DV Tape FAQ

Digital Video Tape Frequently Asked Questions

This FAQ got started in the year 2000 because I was constantly answering questions about DV Tape. I don't know why, but figuring out the answers for people is what made me an "expert." A lot of this material is based on my experience. A lot more is based on conversations and email exchanges I've had with Kenny Weideman, a consultant to Panasonic Digital Media and a former executive there.

A lot of this can be applied to VHS, SVHS, 8mm, Beta and other tape stocks. Just bear in mind I wrote it thinking about Metal Evaporated DV tapes.

Of course all the mistakes are mine. If you tell me about any mistakes and I can verify them I'll fix it.

3/20/2000- Alexander Ibrahim


UPDATED 2/6/2006

Questions

  1. My camera stopped recording and my viewfinder/LCD says "EJECT TAPE"
  2. What is a dropout ?
  3. Can you Mix brands/manufacturers of MiniDV/DV tape ?
  4. Can I use LP and SP on the same tape ?
  5. What is striping ? Should I do it ?
  6. How should DV tape be stored ?
  7. How often should I clean my DV VTR heads ?
  8. Is there a big difference in DV tape ?
  9. What are SP/LP modes ? Do they change the quality of my recordings ?
  10. What is the chip for on some DV tapes ? Do I need it ?
  11. What is the difference between Digital8 and MiniDV ?
  12. How do DV, DVCAM and DVCPRO compare ?

  1. My camera stopped recording and my viewfinder/LCD says "EJECT TAPE"

    Your camera's tape drive has gotten a bit stuck. Most often if you simply eject the tape, and place it back in the mechanism it will work fine, at least for a while.

    Camera's do not have very powerful engines relative to desktop recorders, sometimes they just get stuck. Most of the time this is not a real problem at all. If it only happens once in a blue moon, you should not worry too much about it.

    So how can you avoid it ? One way around it is to take new tapes and fast forward, then rewind them completely before attempting to record on them. I do this in my desktop recorder routinely. This "loosens up" the tape just a bit, and I have never had a tape stick during recording if I did this.

    So, why does it happen ? I only have a hypothesis: Most of the time this is the tapes fault...it has gotten a bit stuck to itself. That is why running it through forwards and backwards seems to work so well. It is mechanically unsticking the tape to/from itself.

    Another common reason is that the tape is improperly tensioned. Usually it is simply wound too tightly. Fast forwarding and rewinding in your camera or tape deck will usually retension the tape.

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  2. 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.

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  3. 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.

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  4. 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.

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  5. What is striping ? Should I do it ?

    Striping is the recording an entire tape end to end with a "dummy" signal. The reason you do this is to create continuous timecode on your tapes. DV is very sensitive to timecode, especially NLE capture applications. Usually it is recommended that you stripe with either black or camera bars. This gives you a visual cue if your tape is discontinuous.

    Generally, I recommend against striping. Most often it just causes unnecessary wear on your heads. However, if you plan on recording with lots of stops and starts with review of your video, it is worthwhile. This is primarily a precaution against the possibility of creating discontinuous timecode. In reality most camera's handle timecode rather well and will use timecode that is already on tape. If you are careful and rewind into material you do not need after reviewing you will be fine. Equally, you will be fine if you simply do not review your footage in the field.

    If you do not have time for these cautions then by all means do stripe your tapes beforehand. I like to keep a couple of striped tapes on hand at all times for any unexpected situations. You never know what you'll encounter, especially if you are doing ENG work. Most often I simply use whatever virgin or low use stock I have around. (Virgin stock is brand new manufacturer sealed tape.)

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  6. 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.)

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  7. How often should I clean my DV VTR heads ?

    Technically this is recorder maintenance, but tape can in fact be irreparably damaged by dirty or faulty tape transport mechanism. According to Panasonic Digital Media, you should clean your tape heads regularly with a quality head cleaning tape. This should be done EVERY 50 HOURS OF RECORDING OR PLAYBACK. If you have a dusty operating environment or one with humidity or temperature issues this should be done as often as every 25 hours. This is particularly important for VTR's which operate in smoky or dusty environments.

    Sony says that you should clean your tape heads with a cleaner ONLY WHEN THERE IS A VISIBLE PICTURE PROBLEM

    I think the truth is likely in between. For example, I have a JVC SR-VS10U which often is used for small to medium DV to VHS dub batches. I clean both transports between these jobs.

    Follow the manual instructions for your VTR first and foremost if they differ from the instructions for your head cleaning tape. Make sure your brand of head cleaning tape is manufactured by the same company that makes the tapes you use everyday. (You do use the same brand of tapes all the time right?)

    For convenience I have copied the instructions for: Sony DVM12CLD MiniDV Head Cleaner

    USAGE METHOD
    1. Insert the cleaning cassette into MiniDV video cassette recorder.
    2. Press the PLAY button or the START button. After running the tape for 10 seconds, press the stop button.
    3. Remove the cassette cleaner without rewinding it. Check that the video heads have been cleaned properly by recording and playing back a normal MiniDV cassette.
    If the video quality has not returned to normal, repeat steps 1 and 3.
    •Do not use the cleaning cassette more than 5 times consecutively.

    PRECAUTION

    1. Do not rewind the cleaning cassette after each use. Rewind the tape completely, only after it has reached the end. The entire tape can be used twice before replacing with a new cleaning tape.
    2. Do not use this cassette for recording.
    3. If there is no effect even when you clean 4 times in a row, the problem may be something else, Please consult the store where you purchased your DV unit.

    And instructions for: Panasonic AY-DVMCLA Professional DV Cleaning Cassette

    The Panasonic AY-DVMCLA is a high performance cleaning cassette tape designed to clean heads in just 10 seconds.
    Instructions:CAUTION - to avoid misuse and possible video head damage please read carefully. Do not use cleaning tape more often than necessary. Frequent use may cause head damage. This tape can not be used for recording and playback.
    For cleaning only.
    Prior to use, play another video tape to see that the problem dose not lie in the tape.
    Also, make sure tracking control is properly adjusted.
    1. Play the cleaning tape for 10 seconds only. Check result by playing a prerecorded tape.
    2. If picture is still unclear, try again. DO NOT USE MORE THAN 4 CONSECUTIVE TIMES.
    3. Do not rewind the tape after each use. When it reaches the end, rewind it to the beginning before using it again. The tape can only be used 2 times from beginning to end.
    4. If video noise dose not clear up after use, service may be necessary.
    5. Be sure to keep the cassette tape in the cassette case when not using it.

    Additional advice from the Panasonic Digital Media Group: Make sure and leave a brief 10 second cool down period between use of the head cleaners. In practice eject and cassette loading take longer than this so it would be hard to break that rule, but there it is.

    It is critical that you follow the maintenance schedule set out by your manufacturer for your equipment. Be certain to consult your equipment manual for details and schedules.

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  8. Is there a big difference in DV tape ?

    NO. That said a small difference can be important over time. It also depends on your use. If you are an occasional user any DV tape you can get your hands on cheap will work nicely. If you are a professional, or if you otherwise go through a lot of tape, then you have a good reason for using higher grades of tape.

    One of the issues is the tape mediums Signal to Noise Ratio. Sony and Panasonic make a consumer grade of tape and two pro grades. There is an improvement in each step of SNR. Sony has an advantage here, but it is difficult to compare. The difference will appear when you use the tape for a lot of rerecordings. That said, allow me to relate a personal anecdote:

    I have recorded the entire Babylon 5 series from the Sci-Fi channel on DV. To do this I used 5 tapes in SP mode which I recorded the the airings on. I then edited onto other tapes. Each tape was used at least 20 times in its entirety. Some ahve been re-used in the interim for other projects on camcorders. There is no visually perceptible difference from the first virgin recordings for any given tape. None.

    Another potential difference is the particle size on the tape. Even though these tapes are "Metal Evaporate" as opposed to "metal particle" that is just a description of how particles of metal are deposited onto the tapes. Both types of tape have metal particles on them, the ME ones are much finer. In the old 8mm days this affected the coercivity of the tape, or how easily they were coerced into a particular state. That matters less in the digital world. What remains is the wear a tape causes on the heads of your VTR.

    Finer particles will cause lower head wear. It is exactly analogous to the grit of sandpaper or an emery board. Coarse large grains wear quickly, finer small grains wear slowly and more evenly.

    Sony EX and PR tapes and Panasonic PQ tapes are roughly equivalent in this regard. Panasonic MQ tapes use a new process to create a very fine evaporate mist to coat tapes with called S-AME. If you run a lot of tapes, it will be to your advantage to use Panasonic MQ series tape. (This was previously named XB tape in North America.) Keep an eye out, I am certain Sony will answer with a similiar technical benefit, but not yet.

    Another issue is tape run length, which can affect tape thickness. 63 minute and shorter tape is 7.0µm thick while 80 and 83 minute tape is 5.5µm thick. The thinner tape presents more of a flaking hazard to your equipment and stands a greater chance of wrinkling or otherwise deforming. It is considered somewhat less reliable. I have had only positive experience with it however. I do recommend the highest available quality of tape when using 83 minute cassettes. (I use Panasonic MQ & XB tape presently.)

    Finally, different formulations of tapes have different coercivity and retentivity. Typically metal evaporate tapes, like MiniDV, have a high coercivity and poor retentivity. Pro grade DV tapes will usually have much higher retentivity than the consumer stuff.

    What about DVCAM and DVCPRO tapes ? Both of these, to my knowledge, come in one formulation from each manufacturer. I believe DVCPRO tape is metal particle tape. It should only be used in DVCPRO equipment. DVCAM tape is roughly equivalent to master grade DV tape, and can be used in regular DV equipment. Just remember that a lot of these tapes come in the large shell sizes, whereas most consumer equipment can only use small shell. (hence the Mini in MiniDV)

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  9. What are SP/LP modes ? Do they change the quality of my recordings ?

    SP and LP refer to the speed with which the tape moves over the tape heads. SP moves the tape at 18.812mm/sec and LP moves it a 12.56mm/sec. LP can give you a longer recording time. SP makes your recordings more secure, because more tape has to be damaged to make your image irretrievable or unaesthetic. In short, you have a risk of higher dropouts in LP mode.

    Both SP and LP record exactly the same signal and video information. They are of identical video quality in every regard.

    Allow me to relate another anecdote:

    In that Babylon 5 project I mentioned earlier, my final recordings were made onto Panasonic 33EB tapes in LP mode. I have over 100 tapes, each with one edited episode of Babylon 5. None of them, NOT ONE, has a dropout. Even after repeated viewings for some.

    The above has led me to a hypothesis: slower tape speeds may in fact help eliminate dropouts on DV media. It goes without saying that this could easily be a statistical anomaly. I certainly do not have a sufficiently large sample size to draw concrete conclusions, but I do have dropouts on SP mode. How might this work ? The slower tape may have less difficulty remaining in contact with the heads despite motion, tape path faults or tape irregularities. Remember: This hypothesis is just that, and is in contradiction of standard video engineering wisdom. I have not proven anything yet and my observations could be a statistical anomaly, also known as "dumb luck." If you have an important event to record USE SP MODE.

    There is one cautionary note: A lot of cameras and decks have trouble reading tapes recorded in LP modes on other recorders. This has to do with the extremely small size of the MiniDV tape and the specific pitch created by the heads and transport in LP mode. If you have to transport your tapes from one deck to another it is advised that you use only SP mode until you have had a chance to test the interchangeability of LP mode recordings on all your decks and cameras. If you only use one camera you should be OK. Just make sure to buy the next camera before the current unit breaks...so you can transfer your tapes to the new camera via firewire if need be to preserve your footage.

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  10. 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.

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  11. What is the difference between Digital8 and MiniDV ?

    These are both DV25 formats. DV25 is the definition of the video signal and compression for DV and Digital8 cameras. It is analogous to using the same typewriter on slightly different paper.

    There is no technical difference between what the recorder sections of Digital8 and MiniDV can do. They both record identically specified signals. They just do it onto different media. DV tape is designed for digital recording so it has some avantage. Nonetheless good quality Hi8 ME tapes produce excellent results.

    The main drawback of Digital8 compared to MiniDV is not the tape or recorders, but rather the cameras to which they are attached. These are generally inferior to MiniDV cameras and lenses. Most Digital8 cameras are really low to mid-range Hi8 cameras designed for lower resolution and SNR recording. If you record the signals from a high end DV camera, like a Canon XL-1 you will see precisely the same results as the MiniDV recording produced on that camera.

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  12. How do DV, DVCAM and DVCPRO compare ?

    Again these are all DV25 formats, with the same result as above.

    DV, DVCAM and DVCPRO all record exactly the same image. The difference again lies primarily in the camera sections. The situation is similiar to that of Digital8 vs. MiniDV. There are often much better cameras available for DVCAM and DVCPRO recorders to draw images from. The difference in camera quality is perhaps more dramatic. The images kind of run into a wall though where NTSC resolution and DV25 itself limits what the tape can record far more than even good DV cameras. (The Sony VX-2000 and the JVC GY-DV500 MiniDV cameras can deliver more lines, and have more pixels than NTSC screens offer.)

    So why buy these formats ? A lot of news programs need to do linear editing. DV and MiniDV do not stand up too well to all the jogging and shuttling done during linear editing. These formats can. These formats also have a longer theoretical shelf life.

    DVCAM and DVCPRO both run their tapes faster with more robust error correction than DV. DVCAM runs at 28.193mm/sec. Unlike my experience with DV SP and LP mode, these formats definitely reduce dropouts and extend shelf life compared to DV SP mode.

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