Digital8
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Digital8 (or D8) is a consumer digital videotape format developed by Sony, and introduced in 1999.
The Digital8 format is a combination of the older Hi8 tape transport with the DV codec. Digital8 equipment uses the same videocassettes as analog Hi8 equipment, but differs in that the audio/video signal is encoded digitally (using the industry-standard DV codec.) Since Digital8 uses the DV codec, it has identical audio and video specifications.
To facilitate digital recording on existing Hi8 videocassettes, the tape media is moved linearly past the recording heads at higher speed, while the video head drum spins 2.5x faster. For both NTSC and PAL Digital8 equipment, a standard-length cassette will store 60 minutes (at Standard Play). Current Digital8 equipment can also record in Long Play (LP) mode, which increases recording time from 60 minutes to 90 minutes. A few vendors sell long-duration tapes, with an SP recording time of 90 minutes (or 135 minutes in LP.)
Digital8 (SP) recordings can be made on standard-grade Video8 cassettes, but this practice is discouraged. Hi8 metal-particle cassettes are the recommended type for Digital8 recording, and most tapes currently sold are marked for both Hi8 and Digital8 usage.
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[edit] MiniDV/DVC vs. Digital8
Contrary to popular perception, the Digital8 format is not technically inferior to miniDV -- both are identical at the bitstream level. From a user standpoint, Digital8 is DV (or rather, equivalent to and compatible with consumer miniDV.) At an application level (for example, in a 1394/Firewire link), a Digital8 camcorder appears and behaves exactly like a Mini DV camcorder.
Digital8 and Mini DV use different, non-interchangeable cassette media, with Digital8 cassettes being the physically larger of the two. The two formats may also use different media formulations: Digital8 can use metal-particle or metal-evaporated media, while miniDV is based solely on metal-evaporated media. The standard (SP) recording time for both formats, on standard length media, is 60 minutes. Special high capacity cassettes are also available for both formats which can extend these figures, and both offer Long Play modes which extend recording times by 50% (not 100% as for video8 Long Play).
In addition, Digital8 uses tape at 28.666mm per second; more like the higher-end DVCAM (28mm/s) and DVCPRO (34mm/s). MiniDV uses tape at 19mm/s. According to SONY's press release of January 7, 1999, for the MiniDV format one frame is recorded onto ten tracks, with the Digital8 format two tracks' worth of information is recorded vertically onto five tracks. The use of this recording method enables digital images to be recorded on a Hi8 tape.
[edit] Market segment
While analog Hi8 video enjoyed widespread use by amateur home video, current affairs TV programs, and some professional news organizations, Digital8 seems to remain strictly a consumer (amateur) product. This is likely a reflection of Sony's design and market objectives for Digital8 format: to serve as a low-cost upgrade path for current customers (from analog 8 mm), by leveraging existing manufacturing infrastructure of 8 mm video equipment. Furthermore, Digital8 was released some time after miniDV, giving the rival DV format a lead in the professional market. While little or no Digital8 equipment has been produced for the professional market, there are no technical barriers opposing its development. In fact, Digital8 cameras have been used on the professional side of the film/TV business; example, Hall of Mirrors, The Movie
In the early years after Digital8's introduction, Sony sold a product line with coverage from entry level to high-end consumer. The best of the consumer Digital8 product line was a small number of megapixel camcorders, sold during 2001-2003. The Sony DCR-TRV730/828/830 (and the later DCR-TRV740/840), were the only Digital8 camcorders to be built with a high-quality (1/4.7") "megapixel" Advanced HAD (Hole Accumulation Diode) CCD. All megapixel camcorders featured a CCD sensor with an active pixel-count of ~670K, ranking them competitive with similarly equipped single-CCD MiniDV camcorders.
But since that time, Sony has withdrawn this capability (as well as manual functions) from its Digital8 product line, preferring to promote high-density imagers in its MiniDV and DVD camcorders. Furthermore, the number of models in Sony's Digital8 product line has shrunk to just 1 model by mid 2006, raising questions about the format's future.
As of 2005, Digital8 product line caters purely to the entry-level consumer. This is most likely because the larger, bulkier Digital8 cassette is perceived as an inferior technology, even though the Digital8 and DV formats offer indistinguishable A/V performance. Sony, the format's original backer, is the only company still producing Digital8 equipment. Hitachi marketed a few Digital8 camcorders for a while but no longer does so.
[edit] Analog recordings
Digital8 equipment cannot record in analog Video8/Hi8 format, but some equipment offers playback compatibility with 8 mm analog recordings. Even so, there are limitations: audio playback is limited to the analog soundtrack -- if present, digital (PCM) sound is inaccessible. Most Digital8 camcorders with analog playback also simultaneously digitize the analog footage into the DV format, sending the converted material through the camcorder's FireWire interface. This facilitates easy, one-step uploading of analog 8 mm recordings to a Firewire-equipped computer. As Digital8 offers audio/video performance equal to DV, little if any of the original recording's fidelity is lost due to the conversion process (although some purists contend that high-end Hi8 playback equipment looped through a DV encoder produces better results.)
[edit] See also
- 8 mm film
- Super 8 mm film
- Video8
- Hi8
- Data 8
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| Magnetic tape |
VERA (1952) - 2 inch Quadruplex videotape (1956) - 1 inch type A videotape (1965) - U-matic (1969) - Video Cassette Recording (1972) - V-Cord (1974) - VX (aka "The Great Time Machine") (1974) - Betamax (1975) - 1 inch type B videotape (1976) - 1 inch type C videotape (1976) - VHS (1976) - Video 2000 (1979) - VHS-C (1982) - M (1982) - Betacam (1982) - Video8 (1985) - MII (1986) - D1 (1986) - S-VHS (1987) - D2 (1988) - Hi8 (1989) - D3 (1991) - D5 (1994) - Digital-S (D9) (199?) - S-VHS-C (1987) - W-VHS (1992) - DV (1995) - Betamax HDCAM (1997) - D-VHS (1998) - Digital8 (1999) - HDV (2003) |
| Optical discs |
Laserdisc (1978) - Laserfilm (1984) - CD Video - VCD (1993) - DVD (1996) - MiniDVD - CVD (1998) - SVCD (1998) - FMD (2000) - EVD (2003) - FVD (2005) - UMD (2005) - HD DVD (2006) - Blu-ray Disc (BD) (2006) - DMD (2006?) - AVCHD (2006) - Tapestry Media (2007)- HVD (TBA) - Protein-coated disc (TBA) - Two-Photon 3-D (TBA) |
| Grooved Videodiscs |
SelectaVision (1981) - VHD (1983) |
