Цифрлық VHS: Жоғары сапалы бейнежазбаны сақтау форматы

Magnetic tape based format meant for the distribution of digital HD movies

D VHS is a digital video recording format developed by JVC, in collaboration with Hitachi, Matsushita, and Philips. The "D" in D VHS originally stood for "Data", but JVC renamed the format as "Digital VHS". Released in December 1997, it uses the same physical cassette format and recording mechanism as S VHS, but requires 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. It used MPEG 2 encoding and was standarized as IEC 60774 5.

As a final effort for VHS, the D VHS system had significant advantages 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 failed to make any headway into the video market. 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 are no longer 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 in the US. Cable, satellite companies, TiVo, and PCs equipped with cable card tuners all offered high definition digital video recorders, but archival has proven to be an obstacle, as proprietary boxes have restrictions on moving encrypted content. Outside of D VHS, only HD capture devices that use an analog conversion process, such as the Hauppauge HD PVR, have enabled removal of encrypted content off many of the above proprietary boxes. This uses an analog conversion process, producing slightly degraded but still high definition grade recordings. D VHS, on the other hand, does not need to take advantage of this so called "analog hole", since D VHS makes a pure bit for bit recording with no conversion necessary. This is made possible by compliance with CCI flag values carried by the digital streams, wherein only D VHS is allowed to digitally move recordings of content originally flagged as Copy Once off of a DVR device and onto a D VHS tape. This programming that complies with the CCI flags then marks such material on the tape such that no second generation copies can be made from the tape itself, though additional copies can still be made directly from the original DVR unit to additional tapes. Monthly rental fees to cable, TiVo, and satellite were also less with D VHS. The only PAL D VHS model sold in Europe was the JVC HM DR10000, also sold as the Philips VR 20D, and was standard definition only. This model 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 (the US 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 video outputs.

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 were available to the world market and sales of this format have been weak; correspondingly, prices remained high for both VCRs and media, contributing to low demand. Additionally, low consumer knowledge of D VHS's advantages and capabilities as well as input limitations led to its eventual demise. The introduction in 2006 of Blu ray and HD DVD rendered the format abandoned.

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. Sony's MicroMV format uses the same codec as D VHS. Therefore, D VHS capture software can also be used to transfer MicroMV tapes.