Introduction
DVCAM is a professional-quality variation of the DV video encoding that was introduced by Sony in 1996. DVCAM also refers to video tape recorders and DV and MiniDV videocassettes that are designed to support the DVCAM video recording specification. DVCAM uses the same tape width and compression scheme as DV but increases the track pitch from 10 microns to 15 microns. The recording speed of DVCAM is also significantly higher than DV cassettes. DVCAM recordings have improved colour rendition and robustness, employ “locked audio” tracks, and are well suited for linear editing environments. The DVCAM format was primarily used in professional markets for electronic news gathering, cable television, documentaries and other long form video production.
Physical Characteristics
| Tape width | ¼ inch (6.35mm) |
|---|---|
| Tape composition | Metal evaporate (ME) |
| Cassette dimensions | Large cassettes: 4 7/8" x 3" x 9/16" Small cassettes: 2 9/16" x 1 7/8" x 9/16" |
| Container dimensions | Large cassettes: 5 3/8" x 3 11/16" x 3/4" Small cassettes: 3 1/16" x 2 1/2" x 3/4" |
| Identifying features | Cassettes are usually bluish grey and are labeled as DVCAM in the upper righthand corner |
| Common manufacturers/brands | Sony |
| Playback | DVCAM tapes can be played using DVCAM, DV and DVCPRO VTRs DVCAM VTRs can playback DVCAM and DV tapes. |
Technical Characteristics
| Record time | Large cassettes: 184 minutes Small cassettes: 40 minutes |
|---|---|
| Track pitch | 15 microns |
| Track width | 15 microns |
| Record/playback speed | 28.215 mm/sec |
| Bitrate | 25 Mbit/s |
| Bit depth | 8 bit |
| Colour sampling | NTSC: 4:1:1 PAL: 4:2:0 |
| Resolution | NTSC: 720x480 PAL: 720x576 |
| Compression | 5:1 DVC-format DCT compression |
Technical standards
- Society for Motion Picture Technical Engineers (SMPTE) standard for television 314M Data structure for DV-based audio, data and compressed video – 25 and 50 MB/s. The differences between IEC 61834-5 and SMPTE 314M are shown in Annex A of SMPTE 314M.
Storage
| Storage environment: temperature | Ideal: 40–54°F (4.5–12°C) Acceptable: 55–60°F (13–15.5°C) |
|---|---|
| Storage environment: humidity | 30–50% RH |
| Container | DVCPRO containers should pass the Photographic Activity Test (PAT) as specified ISO Standard 18916:2007
Containers are acceptable if they:
Unacceptable containers must be replaced with clean, inert containers. |
| Orientation of tape in storage | Vertical on its end (like books) |
Risk assessment
Digital video material stored on magnetic videotape is considered to be at high-risk of loss or degradation.
Polyester base film used in videotape is considered very stable.
Other components of the videotape, including the binder, are considerably less stable and are more likely to be the cause of degradation.
Format obsolesce, including lack of well-functioning playback equipment poses an equal or even greater risk than degradation, even with higher quality formats such as Digital Betacam
Digital video material stored on magnetic tape should be appraised or re-appraised to determine the nature and signficance of video elements contained on the tape and whether the video elements have sufficient archival value to justify reformatting and long-term preservation as digital video files.
Types of damage and deterioration
| Binder deterioration | |
|---|---|
| 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.
References
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.
Jimenez, Mona and Liss Platt. "Videotape Identification and Assessment Guide." Texas Commission on the Arts. 2004.
MediaCollege.com. "The DVCAM Format." Accessed February 3, 2021.
Museum of Obsolete Media. "DVCAM (1996 – )." Accessed February 3, 2021.
PCMag. "DVCAM." Accessed February 3, 2021.
Preservation Self Assessment Program. "Videotape: DVCAM." University of Illinois at Urbana-Champaign. Accessed February 3, 2021.
WDVA. "Do DV Formats Mystify You?" 2004.
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.