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DV Backup

 
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zerodefekt



Joined: 08 Mar 2004
Posts: 2

PostPosted: Mon 8 Mar 2004, 6:00    Post subject: DV Backup Reply with quote

First off, thanks for the great guides on your site - been very helpful.

I have two reasons for encoding to MPEG2. First is to make DVD's of some of my home movies that I've previously edited and secondly to make backup's.

As far as backups are concerned I want to encode the DV video with minimum losses so that I can use the encoded video later for editing/rediting with minimal loss of quality (generation loss). I would think encoding using a very high bitrate (>8Mbps) in CBR using no B frames would be optimal for this purpose. What settings do you suggest?

However, when using a high bitrate and a typical DV tape length of 90 minutes, the encoded video won't fit on a single 4.7G DVD-R, this is not a problem as such, however I need to be able to split the m2v and (encoded) AC-3 (using BeSweet) / PCM audio into 2 files to write to DVD-R. What tools do you suggest I use to do this? I need a good m2v (mpeg2) splitter and AC3 / PCM splitter, preferably working on both at the same time to eliminate synchronisation problems.

What AC-3 bitrate would be best for archiving? Given the same reasons as above (minimal quality losses for possible future editing). Or should I use PCM?

Appreciate any suggestions. Thanks.
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RMN
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Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Mon 8 Mar 2004, 15:47    Post subject: Re: DV Backup Reply with quote

zerodefekt wrote:
As far as backups are concerned I want to encode the DV video with minimum losses


Er... why not keep it in DV, then? Just make a copy of the tape. Magnetic ME tapes are likely to last a lot longer than recordable DVDs.

MPEG is not a good format for editing, whether you use B-pictures or not. P-pictures also use temporal compression, and need to be recompressed after cutting. If you want to use MPEG for editing, you should use I-pictures only and a bitrate above 20 Mb/s. But for that, you might as well keep it in DV (25 Mb/s) and avoid any quality degradation.

DV was invented after MPEG-2. If it was possible to get the same quality and the same flexibility out of MPEG at that bitrate, then DV would be based on MPEG-2.

RMN
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zerodefekt



Joined: 08 Mar 2004
Posts: 2

PostPosted: Mon 8 Mar 2004, 17:20    Post subject: Reply with quote

Quote:
Er... why not keep it in DV, then? Just make a copy of the tape. Magnetic ME tapes are likely to last a lot longer than recordable DVDs.


I haven't really seen much info on DVD-R lifetimes. I do know that tapes last quite long, just not sure how how long DVD-R lasts.

Good point on MPEG2 editing, didn't realise that. Of course, thats why I asked Wink

Thanks for the reply...
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RMN
Site Admin


Joined: 04 Feb 2003
Posts: 587
Location: Lisboa, Portugal

PostPosted: Tue 9 Mar 2004, 4:36    Post subject: Reply with quote

The reason you haven't seen much info about DVD-R lifetime is that there isn't much info about DVD-R lifetime. Smile DVD-R has been around for a relatively short time, so all "data" is just guessing.

CD-R, on the other hand, has been around for a long time. And while some of them seem to last reasonably long (meaning over 10 years), some start to show errors after less than one year (and this is without any scratches). DVD-R is less resistant than CD-R, although I suspect that on average it has better quality control.

So I wouldn't really trust DVD-R as an archival medium.

Nor do I trust tapes, BTW, although I trust them slightly more (banks, etc., still use tapes for their data backups).

If you want something to last forever, you have to be prepared to copy it to new media every now and then (ex., every 2 or 3 years). And that's the beauty of digital. You can copy it over and over and, as long as you don't recompress, there's no quality degradation.

RMN
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