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The first attempt at producing pre-recorded HDTV media was a scarce Japanese analog MUSE-encoded laser disc which is no longer produced. See MUSE-LD. In the U.S. market, the first currently available prerecorded HD media was D-Theater. Comprising less than 100 titles and utilizing a 28-Mbit/s MPEG2 stream at 720p or 1080i with either Dolby Digital 5.1 or DTS encoding, D-Theater is an encrypted D-VHS format, and only D-Theater-capable D-VHS players can play back these tapes. This format is superior to broadcast HDTV due to its higher bandwidth and, of course, the ability to do non-realtime optimization of the encoding, which is not possible with broadcast HDTV. D-Theater is currently a small niche market even within the niche HDTV community, and it appears as if the final D-Theater title was published in 2005 with 20th Century Fox release of i,Robot. In 2006, the first pre-recorded digital optical HDTV media were introduced. There were two competing standards, Blu-ray Disc and HD DVD. The first HD DVD players and discs were released on April 18, 2006 in the United States. Blu-ray Disc was released on June 20, 2006. == HD DVD and Blu-ray == (詳細はDVD Forum and the Blu-ray Disc Association failed to agree on standards for high-definition 12-cm discs, a format war was under way between the DVD Forum's HD DVD (formerly "Advanced Optical Disc") standard and the Blu-ray Disc Association's Blu-ray Disc standard. Although there was disagreement about physical format technology, both the HD DVD and Blu-ray factions selected the same three video codecs to be mandatory in their designs: specifically, MPEG-2 Part 2, VC-1, and H.264/AVC. They were engaged in a format war up until February 2008, to determine which of the two formats will become the leading carrier for high-definition content to consumers. This situation was similar to the VHS/Betamax format war in consumer video recorders in the late 1980s. The manufacturers of HD DVD, Toshiba, announced in February 2008 that they were ceasing production of their HD DVD players indefinitely, citing low demand for HD DVD and the growing use of Blu-ray, which had become popular due to its inclusion as part of the PlayStation 3 among other things. There are now some DVD players that will output enhanced or high-definition signals from standard-definition DVDs. This upconversion process can improve the perceived picture quality of standard-definition video. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「High-definition pre-recorded media and compression」の詳細全文を読む スポンサード リンク
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