| 翻訳と辞書 |
S-VHS
(for Super VHS) is an improved version of the VHS standard for consumer-level analog recording videocassettes. JVC introduced the new standard in Japan in April 1987 with the HR-S7000 VCR, and in certain overseas markets soon afterward.
==Technical information==
Like VHS, the S-VHS format uses a "color under" modulation scheme. S-VHS improves luminance resolution by increasing luminance bandwidth. Increased bandwidth is possible because of increased luminance carrier from 3.4 MHz to 5.4 MHz.〔http://catalogs.infocommiq.com/AVCAT/images/documents/pdfs/TT189%20-%204611.pdf〕 Increased luminance bandwidth produces a 60% improvement in (luminance) picture detail, or a horizontal resolution of 420 vertical lines per picture height versus VHS's 240 lines. The often quoted horizontal resolution of "over 400" means S-VHS captures greater picture detail than even NTSC analog cable and broadcast TV, which is limited to about 330 TV lines (TVL). In practice, when time shifting TV programs on S-VHS equipment, the improvement over VHS is quite noticeable. Yet, the trained eye can easily spot the difference between live television and a S-VHS recording of it. This is because S-VHS does not improve other key aspects of the video signal, particularly the chroma signal. In VHS, the chroma carrier is both severely bandlimited and rather noisy, a limitation that S-VHS does not address. Poor color resolution was a deficiency shared by S-VHS's contemporaries (Hi8, ED-Beta), all of which were limited to 0.4 megahertz or 30 TVL resolution.
In terms of audio recording, S-VHS retains VHS's conventional linear (baseband) and Hi-Fi (AFM) soundtracks. Some professional S-VHS decks can record a PCM digital audio track (stereo 48 kHz), along with the normal video and Hi-Fi analog audio.
As an added bonus, due to the increased bandwidth of S-VHS, Teletext (PAL) signals can be recorded along with the normal video signal. As a result these are also played back (though not on standard VHS machines). A suitably Teletext equipped receiver (TV, PC card, etc.) displays the recorded Teletext information as if the video were being viewed live.
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「S-VHS」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|