D-VHS


D-VHS
D-VHS
D-VHS.svg
Media type Magnetic tape
Read mechanism Helical scan
Write mechanism Helical scan
Developed by Hitachi, Ltd., JVC, Panasonic Corporation
Usage Home movies, Television production

D-VHS is a digital recording format developed by JVC, in collaboration with Hitachi, Matsushita, and Philips. The "D" in D-VHS originally stood for Data VHS, but with the expansion of the format from standard definition to high definition capability, JVC renamed it Digital VHS and uses that designation on its website. It uses the same physical cassette format and recording mechanism as S-VHS (but needs higher quality and more expensive tapes), and is capable of recording and displaying both standard definition and high definition content. The content data format is in MPEG transport stream, the same data format used for most digital television applications. The format was introduced in 1998.

As a final effort for VHS, the D-VHS system is seen by its fans as a highly versatile domestic recorder (the other tape-based formats are DV and Digital8, which never gained any traction except as camcorder media), but given the wholesale move to DVD and then hard disk drive (HDD) recording, the format has failed to make any headway into the video market.

There has been no small-format version of D-VHS equivalent to VHS-C; JVC, the originator of the format, chose to use MiniDV for its digital camcorder lines, and since 2005 has also expanded into tapeless camcorder designs based on hard drive storage (the Everio line). JVC does market the Digital-S format for professional use; while the tapes and technology used are superficially similar to D-VHS tapes, the underlying data format is based on the DV codec and the media formulation is drastically different.

Contents

Tape Length and Speeds

D-VHS VCRs come with multiple speeds. "HS" is "High Speed", "STD" is "Standard" and "LS" is "Low Speed"; where LS3 and LS5 represent 3 and 5 times the standard length of tape. High-definition content such as 1920x1080 or 1280x720 is typically stored at 28.2 Mbit/s (HS speed). Standard-definition content such as 720x480 can be stored at bit rates from 14.1 Mbit/s down to 2.8 Mbit/s (STD, LS3, LS5 speeds).

The quality of STD speed is actually superior to the average DVD, since this speed has a much higher bitrate (approximately 14 versus 5 Mbit/s average) and suffers few compression artifacts. The LS3 speed is roughly equal to an amateur DVD with some visible artifacts in high-action scenes (4.7 Mbit/s), and LS5 appears similar to a medium-quality video download (2.8 Mbit/s). JVC's 40000 VCR was the only unit to support LS5 recording.

As a result of all these different speeds, the tape labels are a bit confusing for the consumer. D-VHS was originally a standard definition format that recorded at the STD speed. When High Definition recording and HS speed was later introduced, it required twice the amount of tape. For this reason, a DF-240 will record 240 minutes of standard definition, and 240/2 = 120 minutes of high definition. When reviewing the table, note that the digital speeds HS and STD are equivalent to the older analog speeds SP and LP.

Common D-VHS Tape Lengths
Tape Label Data storage Tape Length Rec. Time
HS or VHS-SP STD or VHS-LP LS3 LS5
DF-240 25 GB 248 m (813 ft) 120 min (2 h) 240 min (4 h) 720 min (12h) 1200 min (20 h)
DF-300 31.7 GB 314.464 m (1,048 ft) 150 min (2:30 h) 300 min (5 h) 900 min (15 h) 1500 min (25 h)
DF-420 44 GB 433 m (1,420 ft) 210 min (3:30 h) 420 min (7 h) 1,260 min (21 h) 2100 min (35 h)
DF-480 50 GB 500 m (1,640 ft) 240 min (4 h) 480 min (8 h) 1,440 min (24 h) 2400 min (40 h)

Issues/Advantages

There are technical issues with compatibility between recordings from Mitsubishi and JVC D-VHS decks. PAL and NTSC recordings are also incompatible. Very few models are available to the world market and sales of this format have been weak; correspondingly, prices have remained high for both VCRs and media, contributing to low demand. Also hurting demand, say D-VHS advocates, is poor marketing, resulting in low consumer knowledge of D-VHS's advantages and capabilities. Another primary roadblock to expansion, is the D-VHS's input limitations. The FireWire input is the only way to record high definition content to tape from an owner's TV, but very few TVs have FireWire connections (no current models), and cable boxes with FireWire have to be specially requested from cable companies. Satellite FireWire-equipped boxes are rare or nonexistent.

Existing tape media is bulky and more expensive than hard drives. Although cable companies are gradually switching to the H.264 codec, this should not be an issue for D-VHS units since they can act purely as data stores (like a hard drive but using tape instead), and thereby pass the previously-recorded H.264 data directly to the Set-top Box or TV (via i.Link/FireWire). Another alternative is a lengthy transfer to a computer for viewing. Finally, since machines will soon no longer be manufactured, maintenance of current recorders may prove difficult.

D-VHS's primary advantage is that it is still the best way to archive encrypted high definition material from cable programming. Cable, satellite companies, TiVo, and PCs equipped with cable card tuners all offer high-definition digital video recorders, but archival has proven to be an obstacle because proprietary boxes have restrictions on moving encrypted content, though HD capture devices from Hauppauge (HD PVR) and Elgato (EyeTV HD) have enabled removal of encrypted content off many of the above proprietary boxes. The HD DVR's analog conversion is slightly degraded but still high definition grade, and much better than standard definition. D-VHS does not need to take advantage of the so called "analog hole" that allows encrypted content to be recorded since D-VHS is a pure bit-for-bit recording with no conversion necessary, and therefore higher quality. Monthly rental fees to cable, TiVo, and satellite are less with D-VHS.

The JVC D-VHS deck released in the UK, was not a bitstream recorder, although it did have a FireWire input. Instead it is best thought of as a digital recorder for traditional analog inputs such as domestic analog TV and digiboxes for digital broadcasts. The deck was able to record D-VHS signals onto S-VHS tapes, which made it a cost-effective source of high quality domestic recordings (USA version also allows use of cheaper S-VHS media). Pictures were noticeably superior to S-VHS and were essentially transparent when compared to an off-air source. Using the LS3 mode, approximately 17.25 hours of digital video could be stored on a S-VHS E-240. The deck's biggest shortcomings were the lack of a DV output and, perhaps more crucially, the lack of RGB input via the SCART connector. NTSC versions had component outputs.

D-Theater

D-Theater logo.

In 2002, prerecorded D-VHS cassettes were sold under the brand name D-Theater in the US. While D-Theater is a D-VHS tape, it is incompatible with D-VHS decks without the D-Theater logo. They provide content in both 720p and 1080i as well as at least one Dolby Digital audio track. Supported films studios include 20th Century Fox, Artisan Entertainment, DreamWorks, and Universal Pictures. D-Theater provides much better audio and video quality than previous formats (VHS and DVD), but has since been displaced by the newer Blu-ray Disc format. D-Theater does have region code restrictions. There are 2 known regions; 1 for the USA, 2 for Japan. There has never been a D-Theater video release in region 2. Region code hacks for Japanese decks have been performed to support playback of US titles. The last film available was 20th Century Fox's I, Robot. This title was a surprise to many as there were no prior announcements nor any indication that the title was available. It was originally available only on JVC's D-VHS store in late 2004 and no other distributor had it (not even Fox itself). A couple of weeks later they started trickling out to more distributors after much delay and confusion about its existence. Alien vs. Predator was announced to retailers as also being released on the same day as I, Robot, but Fox later announced that Alien vs. Predator in fact was never shipped to any retail outlet; the copies that were produced have never seen the light of day, and the cause of this has never been explained by Fox.

Most tapes have built-in copy protection mechanism (DTCP, also known as "5c") (copy never) that disables copying via FireWire. HDNet productions and 2929 Entertainment via Magnolia Entertainment did provide some of their original content on D-VHS but without copy protection. Many of the tapes have an introduction by the owner Mark Cuban encouraging the viewer to make copies of the program in order to help distribute them.

DTS

Additional tracks may be included on D-Theater in other sound formats such as DTS. However, only the newest D-VHS players like JVC HM-DH40000, HM-DH5U, HM-DT100U, and Marantz MV-8300 include alternate audio track capabilities.

DTS D-Theater D-VHS tapes. * means DTS was not mentioned on the package.

20th Century Fox
20th Century Fox (continued)
Universal Studios


Dreamworks




Rare D-Theater tapes

When Lions Gate bought Artisan, a number of titles that were supposed to be released were cancelled. Some of them were Dirty Dancing, Basic Instinct, and Total Recall. 20th Century Fox, while experimenting with DTS, did test tapes of Phone Booth with DTS. There are also a number of Universal Studio test tapes without DTS tracks, but the released versions contain DTS without that fact being mentioned on the packaging. These DTS tracks were probably late additions. All of these examples of preproduction/review/test tapes have been in the hands of various D-Theater collectors.

See also

External links


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