MiniDVs as a Backup Medium? 39
Matey-O asks: "Having purchased a MiniDV camcorder for the impending arrival of my twins (I suspect a majority of camcorder sales HAVE to be bought by new parents), I also purchased the firewire connection kit. Based on the software estimates on how much uncompressed video can be stored on the harddisk, it looks like a 60 minute MiniDV cassette holds about 15 Gb. Since the PC can control the camera, and the transfer is billed as lossless, has any work been done on using MiniDV as a backup medium? One Cassette looks like it'd store ALL of my important info, and at $5 per, it'd be pretty economical too." Reading this definition, it looks like the submitter may be mistaken about the 15GB size, and the Backfire pages at Sourceforge indicate a more realistic figure of 12GB. Backfire itself looks like it might be the project the Matey-O wants, but the last update is from April of 2000. Has anyone taken up this idea and tried this particular backup path, before? Is it a practical alternative to your standard computer tape drives?
tape backup (Score:5, Interesting)
Re:tape backup (Score:1)
MiniDV is not DAT (Score:3, Informative)
Re:tape backup (Score:3, Informative)
Re:tape backup (Score:2)
Data-grade tapes are screened for this sort of thing, though even that screening isn't perfect; for video grade tapes, where that blotch would merely become a blip on the screen, quality control is a lot less strenuous, and you might find strings of such anomalies, which would probably ruin any chance of data recovery.
On those VHS VCR tape backups, which were mentioned in another response, I believe the gizmo recorded triple-redundant data (each block written three times) in order to compensate for these sorts of problems. It didn't always work.
Re:tape backup (Score:2)
Of course, if the errors really are on the tape from the start, then detecting bad areas of the tape and writing around them is even better!
Re:tape backup (Score:1)
Re:tape backup (Score:1)
Personally, for stuff that you backup regularly, I'm recommending hard drive backups to friends and family. Get an extra drive on a removable tray when you buy new machine. One night per week, copy the whole mess over.
Re:tape backup (Score:1)
Re:tape backup (Score:2)
dvdbackup (Score:5, Informative)
Re:dvdbackup (Score:3, Funny)
Re: dvdbackup (Score:3, Informative)
Re: dvdbackup (Score:1)
Just be careful with video editing software that supports batch capture. Media 100 (our professional video editing software) supports batch capture over firewire, and while it worked fine on the Pro hardware, the consumer equipment wasn't designed for control based on the timecode (not as accurately as the software was looking at anyway).
It resulted in the camera shunting back and forth, mangling the tape, and it can't have done the camera any good either.
Digitising a clip at a time worked fine though. Took forever though. I'm just glad that batch digitise worked well on our 184 minute DV-CAM tapes!
Err, 80-minute MiniDV tapes? (Score:3, Informative)
The submitter is right, I think. The data capacity for a 60-minute MiniDV tape is about 12GB. However, for 80-minute tapes, the nominal maximum data storage capacity is 80/60 * 12 = 15GB per tape, which might reduce after FEC overhead to 12GB per tape.
Re:Err, 80-minute MiniDV tapes? (Score:2)
I then corrected it to 60 min for a DV tape.
It's why I said 'roughly'
You beat me to it... (Score:3, Informative)
In a word: No (Score:1, Insightful)
No offense... (Score:2)
- A.P.
Re:No offense... (Score:1)
What kind of crack are you smoking? (Score:3, Insightful)
Short answer: NO .
Longer answer: I'm a film student, I've been working with MiniDV a lot the past few semesters. MiniDV, especially with the cheap ($5!) tapes, is very prone to dropping frames; you lose a frame on a good shot and it's an annoyance, but translate that into data backup and it could mean losing a piece of a file. How much do you value the data you're backing up? If you're bothering to back it up, you probably value it more than that.
MiniDV has its flaws as a video format, so much so that Sony and Panasonic have come out with their own formats based on it to correct some of these problems (DVCAM and DVCPRO respectively). And that's what it was designed to do, and it still can't do it well. It wasn't designed for data storage. Use something that is.
You can do something the cheap way, or you can do it the right way. People who value their data choose the latter for obvious reasons.
--- I'm not a real anonymous coward, I just play one on TV.
Who's smoking? Frame drop != data loss (Score:5, Interesting)
A dropped frame is a visual symptom. It doesn't tell you how much data was lost. A dropped frame doesn't necessarily mean all of the data or even any of the data for that particular frame is actually unreadable on the tape. Dropped frames have many temporary causes like dust particles on the magnetic tape, faulty cables, cosmic rays or strong RF interference hitting the electronics, buggy software, drivers or slow CPU in the case of computer DV decoding, etc. Granted, it could be a patch of tape is really damaged, causing tens or even x hundreds of bits to be lost.
Whatever the cause, a camcorder's builtin error correction can usually recover from small amounts of bad data. That's good enough for making videos but not for making backups. By using an additional layer of Reed-Solomon error correction as used in Rsbep DV Backup [netic.de] bad data up to 12240 consecutive bytes can be recovered, not counting any additional lower-level bad data the camcorder's internal FEC may have seen and corrected. The Rsbep guy found he could make up to 0.5mm diameter pinholes in the tape without losing data! I've seen professional data-grade backup tapes lose data after damage to a much smaller spot of 0.2mm diameter. I would say backups on MiniDV with RS error correction are feasible and cost-effective at 4USD/10GB. At 3.6Mbps, DV backups are also fast.
IANAFS but I've used a lot of different MiniDV equipment and I've never had a problem like yours with dropped frames. Maybe your DV camcorder has dirty/misaligned/worn heads any of which could cause dropped frames.
Re:What kind of crack are you smoking? (Score:1)
A good backup solution would be a DDS Dat drive from my experience. Tapes are generally cheap (15-20 CDN for DDS-3 tapes, which offer 12GB uncompressed), and the tapes are certified for backup use and support proper error correction, as the DV format does not have great error correction for data (due to how the data is structured on the tape for video vs raw data). The downside however is that a DDS drive can be expensive for a newer DDS4 model.
Best PC firewire hardware for Linux? (Score:1)
To anyone using Firewire with Linux, which PCI card or motherboard would you recommend as the best most Linux-compatible solution to get Firewire ports?
Anything OHCI compliant (Score:2)
If it says, "VIA chipset", then it's almost guaranteed to be OHCI compliant.
The only other 1394 host implementation I know about is the TI PCILynx chipset, and TI themselves have been moving towards OHCI. PCILynx chips are semi-supported under Linux.
Re:Anything OHCI compliant (Score:1)
I'd like to find a Linux-supported replacement for my current card which has all of the following on a single addon card:
Unfortunately, Fast Electronics [fastmultimedia.com], the only maker I know of such multifunction single cards, only supports Windows and doesn't release programming info. I'd prefer not to use up 2-3 PCI slots by having multiple cards to do separately the tasks of video digitisation, video output and Firewire I/O.
Hmm... (Score:2)
If you go to Best Buy though, Dazzle sells an external analog video digitizer. (Analog to DV and I believe vice versa too.) Since it's DV it should work with any program that groks DV. (Kino, Cinelerra on Linux)
MacOS X (Score:2)
-psy
The problem with MiniDV... (Score:1)
Re:The problem with MiniDV... (Score:1)
and stop stealing my signatures man.
CD-R/CD-RWs aren't all that reliable either! (Score:1)
I don't think anybody will ever have a CD-R last as long as a tape can without a hiccup, even in the best storage conditions, meaning no sunlight, relatively constant temperature, controlled humidity, etc.
CD-R ~ 5 years before you will start getting some unreadable CDs out of a fair sized batch
Tape ~ 20 years before the tape itself degrades to the point where you'll notice
Now, a pressed video cd, on the other hand, would probably last a long time...
Re:CD-R/CD-RWs aren't all that reliable either! (Score:1)
Time will always be an enemy when backing up data, as nothing lasts forever, so you always have to be one step ahead (and backup your data regularly before its too late).
Re:CD-R/CD-RWs aren't all that reliable either! (Score:2)
Tape ~ 20 years before the tape itself degrades to the point where you'll notice
I'm assuming that a tape that lasts 20 years before noticeable loss is much better than a low cost bulk tape. You should compare it to a similar CD-R.
A high archival quality CD-R costs about $1.50/unit and has a shelf life of over two hundred (200) years. This is significantly longer than a production pressed CD is expected to live. Archival CD-Rs are the way to go.
deja vu (Score:2, Informative)
not nonsense (Score:1)
Heck, with a really redundant error correction protocol, make it 6 gigs per tape, at $5 a tape, and "lots" of folks have these camcorders... it's a great idea!