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Digital 8
Digital8 (or D8) is a consumer digital videotape format developed by Sony, and introduced in 1999. more...
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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.
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.
Read more at Wikipedia.org
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