miniDV as a storage option?

[mattias]

actually, i just tried what i proposed, and i must say it held up pretty good. only very sharp, colorful and high contrast stuff, like titles, are really affected much. there is definately a very slight color shift in some areas, as well as some increased color bleeding, but the sharpness is still there, and there's no extra noise. as a matter of fact, the noise seems to be slightly reduced. the biggest problem are the ringing artefacts that do show up in some areas. they look like a mix of mosquito noise and bad edge enhancement, but they luckily don't show up until the fourth generation or so.

/matt

[This message has been edited by mattias (edited October 04, 2001).]

[Alex]

If BetaCam SP is not as good as Mini-DV, it has more to do with the lower cost N.L.E. systems not recognizing BetaCam SP as a better formatm, and not providing the necessary interfaces to handle all of the BetaCam SP quality.

In higher end systems, BetaCam SP can be put into a Digital BetaCam Deck, internally transcoded to digital, then outputted in serial digital, which is considered vastly superior compared to mini-dv firewire digital.

Mini-DV is also missing the top line of video information.

It can be theoretically rejected for broadcast because of this by broadcast stations.

In which case you would have to take the DV master, and blow it up one percent in an actual tape room with high end gear.

Just a little nuisance thing put in probably to appease Digital users who had spent lots of money on higher end digital betacam.



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Alex

[MovieStuff]

<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by mattias:

??? i thought you just said that you "ping-ponged" back and forth via "fire wire" between "mini dv" and your "dv card". anyway, if you did capture with an analog card (or digital with recompression), and converted back to dv for every generation, i'm *very* surprised you didn't see any difference after just a few pings and pongs.
/matt<HR></BLOCKQUOTE>

Well, my purpose is life is to keep surprising you, Matt.

Seriously, I guess I should have prefaced my report by saying that my capture board, alone, was over $6,800. It is a very high end board that has both analog and digital inputs and outputs. The DV input I had installed was simply an activation of the DV part of the capture board I already had. For the record, I was NOT using analog inputs. It stayed digital the whole way but had to be converted to the special codec that Reel Time uses, that's all. The conversion process is pretty invisible, apparently, as I did not get any ringing or other artifacts that you mentioned even after 10 generations. I guess maybe my experiment isn't typical of other boards.

Roger

[MovieStuff]

<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by Alex:
If BetaCam SP is not as good as Mini-DV, it has more to do with the lower cost N.L.E. systems not recognizing BetaCam SP as a better formatm, and not providing the necessary interfaces to handle all of the BetaCam SP quality.
<HR></BLOCKQUOTE>

Hmmmm. I'm not so sure. I've been a hard core disciple of BetaSP for years but my recent venture into miniDV has really turned my head and I've got probably one of the best capture boards on the market; beta component, composite, digital, SVHS etc. Not cheap by any means. The miniDV stuff always looks good no matter how many generations I go. I could never do that with Beta, even using component.

<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by Alex:

Mini-DV is also missing the top line of video information.
<HR></BLOCKQUOTE>

Not always true. I have a client that gives me tapes shot on both a Canon XL1 and some funky little cheap minDV cams. The XL1 gives me a full 720x486 image. The other cameras give me 720x480 which can leave a black border when viewed on underscan. Besides, there isn't video information missing. The video line is there. It's just black, so the broadcast stations won't (and don't) care, really. It's all way outside the safe area of the picture. Way, way out.

At any rate, when I take something that I've produced on my system at 720x486 and lay it off to miniDV and then bring it back, there is no missing line at the top. I get the full 720x486 image. So what you are saying is true about some cameras but not miniDV as a recording medium in general. If you feed it 720x486, that's what you'll get.

Roger



[This message has been edited by MovieStuff (edited October 04, 2001).]

[mattias]

you don't have to export it, since you already have it on the original tape. at least in fcp, it's simply a matter of just removing the files from your hard drive when you're done editing a sequence, and then recapture only the used portions when you need them.

as a matter of fact, i recently started capturing half resolution jpeg instead of native dv, which lets me fit half an hour of footage per gigabyte. the quality is similar to a good vhs copy, so it's more than enough for editing purposes. i then trim the project when i'm done editing, and recapture at full resolution. i've done this on two professional projects and a few hobby ones now, and it works great.

the advantage of using either of these approaches is that the time code is always kept intact, so no matter what happens, you can always go back to your original and recapture. make sure you back up your project file at least every day though, since it contains all your edits, color corrections and more.

/matt

[mattias]

roger, it doesn't matter what data rate you set for dv capture, since it's always fixed at 3.5 mb/s anyway. for some reason, lots of editing and capture programs (fcp and quicktime for example) let you change the setting without telling you it's completely useless.

the reason you didn't see any generation loss is because what you did was copying a file back and forth several times, not different from copying from one hard drive to another. unless you checked an "always recompress" box somewhere, or applied a null filter, in which case you should start noticing degradation after about three or four generations.

/matt

[Alex]

When I speak of BetaCam SP I am speaking of initial quality.

I wouldn't recommend going back and forth between BetaCam SP and Non linear a bunch of times.

But if you get a good digital encoding off of a BetaCam SP original you are doing fine.

I think what it comes down to is if you already own BetaCam SP, no harm no foul.

But if you are just starting out. It makes more sense to start with Mini DV.

In my analog suite, I can go Super-VHS to Betacam SP, then go another generation BetaCam SP to BetaCam Sp, and if I really had to, I could one more time, then go to VHS for release copies.

The digital noise reduction in the S-VHS decks is really good, and by doing it first generation to BetaCam SP, the Beta to Beta steps seem to hold up really well.

I welcome Digital as whole new opportunity with many applications. But I still get plenty of work that is all tape based and not necessary to do in NLE mode.

About the missing line of video on mini-dv.

I read that a producer was "forced" to enlarge the picture one percent to make for one video line that was missing.

I find that a bit harsh to make that big a deal out of one missing video line, but it can happen.


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Alex

[mattias]

> But if you get a good digital encoding off of a BetaCam SP original you are doing fine.

and this would be better than getting a digital encoding directly off the component output of the rank (which a dv deck would do)? seems like introducing beta sp into the equation gives you nothing but an extra generation loss. unless you want to use the beta sp copy for archiving, or for online editing, in which case it's a very good idea to use it.

/matt

[crimsonson]

Roger:

Can you explain in detail, your 'ping-pong' exercise? I am a little confused, as a DV user and advocate, bouncing between your computer and a dv deck through firewire should not do any change to the quality from the original footage- its a digital transfer. But I know I am missing something here... can you explain? Thanx....

Alex:

NO- DV cannot be rejected by broadcast stations because of two major reasons (there are some more...)
1. Some small market stations still use VHS - YES VHS... my company distributes to some of them for PSAs.

2. DV are up to specs for broadcast standard, that is why there is such thing as ENG Pro DV decks and some stations uses DV as their master format... The difference between that and consumer miniDV is 'labeling' and some features on the camera/deck itself and not the format. They are all using 3.6 MB/s, 720x480, 24 bit color res, 4:1:1 sampling, etc, etc.

The real only advantage of BSP over DV is the color sampling of 4:2:2.

Broadcast standards is really adhere to because it can give some kind of guarantee that what you shot and edited would look similar when its broadcast (IRE, Chroma, etc.) no matter which TV station.


Also- no matter what price you paid for your capture card, the highest quality is uncompressed - ~23MB per second... I think the cheapest card that does that is Toast. I might be mistaken. But that can be also moot for DV since firewire transfer of DV is exact copy, with uncompressed, theoretically there is still some info lost. With DV the compression was done by the camera or deck not by the PC (excluding recompression for editing purposes - fx, trans, titles, ets.).

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[Alex]

Before Digital existed...analog "generations"
were referred to as 1st generation, 2nd generation, and so on.

The idea was that first generation was terrific, but as you went to the second and third and so on, you would lose quality.

The new "digital school" of thought is that even first generation analog is somehow a loss!

I don't agree with that position.

It's important to note that mini-dv has a meg-bits per second data rate of somewhere between 3.5 to 9.0.

Digital Betacam is somewhere between 30-50 megabits per second. BetaCam Sp falls somewhere near Digital BetaCam.

Betacam has vastly more information per frame than Mini-Dv.

You really are allowed to actually play the analog signal back and immediately put it on digital without a loss of quality.

As long as the encoding is of high quality.

And as long as it is BetaCam SP.

VHS, HI-8, 3/4 can in fact lose just by playing the orginal image....but only if you use a cheapie deck and no time-base correction.

If you use high-end video decks, the improvement in signal quality is remarkable when it comes to 8mm video, HI- 8, VHS, and S-VHS, and as a result, the first generation tape can be encoded and just kept digital from then on.

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Alex

[This message has been edited by Alex (edited October 05, 2001).]