DV Info Net - Mini Dv Tapes

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I've heard conflicting opinions in the past on how long mini-dv tapes last. Some have said they last a lifetime and can be viewed 100 times before any loss in picture quality and others say that they will last about 10 years and start to lose quality after 4-5 playbacks. I could copy them all but it would be quite expensive. Any help would be appreciated.

Thank you,
Tony

Hello Tony,
Do a Search on this, as it's a relatively frequent topic.

Here's one recent thread.

I find that they lose quality (drop-outs) after playing them back roughly after 5 times.

You guys are crazy or something...just kidding, but seriously, i've recorded over tapes atleast 6 times, and played them back countless times, and just in my little $400 Panasonic, and never experienced ANY dropout...

Then you are lucky, Alex.

We're talking about playing back the same footage, and not re-using a tape. I don't know how many times you can re-use a tape. I've read different things---and I store all my old tapes because I want to preserve the footage---therefore I don't re-use tape.

Wait a minute, you're telling us that after playing back a tape 5 times or so it begins to lose quality? That's insane. If that's true then MiniDV has got to be the crappiest digital recording medium ever invented. That can't be right.

It is the nature of magnetic tape to lose some signal strength over time. Playback accelerates this signal loss. With digital signals, the observed effect will be a gradual increase in data read errors. The visual effect is nil, untill the read errors exceed the built-in error correction capability of the DV format.

I haven't had any problems and I've played back the same tape at least ten times in a row when making copies of special event videos and special interest videos and I haven't had a problem.

In fact, I have one D8 tape that I've played back at least 50 times and I haven't had one dropout on it and I don't believe that's the exception.

Maybe someone who works at a news station and edits with dv tapes can chime in on this one because news stations put a lot of wear and tear on their tapes by scrubbing them all the time and repeatedly playing them back while editing. They should have a pretty good idea if a tape wears out after a few playbacks.

Ben Lynn

I do not post this to promote the use of Sony's DVCAM tape or Tape Resources (which is a good vendor). But I received a DVCAM promotional card from Tape Resources today which advocates the use of Sony's DVCAM tapes for both DVCAM and miniDV cameras. I transcribe it below because I think it shines some light on the key reliability and durability factors surrounding tape from a manufacturer's (Sony's) perspective. Since tape is a very frequent topic here, and one which we all have in common, I think it will be of broad interest. I transcribe it here strictly for informational purposes and do not necessarily advocate the use of DVCAM tape for miniDV work. (I actually think the extra expense is unnecessary.) The information on the card compares DVCAM tape to standard DV tape.

Quote:

Lower Dropout Rate: DVCAM media has a 50% lower droupout rate, and a 4-5x improvement in error rate margin.

Maximum Durability: Although both DVCAM and DV use DLC technology, the DLC layer for DVCAM is optimized for maximum durability. It offers a 25% higher level of strength for the type of still frame, multi-pass editing used by professionals.

Still Frame Evaluation - The recorded signal level of DV showed noticeable loss after 20 minutes in pause. DVCAM held signal level even after 60 minutes.

Editing SImulation - Editing tests have shown that DV media begins to show picture disturbances after 150 passes. DVCAM shows no noticeable disturbances or loss in picture quality after 150 passes.

Improved Physical Stability: Magnetic tape is susceptible to expansion and contraction due to temperature and humidity variations over time. Excessive shrinkage disrupts the position of the recorded tracks and often results in "off-tracking". This simply means the recorded tracks have shifted and the play head cannot accurately read the information. This type of shrinkage is usually associated with long-term storage.

To minimize the potential of tape shrinkage and recording/playback problems, DVCAM media exclusively uses a base material with 50% less shrinkage. The benefit is added reliability and confidence that the recorded material is there and will play back even after years of storage under reasonable storage conditions.

Tighter Width Specifications: DVCAM and DV have a width of 6.35 mm (1/4"). The more uniform the tape width, the better the record/playback stability and compatibility between recorders. DVCAM width is held to a tighter tolerance to offer a higher level of reliability and compatibility.

DVCAM uses an ultra-accurate slitting machine to assure correct tape width.

Maximum Picture & Sound Stability: Friction increases between tape and recorder heads after repeated passes on the tape. DVCAM media has a significantly lower friction coefficient than DV. For the professional, this means greated recorded signal longevity, higher reliability, increased durability and overall improved performance.

BTW, if the reader of the card is still not sold on technical merit, Sony is offering a free golf shirt with every $500 order of this stuff.

"DV media begins to show picture disturbances after 150 passes"

That's 150, not 5. That's more like it.

Ben wrote, "In fact, I have one D8 tape that I've played back at least 50 times and I haven't had one dropout on it and I don't believe that's the exception."

That's because D8 is more robust. It runs at a faster speed plus it is 18 microns, I seem to recall, than miniDV's 10 microns.

You can check up on the formats here:

http://www.adamwilt.com

A note on the life of magnetic recording. Played some audio recordings I made in ~1965 last night, they were on Ampex-branded white box, reel-to-reel tape. Sounded about as good as they did back then.

MiniDV is similar to DATs. These have excellent re-usability, trust me on that one. Sometimes I would record over and over and over. The tape is less the issue than the recorder/player is.

Keep in mind that MiniDV tape is ME (evaporated metal) formulation. Those of you who have shot Hi8, may recall that it was the formulation most prone to most prone to drop out.

While tape has improved significantly over the past 10 years, I suspect that the jury may stil bel out on long term, drop out free life of material recorded on ME tape.

Peter, I've found 5 to 7 playbacks and I begin to see dropouts. Of course, this could be due to the cheaper cams with cheaper heads I mainly use. With my MX300, I have not noticed any drop-outs yet.