Mini DV Tape FAQ's
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What is DV ?
DV (Digital Video) format is an worldwide standard created by Sony, Matsushita (Panasonic), JVC, Sharp, Thompson Multimedia and etc. And now, there are over 60 companies in the DV consortium.
DV, initially known as DVC (Digital Video Cassette), uses a 1/4 inch (6.35mm) metal evaporate tape to record very high quality digital video. The video is sampled at the same rate as D-1, D-5, or Digital Betacam video -- 720 pixels per scanline -- although the color information is sampled at half the D-1 rate: 4:1:1 in 525-line (NTSC), and 4:2:0 in 625-line (PAL) formats.
DV uses intraframe compression: Each compressed frame depends entirely on itself, and not on any data from preceding or following frames. DV also uses adaptive interfield compression; if the compressor detects little difference between the two interlaced fields of a frame, DV will compress them together, freeing up some of the "bit budget" to allow for higher overall quality.
DV video information is carried in a nominal 25 Mbps data stream. Once you add in audio, subcode (including timecode), Insert and Track Information (ITI), and error correction, the total data stream comes to about 29 Mbps or 3.6 Mbps.
Eventually, Mini DV, DVCAM, and DVCPRO format also know as DV format. All three utilize the same compression method called the DV-25 (which is sometimes just referred to as DV compression). The same data is recorded onto each format, with the difference between the formats being how the data is physically recorded onto the tape. Video compressed using DV-25 does not have to be recorded onto tape; while video files on a computer can be compressed into DV.
What's the difference between DV, DVCAM, and DVCPRO?
The DV formats tabulated table
What are the differences between Mini DV tape format and Digital8?
The Mini DV tape format is approximately 56% smaller than an 8mm technology that Digital 8 uses was developed a decade earlier, in 1984. The DV format is supported by over 56 companies worldwide, ensuring compatibility with other DV equipment, while Digital 8 is currently supported by only two companies (Sony & Hitachi).
Can you Mix brands/manufacturers of MiniDV/DV tape ?
Yes and No. According to Mr. Weideman you can the issues have been resolved, but this is not my practical experience. The issue seems to be the formulation of tape lubricants. When Sony and Panasonic manufactured tapes are mixed the lubricants intermingle and become tacky. The result is that the tape mechanism will stop. (On a Canon XL-1 this is shown in the viewfinder by "Eject Tape" flashing in the viewfinder.)
The best advice seems to be to stick with tapes from the same brand. This includes continuing use of Head cleaning tape from the same manufacturer. The problem is that it is not always practical or desirable to use any particular brand of tapes. This is complicated by OEM arrangements, where one manufacturer allows another to repackage tapes under their brand. These arrangements are jealously guarded secrets.
Generally speaking, Panasonic Digital Media manufactures about 70% of DV media, Sony manufactures 25% and TDK manufactures 5%. These figures are approximate and of course subject to change. I know Maxell and Fuji have DV and DVCPRO tape brands, I would expect these manufacturers to enter the game very soon if they are not already as both have a history of providing media.
What I can find from direct experience of these OEM arrangements is that Panasonic makes Canon and JVC tape. Sony makes its own tape. TDK makes its own. I do not know who makes Fuji, Maxell or other tape brands.
Can I use LP and SP on the same tape ?
Yes, with some cautions. If you are just re-recording over a tape recorded in LP with SP or vice versa in a single pass, then you have little to worry about. What you need to avoid is having a change in recording speed somewhere in the middle of your tape. Such a change will cause dropped frames and noise.
One way to help avoid this is to stripe, or record the black on the whole tape, with the tape speed you'd like to use next. Another good practice is to start recording a few seconds before what you want to capture. Either of these will likely do the trick, together they will assure a decent re-use of any tape in good condition.
What is the chip for on some DV tapes ? Do I need it ?
The chip found on some MiniDV and DV tapes is for recording extra data items, such as index marks and titles. Only a few cameras use this feature, mostly from Sony. I am presently looking into a list of models that support use of the chip.
I do not use the feature myself, I use clear legible handwritten tape labels and separate paper tape logs for every tape. The chip does not offer as much flexibility for comments. There are a number of applications for the Palm pilot and PC's that can handle the data better, including some logging applications that can actually create an edit decision list.
I do not recommend making this chip feature a priority in tape purchase or camera selection.
What is a dropout ?
A dropout is when your camera fails to record an image for a short period. The most common cause is the tape losing contact with the recording heads. This can be because of irregular tape shrinkage, poor tape tensioning (along the length of the tape most often, but sometimes across the height of the tape), excessive camera motion, poor tape storage practices or defects in the tape surface.
Most of the time dropouts look like an area of the screen that is black with random square or rectangular digital artifacts appearing all over the picture area. There is often a clicking or whistling sound, or a digital shirping that accompanies a visual dropout. It is possible to have either a video or audio dropout alone, but video dropouts are far more common.
How should DV tape be stored ?
Under ordinary ccumstances you can simply place the tapes on a shelf, much like a book, on its edge in its case with the spine label facing out. This is also the correct way to transport tapes, as it will minimize vibration. DO NOT store tapes near any magnetic fields. (i.e. Speakers, Electric motors, magnets, computer monitors, network hubs, audio or video cabling or anything else that can generate a magnetic field.) Short term exposure has few deleterious effects, but over time even a modest magnetic field can seriously degrade the tape.
When you store for an extended period you have to take more care. Panasonic Digital media recommends archival at 10-25° C at 40-60% Relative Humidity. Care should be taken to minimize temperature fluctuation over time and keep the storage area dust free. This will minimize expansion and contraction of the tapes base film.
If you are storing tape near an automatic fire extinguisher be certain that it uses a gaseous extinguishing agent. Liquid or powder extinguishers can potentially damage the tapes.
All tapes should be completely rewound before storage for any period of time. If you don't it can lead to uneven stretching of the tape. Tapes should be periodically (not less than every 3 years) fast forwarded and rewound completely. (You should do this for any tape you plan to re-record on that has been stored for any extended period of time.)
Basic Comparison of Two MiniDv and Digital8 Format
Features Common To Both Formats:
MiniDV, Digital8 Format Differences:
- Digital Video Recording, using the same compression/decompression standards.
- PCM audio recording (1.2bit/1.6bit).
- 500 line video resolution capability.
- 640x480 resolution still picture resolution.
- IEEE 1394 (Firewire, i-Link) computer interface.
- Uses HI8/8mm tape as the recording media (about $4 per tape).
- Uses the same body design and size as a HI8/8mm camcorder.
- D8 Format currently only manufactured by Sony.
- Both Digital and Analog Video In/Out capability (Analog In/Out not available in Europe).
- Maximum One Hour recording time on each tape (using a 120min HI8 Tape).
- Can also playback Analog 8mm/Hi8 tapes.
- Uses MiniDV (6mm) tape as the recording media (about $6 per tape).
- Maximum Ninety minutes record time on tape in LP mode (using a standard 60min tape length).
- Camcorders can be much smaller that Digital8 camcorders.
- MiniDV format manufactured by several companies, including Canon, JVC, Panasonic, Sharp, and Sony.
To summarize, MiniDV and Digital8 are both good options, but for different reasons:
The Digital8 Option
If you are current owner of a Hi8 or 8mm camcorder, upgrading to Digital8 might be the option for you. Digital8 is a hybrid system that not only allows digital video recording, but also provides for playback compatibility with older 8mm and Hi8 tapes. Also, with the same computer IEEE1.394 interface as MiniDV, Digital8 is also compatible with a multitude of Desktop Video. editing options.
Digital8 camcorders also have analog video in/out capability (except European models), which enables one to make a digital video copy from any analog video source that has an RCA or S-Video output. Although most MiniDV camcorders also have this ability, this feature is often eliminated on the more entry level models.
The MiniDV Option
If you are starting from "ground zero" and are not concerned about compatibility with previous formats or have price concerns, then MiniDV might be a better choice. The Camcorders are smaller, and have a host of features for excellent video making. The most important factor has to do more with politics than technology, however. MiniDV is an industry standard that not only has a five year track record, but is supported by several major manufacturer's including Canon, JVC, Panasonic, Sharp, and, ironically, Sony (which supports both MiniDV and Digital8). This allows not only an abundant selection of MiniDV models, from tiny units not much larger than a pack of cigarettes to the large semi-pro 3CCD types used in independ film production and news gathering, but also allows for more flexibility for video duplication. The pro versions of MiniDV, referred to as DVcam and DVCpro are standards that are used in many commercial and broadcast video applications around the world. Unless Sony picks up more partners in supporting Digital8, it will eventually fall by the wayside, especially if the cost of MiniDV camcorders continue their downward spiral (some MiniDV camcorders already cost less than some of the Sony D8 models).
Last, but not least, although there are a couple of portable Digital8 VCRs, but they are expensive. Ironically, Sony, along with Panasonic and JVC have both consumer and professional MiniDV VCRs available (both desktop and portable) and, although expensive ($1.,000 and up), they are still available for those that feel the need and have the cash.