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Ask most folks in the video industry what a D-VHS VCR is, and you will probably get a puzzled look. Most likely, they will guess it is a VHS deck with a FireWire port.
Ask a home-theater aficionado about D-VHS, and you'll get a far more knowledgeable answer. Whether they own a deck or not, D-VHS is well known. It allows those with HDTV sets to buy pre-recorded D-Theater movies in the 1080i format with Dolby Digital 5.1 soundtracks. D-VHS also enables those with IEEE 1394-equipped HD set-top boxes to record clones of both SD and HD broadcasts and DBS programming.
It's the ability of D-VHS to handle HD material that makes it a valuable tool for the video industry. JVC positions it as the ideal way to distribute super high-quality digital dailies. But democratizing the demand for HD distribution is the JVC JY-HD10 single-chip HD camcorder, a new prosumer-level tool for creating content in HDV, the MPEG-2-based HD format launched by JVC and Sony.
OK. That's why some of us know and like D-VHS. But what exactly is it? The primary ingredient is a VHS transport - a transport for which JVC owns the patent. This transport is both highly evolved and very cheap to produce. Add to this base all the usual electronics that go with any VHS deck.
D-VHS becomes a very affordable way of distributing HDV and other kinds of HD productions with the recent release of the JVC SR-VD400US, a D-VHS VCR with a street price way under $1,000.
Adding the "D" to VHS
What adds the "D" to VHS is the inclusion of a high-definition MPEG-2 decoder with analog component (YPbPr) output. Digital operation is also supported by a standard-definition MPEG-2 encoder. It can encode from three sources: the internal NTSC tuner, composite and S-Video inputs, and digital data from an internal DV codec. This DV codec allows you to connect almost any DV25 source to the deck and record the input as MPEG-2.
The SR-VD400US is able to encode MPEG-2 at 28.2Mbps (HS mode), 14.1Mbps (STD mode), 4.7Mbps (LS3 mode), and 2.8Mbps (LS5 mode). The HS data rate is achieved by writing (and reading) data using two heads simultaneously, a trick JVC invented for its D-9 (Digital-S)...