I'm sorry to hear that the ribbing has gotten out of hand. Still, It seems that the first adversarial comments came from you:

“I have come to expect the consumer responses on this forum- the masses seem to have no idea what they are talking about!”

I may have missed some antagonistic comment, either plain or inferred, so it is really immaterial. What is important is the presence of quite a few people who are relatively new to video/film production (myself included) who could use a resource with a wealth of real-world knowledge. Hopefully, you’ll stick around to offer advice, and take the usual forum chatter in stride.

Something I should have added in my previous post. Its the chroma component that has different compression in a camera recording DV versus DVCAM. This explains why d1editor can see a difference, there's simply more dynamic range available.

The camera can do this because of the higher writing speed of DVCAM.

The other difference is that the audio on DVCAM is locked to the video.
Shooting on DV, usually during fast motion the audio may get several frames out of sync with the video, again not a major issue.

IMHO DVCAM large format tapes are just more robust, the build quality is better and the drives are stronger and the longer record times are a big plus, but it costs more per minute.

DVCAM and DV/Mini-DV are both 5:1 compression (25mbps) formats, as is DVCPRO. None of these compresses chroma any differently than the others, with the exception of 625/50 (PAL) DVCPRO, which is chroma sub-sampled 4:1:1. This is how DVCAM and DV/Mini-DV are sub-sampled in 525/60 (NTSC) video. DVCAM and DV/Mini-DV use 4:2:0 sub-sampling for 625/50 (PAL) video.

DVCAM, DV/Mini-DV, and DVCPRO are all 6.35mm-wide tape formats with a few differences:

=======
DVCAM uses a 15-micron track pitch and locked audio. It uses metal evaporated tape.

DV/Mini-DV uses a 10-micron track pitch in SP mode and a 6.7-micron track pitch in LP mode. Locked audio is not required. Like DVCAM, DV/Mini-DV also uses metal evaporated tape.

DVCPRO uses an 18-micron track pitch and locked audio. Unlike DVCAM and DV/Mini-DV, DVCPRO uses metal particle tape, which is more expensive/robust.
=======

I agree that DVCAM tapes are of substantially higher quality, in the general case, than Mini-DV tapes, but there are no differences in video quality in the absence of media error. Another important thing to note is that the most synchronization error allowed in unlocked audio is +-1/3 of a frame, and it should not be cumulative. If you are experiencing synchronization issues with your hardware on the order of multiple frames, then it is operating outside of specification (i.e. it is made by Canon).

Don't know if I'll be able to contribute much to this discussion, but I'd like to point out one thing: setup.

Some higher-end cameras, and DVCAM decks, give you the option of adjusting "setup" on the analog outputs; that is, whether your "black" level is 7.5 IRE (NTSC/USA) or 0 IRE (NTSC/Japan) or something else. It is possible the that the analog output on d1editor's DVCAM deck defaults to one type of setup on DVCAM playback, and something else when playing back DV. That would certainly account for the appearance of "richer blacks" output from one format, even if the actual bits on the tape were identical. Moreover, the Sony PD150 also has a menu option to add setup digitally before recording to tape (which is nonstandard and should not be used, according to Adam Wilt), so that is one more potential variable.

http://www.adamwilt.com/DV-FAQ-tech.html#Setup

I'm told that my previous post on this may be slightly incorrect, it maybe completely wrong as well of course!

On a PAL camera there is no difference, the difference in sampling only occurs on NTSC cameras. This is obviously a pretty confusing subject and one I'm sure Sony's marketing dept wouldn't want to see cleared up either.

Certainly what mchaboud said in his last post would seem at some variance with this and as I work in PAL either way I can breathe easy!

Somewhat related to the thread, but a little off topic...

Anyone know how long a mini DV tape is suppose to last once recorded? It is afterall tape, and I was wondering if it gets brittle, tends to break, that kind of thing and if or not you can over do it replaying it over and over like with VHS tape. I know the quality of what's on the tape sould remain, but does the tape itself get more fragial over time and if so how much time. Also best way to store it for long term?

TIA!

I was told by a few dealers (panasonic, sony and JVC) that the best way to preserve a tape is:

1. Use plastic casing, like the ones you get when renting a movie (with the snaps), Reason: because dust cannot accumulate and get inside. The mini-dv case you get when you buy you tape is not good enough.

2. Store you tapes standing up. Don't know why.

3. Of course, store in a nice cool not damp area, no direct sunlight, etc..

I have about 400 tapes stored in this manner, mostly all VHS tapes and are in excellent condition..no dust accumulation...except for the ones I stored in a VHS cover sleeve. Some tapes are about 17 years old and great video quality.

Hope this helps.

Storing them standing up is quite important. It doesn't matter which edge you stand them on, but they should be resting on a narrow edge rather than on the largest sides.

When tape is wound on the spindles, especially rewinding or fast forwarding, often the tape won't wind evenly. Occasionally some of it may not line up with the rest perfectly and you'll have edges sticking up above or below the rest of the "pancake". If you store the tape flat on the larger sides, the weight of the tape can press on these stray edges and crinkle them. Not only does this damage the tape, but each time it happens it makes it more likely to be worse the next time the tape is wound.

It's also a good idea to store tapes after playing them to the end (at least the end of what you've recorded), then wait to rewind them until the next time you need to play it. Playing a tape usually lays the winding smoother than rewinding it, so you lessen the crinkling problem mentioned above. Rewinding it just before playing also loosens and flexes the tape so it will play better.

I used to work in a video rental store and always had to laugh at the "BE KIND - REWIND" stickers my boss had me put on all the tapes. It was exactly the opposite of what we should have been doing to best preserve the tapes. Besides, if you leave the tapes at the end after watching them, then everyone has to rewind them before playing ... and no one has to complain about rewinding it twice! Oh well ... i'll never change the world ;)

That's a tortured comparison of apples to oranges and you know it.

But seriously, support the claim that DV and DVcam tapes give a different picture from the same camera. I'd take a real explanation seriously.

Rob

Thanks D1,

That's a much better answer and well supported. So the next question is, if it's just data being writ to the tape instead of an actual signal, what is it about DV tape that changes the data? Or is it actually an analog signal on the tape?

Watch out for using the "I've been (fill in the blank) for 20 years" argument. I just had a contractor around who used it and I had to ask him why, in 20 years, he'd never learned to do a particular task right. Hell, it doesn't matter if you're right or wrong for a MILLION years. Your still right or wrong.

Rob

I'ts very true that outdoor light can change fast. I've spent many a day making chalkmarks at shadow lines while we were trying to get a shot off.

Still, it seems like if you were looking at the picture that critically you'd notice the light changing. At least you'd consider it.

I'm more than willing to accept that D1 saw what he saw. The test is reproduceable. Others should try it.

Rob

When in doubt, do a camera test (as you did). Originally, that was the at least part answer I was looking for.

Camera and stock tests are a time-honored procedure and reading the tech docs are no substitute for experience (although they can help explain why you see what you see). So if people want to know for sure, shoot some tests in a few lighting situations.

Watch out for changing bounce lights in daylight.
Watch out for changing light angles in daylight
Watch out for stray light falling on the lens.
Control the variables. The only thing that should change is the tape stock.

Rob

Setup would definitely account for it. Especially if they were A/B switching on the monitor back in the edit room. If that's the case then there were two decks and one might have been the camera. Additionally, the scopes would have been plugged into an analog output

So, if you're using two decks for the two tapes maybe it makes sense to compare then swap the tapes across the decks and compare again.

Setup on prosumer camera screws a lot of people up.

Rob

I keep telling the rental guys that I rewound their DVDs but I never get any praise. Not even a thank you. Should I store it on edge?

Rob

Rmack, proper storage of DVDs actually requires generating a fractal 3.7145932 +/- 0.0000023% dimensional environment. The DVD must be suspended inverse laterally with the spindle hole projected approximately 0.015 phase into the future to correct for sagging. The exact phase adjustment will depend on the viscosity of the ink used for printing the surface of the DVD.

Hope this helps. ;)

Does that means that if I want to burn wy own DVDs, I'll have to actually *print* a label on those to be able to store them?
How can I overcome the situation? ¨:/

I don't think that anyone has any doubt that D1 could have seen some difference in his A/B'ed footage. The assertion that his experience in a pseudo-controlled setting somehow bears more merit than the standards laid out for the formats is what I have a problem with.

"instead lets use an Ikegami HL-59 Digital Camera with 900 lines of resolution.... we send the signal to VHS and Beta SP (both analog); and we send the same signal to DVR 2100 (D1- 601 machine) and a mini DV camcorder .... from what you say- the camera is a constant, compression between VHS and Beta SP are the same--- then the quality is the same...both the 2100 and the DV camcorder are digital, so they should be the same since tape format does not matter... so we should start broadcasting a VHS form a digital camera!"

This series of broken sentence fragments shows a fundamental misunderstanding of the differences between digital and analog recordings. Anyone who asserts that DVCAM and DV/Mini-DV video streams are different is wrong. DVCAM recordings can be transferred to DV/Mini-DV and will remain digitally identical, locked audio and all. The reverse is also true.

Sony went out of their way, on some devices, to prevent cross-format copying. This was not a technical limitation but, rather, a marketing decision.

Oh yes, I know that D1's counterexample makes me doubt all sorts of things about...

What I want to say, though, is that shooting tests is a very good thing. When the technical assumptions and real world tests reinforce each other it inspires a lot of confidence.

I ended up doing the same thing with aspect ratios just to demonstrate that 720x480 really does square down to 654.5x480. Now I'm doubly confident.

I'm more convinced that D1 was seeing setup added to the analog out. Best to scope out bars recorded to tape before doing a subjective judgement. I've seen the wanky setup output on PD150s fool people with more than 20 years experience.

Rob

Wow! Thanks!

I was thinking of getting a DVD burner but it looks like I'd better get a matching printer too.

Do typos on the label damage the DVD over time?

Rob

D1,

Sorry to make you angry and if I was inflamatory please believe that I was trying not to be while still asking the questions. I'm afraid that at this point the responses may be running together for you as far as who said what.

Actually, we agree on a lot here-that testing is worthwhile, for one thing. I write a bit of technical documentation and find that I always need to get a few sources that agree before I commit.

There is a big difference between analog media and digital media. We all expect to see a difference between Beta SP and VHS. Furthur, it would be hard to do a decent test between the two. Probably you would want to take signal out from one and only one camera to both a beta sp deck and a vhs deck.

The analog test doesn't compare to the DV test at all.

The original question seemed to be, given a camera that can use DVCam and DV tapes, is there a difference?

We know there is a difference in tape robustness. On that we agree.

As far as picture difference, we (all) don't agree. The "by the book" argument says that the digital signal is just data. As data, it's the same data whether you record it on DVCam tape, or DV tape, or a hard disk, or a CD, or a floppy disk. This means that you can use a hard disk recorder and get the same picture you would get on tape, BTW.

The test and look argument says that, regardless what you believe should be the truth, the best way to tell is to do a camera test, making a subjective judgement by eye and an objective judgement by scope. To control the camera test one would use a single camera and deck in several lighting situations. You would then either view the images played back form the camera OR, if you want to AB the images you would view each image in each deck to be sure that the results were the same. You want to eliminate the possibility that the deck output is a factor.

I cannot argue against doing camera tests. They're a very good idea. Several people should do them independently. Maybe the results would agree, maybe not. If they do agree then we'd want to know WHY they agree (which was what I was hoping to learn in the first place).

Of course, when you're trying to decide what stock to use you can't have independent testers. You just do the test and decide. The "by the book" camp says you couldn't go wrong. The test and look camp says you choose what looks best. It's not like anyone is saying you made the wrong choice-you made the best choice.

Rob

<rolled eyes> It doesn't take a technical manual to understand that interoperability between devices would be completely impossible in the absence of a regimented mechanism for recording/playback. Given that requirement, the presence of such a mechanism, and the real-world results of users, novice or otherwise, it appears that a problem must exist in the keyboard-chair interface. This diagnosis is strongly affirmed by the posts above. </rolled eyes>

D1, I tried to give you the benefit of the doubt, but you just continued to fight about this one. The proof is not in your results. The proof is not in 20+ years of experience. Granted, digital is not digital, in that the video stream on a VCD is not the same as the stream on a DVD, but, in this case, you asserted that there was a difference between DV/Mini-DV and DVCAM other than track width and tape speed (cited by mountainman). Besides locked/unlocked audio requirements, there is no digital distinction.

You made your contrary statements in an authoritarian manner, based purely on personal observation (read: error), and you initiated abusive posting with your "I have come to expect" post. If you witnessed some real difference, it was most likely due to user error, rather than some sort of interference from the "video gods." Arguments that amount to throwing one's hands up in the air and saying that one has no idea, after claiming otherwise, are not very effective.