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Old November 6th, 2005, 12:32 AM   #1
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Avoiding dropouts- putting things into perspective

Perhaps this may help put things into perspective about whether or not it's worth buying expensive tape.

In my opinion, the following are things you can do to avoid dropouts. Having more expensive tape is probably low on the list, assuming they make a difference (they may not!).

- Avoid user error: Not hitting record, not labelling tapes and using the write-protect tab, recording over tapes.
- Let your tapes and camera acclimatize to temperature and humidity
- Avoid LP mode if possible. If you do use it, use the same camera to re-capture.
- stick with one brand? Or use multiple brands so that there's no critical mass of bad lubricant?
- Avoid shock
- Avoid recording DV on DVCAM.
- Avoid dust (i.e. don't open the miniDV tape). Dust does cause dropouts... I'm not sure if there are any good practices in avoiding dust.
- Camera is broken.

Not known if the following makes a difference:
-Avoid re-using tape? (Re-using a tape 50 times probably does increase chance of dropouts)
- Avoid 80 minute tapes?
- Buy better

Other sources of dropouts:

Broadcast dropouts:
Sometimes the broadcaster's video server will screw up and glitch up a picture.

Camera operator error

Wireless lav "dropout"


Even if you do get a dropout, you can paint over it. Audio dropouts are rarer and not so easy to fix.
But a single dropout probably won't make a big difference... they are hard to notice.
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Old November 6th, 2005, 09:07 AM   #2
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A dropout by definition means that there is no data being read from the tape for a short while. All camcorders and decks have error correction for small losses of data made possible by the data being recorded on the tape with error correction encoding. A visable dropout then only occurs when the loss of data is too big for the error correction to coverup. Errors can be caused by the oxide being removed from the tape( scraped off or not there in the first place, the head being lifted off the tape and not being able to read the data). Dirt on the heads masks the heads from the tape and leads to erratic reading of data with the error correction trying to recover all the time, usually on just one of the heads and thus results in the horizontal lines seen, some error correction effects will freeze the frame for a while untill the data stream can be read again etc. Playing tapes both scraps oxide off the tape but also polishes the tape and heads. Some of this dust can clog the heads and lead to dropouts. All tape has some form of lubricant in an attempt to move tape smoothly across the heads. Some of this lubricant gets left on the heads and tape path and is a potential cause of problems if mixed with dust or a lubricant that is not compatible ( Sony and Panasonic are typical conflicting lubricants) IF this mix gets stuck on the heads there will be a dropout and other problems( I have personal experience of this mix permanently damaging a tape). This seems to have more effect on camcorders that are not used all the time. Decks in a work environment that are on all the time with a large tape throughput and auto head cleaning seem to fair OK.
The message is clear, use ONE brand of tape from the first time you use the camcorder, keep the heads clean. Thats it.
What you record on tape is not important, DV, DVCam are essentially the same what the label says on the tape is not important just as long as you understand that DVCam equipment runs 50% faster so a DVCam 40min tape is the same length as a 60 min DV. One reason that DVCAm equipment have more resistance to dropouts is that for the same physical size of tape defect less of the data is effected and the error correction circuits have a better chance of recovering the data ( a 50% or better chance in fact)

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Old November 6th, 2005, 02:28 PM   #3
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By recording DV on DVCAM, I mean recording DV material over DVCAM material. At the crossover points, you will get dropouts (and a timecode break on the end) since the deck/camera has to change tape speed on the fly.

2- As far as re-using tape goes, have you actually tried re-recording over a tape many times?
Some people report doing 50 passes over a single tape with no visible dropouts.
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Old November 7th, 2005, 11:59 AM   #4
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I understand now what you meant by DV recording on DVCam, yes there will be a signal loss as the deck changes speed ( technically not a drop out ). But why would you want to do this? If you always start recording 30sec or more before you need to and run on 30 secs after end of the shot you will not have a problem loosing any of the shot. You could of course reuse the tape of either type in the other camcorder from the beginning with no problems.
Yes I have reused tape many times, though for most I keep the master and do not reuse after capture to PC for editing. I have not had any problems with the reused tapes though the reuse may only be 2 or three times. Now as far as playback is concerned some of the tapes have been played way over 50 times. From my perspective the main thing to do is STAY with ONE brand( in my case Sony Premium for DV and HDV).

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Old November 7th, 2005, 02:42 PM   #5
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And always remember to take the lens cap off.


Someone had to say it.
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Old November 26th, 2005, 05:11 PM   #6
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Quote:
Originally Posted by Glenn Chan
Some people report doing 50 passes over a single tape with no visible dropouts.
No visible, but maybe audible.
I've over-recorded (for the first time since the first recording) a TDK DVM60 tape, and there are small (very small), but hearable dropouts in the audio. It just disappears for a very short, but audible period - while the video is all right.
I use 16bit sound recording, if that matters.

Let me provide you the waveform visualization and the sample itself so you can watch & hear this oddity.

I use Sony Premium tapes almost all of the time. TDK just slipped into my hand when I was looking for something to record on - could this be the cause?

Or maybe it's the fault of the FireWire controler that I'm using? Because it's some integrated-into-mainboard sort of one. Although, there were 0 dropped frames. I was capturing with DVIO.

Quote:
Originally Posted by Steven Davis
And always remember to take the lens cap off.
I was "filming" with the lens cap on. However, the only thing that I cared about, was the sound.
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Old December 13th, 2005, 04:53 PM   #7
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Ron,

I use the Sony Excellence tapes. Have you ever had any trouble with Sony brand tapes?
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Old December 13th, 2005, 08:19 PM   #8
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I use Sony Premium tape all the time for DV and HDV. I keep one of my older camcorders for non Sony tape. I cannot recall a dropout in the last 4 or 5 years with Sony tape.
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Old December 14th, 2005, 09:14 AM   #9
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Occasionally while playing back Sony tapes (shot with my XL-1s) in my JVC deck, I don't have any audio dropouts, but I hear what I can only describe as a "tingle" in the audio. It's like digital noise in the audio, or static, but the audio doesn't drop out. Any thoughts?
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