers to read smaller pits, increasing data capacity to around 15 to 30 GB per layer. High-density formats use high-definition MPEG-2 video (for compatibility with ATSC and DVB HD broadcasts) and may also use advanced encoding formats, probably supporting 1080p24 video. HD discs will not play on existing players.
As of early 2003 there are five proposals for HD-DVD, with the possibility of others:
HD-DVD-9, aka HD-9
Advanced Optical Disc (AOD)
Blu-ray Disc (BD)
Blue-HD-DVD-1
Blue-HD-DVD-2



HDMI
HDMI (High-Definition Multimedia Interface) is the first industry-supported, uncompressed, all-digital audio/video interface. HDMI provides an interface between any audio/video source, such as a set-top box, DVD player, and A/V receiver and an audio and/or video monitor, such as a digital television (DTV).
HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It transmits all ATSC HDTV standards and supports 8-channel digital audio, with bandwidth to spare to accommodate future enhancements and requirements.



HDTV
High Definition TV is high-resolution digital television combined with Dolby Digital surround sound (AC-3). HDTV is the highest DTV resolution in the new set of standards. This combination creates a stunning image with stunning sound. HDTV requires new production and transmission equipment at the HDTV stations, as well as new television equipment for reception by the consumer. The higher resolution picture is the main selling point for HDTV. Imagine 720 or 1080 lines of resolution compared to the 525 lines people are used to in the United States (or the 625 lines in Europe) -- it's a huge difference!
Of the 18 DTV formats, six are HDTV formats, five of which are based on progressive scanning and one on interlaced scanning. Of the remaining formats, eight are SDTV (four wide-screen formats with 16:9 aspect ratios, and four conventional formats with 4:3 aspect ratios), and the remaining four are video graphics array (VGA) formats. Stations are free to choose which formats to broadcast.
The formats used in HDTV are:
720p - 1280x720 pixels progressive
1080i - 1920x1080 pixels interlaced
1080p - 1920x1080 pixels progressive



HTPC
Home Theater Personal Computer, a computer designed to be used as a media center for digital home entertainment such as Movies, Music, Television, Games.

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