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Introduction
Standard DVC (Digital Video Cassette) is a digital video cassette format that utilizes the DV encoding standard.
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Introduction
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Standard DVC (Digital Video Cassette) is a digital video cassette format that utilizes the DV encoding standard. According to the DV encoding standard, video must be recorded using 6.35 mm (1/4 inch) magnetic videotape. However, any size cassette can be used to house DV tape. Originally, DV cassettes were available in two sizes: Standard DVC and MiniDV. Most DV camcorders available on the consumer market were compatible with either Standard DVC or MiniDV cassettes. Some professional equipment, such as the JVC Professional DV camcorder, could accommodate both cassette sizes. DVC cassettes are larger and can record more video than MiniDV cassettes (3.5 - 4 hours of compared to 60 minutes), however MiniDV cassettes quickly became more popular among consumers due to their small size and portability.
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Physical Characteristics
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| Tape width | ¼ inch (6.35mm) |
|---|---|
| Tape composition | Metal evaporate (ME) |
| Cassette dimensions | 97.5 × 64.5 × 14.6 mm |
| Identifying features | Cassettes labeled with DV or DVC |
| Common manufacturers/brands | Sony, Panasonic, JVC |
| Playback |
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Technical Characteristics
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| Record time | Standard play: 3 hrs Long play: 4.6 hrs |
|---|---|
| Track pitch | Standard play: 10 microns Long play: 6.7 microns |
| Track width | Standard play: 10 microns Long play: 6.7 microns |
| Record/playback speed | Standard play mode: 18.81 mm/sec |
| Bitrate | 25 Mbit/s |
| Bit depth | 8 bit |
| Colour sampling | PAL: 4:2:0 NTSC: 4:1:1 |
| Resolution | PAL: 720x576 |
| Compression | 5:1 DVC-format DCT compression (intra-frame) |
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| Binder deterioration | |
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| Description | Commonly known as "sticky shed syndrome." Affected records will have a visible gummy or powdery residue on the surface of the tape. This can damage both the recorded material and playback equipment. Back-coated tapes are most affected by this type of deterioration. |
| Cause | Polyester urethane is prone to moisture absorption which can cause the molecular structure of the binder to break down. This process is accelerated by high temperature and high humidity. |
| Remedy | Environmental conditioning: Moving the tape to a controlled storage environment (40°C / 20 to 25% Relative Humidity) may reverse the affects of hydrolysis over time. Baking: Holding the tape at an elevated temperature (45°C to 55°C) for a brief period of time (up to 36 hours) can temporarily remove moisture and allow normal playback for a period of one to two weeks. Tapes should not be rewound before baking. |
| Drop-out | |
| Description | A brief signal loss caused by a tape head clog, missing magnetic oxide particles, tape defect, or debris on the tape or machine. These factors can reduce head-to-tape spacing and result in the appearance of white spots or streaks on playback. Multiple drop-outs per frame will result in a snowy appearance. |
| Cause | Tapes kept in dusty conditions will accumulate particulate matter, increasing the risk of drop-out. |
| Remedy | Flaking/missing magnetic oxide particles are an indication of tape deterioration. This type of drop-out cannot be corrected physically. |
| Mould | |
| Description | Active mould is generally moist while dormant mould is dry and dusty. Mould growths may be white, black, brown or mustard-coloured and usually have a pattered, fuzzy, or thread-like appearance. Mould can cause permanent damage to tapes over time if not removed. Fungus and mould is also a significant health hazard and affected materials should be handled using gloves and masks. |
| Cause | Storing tapes at high temperature and relative humidity levels can facilitate the growth of mould. |
| Remedy | Mouldy tapes should be isolated from unaffected materials to prevent cross contamination. Store tapes at a temperature of 24°C in an environment with effective air circulation and less than 50% Relative Humidity. Loose mold can be vacuumed from the tape pack and then the tape should be treated with an appropriate fungicide. |
| Stretching and breaking | |
| Description | The elongation of parts of the tape, across the full width of the tape or -most likely- on one or the other side of the tape The separation of tape into two or more pieces. |
| Cause | usually results from either improper wind or from faulty equipment. May cause long-edge or curvature problems, and distort the signal, but the data can generally be retrieved from an analog tape, usually with a decrease in signal quality." Improper handling or use of playback equipment. | Remedy |
| Accidental recording | |
| Description | Camera operators can accidentally record over pre-existing footage |
| Cause | Tape is set to "record mode" when it is inserted into camera or deck |
| Remedy | Ensure tape is set to "safe mode" before inserting into camera or deck |
Further Reading
Visit the /wiki/spaces/ALC/overview for further reading on /wiki/spaces/ALC/pages/1891631115.
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| . Mould can cause permanent damage to tapes over time if not removed. Fungus and mould is also a significant health hazard and affected materials should be handled using gloves and masks. | |
| Cause | Storing tapes at high temperature and relative humidity levels can facilitate the growth of mould. |
| Remedy | Mouldy tapes should be isolated from unaffected materials to prevent cross contamination. Store tapes at a temperature of 24°C in an environment with effective air circulation and less than 50% Relative Humidity. Loose mold can be vacuumed from the tape pack and then the tape should be treated with an appropriate fungicide. |
| Stretching and breaking | |
| Description | The elongation of parts of the tape, across the full width of the tape or -most likely- on one or the other side of the tape The separation of tape into two or more pieces. |
| Cause | usually results from either improper wind or from faulty equipment. May cause long-edge or curvature problems, and distort the signal, but the data can generally be retrieved from an analog tape, usually with a decrease in signal quality." Improper handling or use of playback equipment. |
| Remedy | |
| Accidental recording | |
| Description | Camera operators can accidentally record over pre-existing footage |
| Cause | Tape is set to "record mode" when it is inserted into camera or deck |
| Remedy | Ensure tape is set to "safe mode" before inserting into camera or deck |
Further Reading
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Visit the /wiki/spaces/ALC/overview for further reading on /wiki/spaces/ALC/pages/1891631115.
References
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AMIA. "Video Preservation Factsheets." Accessed December 10, 2020.
Bensinger, Charles. "Chapter 6: All about videotape." In The Video Guide, Second Edition, 71-75. Santa Barbara, California: Video-Info Publications, 1981.
Bogart, John Van. "What Can Go Wrong With Magnetic Media?" In Magnetic Tape Storage and Handling: A Guide for Libraries and Archives. Washington, DC: The Commission on Preservation and Access, 1995.
Casey, Mike. "FACET: Format characteristics and preservation problems." Bloomington, IN: Indiana University, 2007.
Gibson, Gerald. D. "Magnetic tape deterioration: recognition, recovery and prevention." Paper presented at the IASA Conference, Perugia, August 26, 1996.
Jones, Gerald Everett and Pete Shaner. "DV Technology and the Camcorder." In Real World Digital Video. Second Edition. Peachpit Press, 2005.
JVC Victor Company of Japan Limited. "Professional DV." Accessed February 2, 2021.
MediaCollege.com. "DV video." Accessed February 2, 2021.
Nielsen, Rebecca. "Media Recognition: DV Part 2." Bodleian Libraries. March 26, 2012.
Wheeler, Jim. "Videotape preservation handbook." 2002.
Wilt, Adam J. "The DV, DVCAM & DVCPRO Formats: The DV formats tabulated." August 28, 2005.
Wilt, Adam J. "The DV, DVCAM & DVCPRO Formats." July 16, 2006.