A Question, About Compression .... Please Answer at your Discretion

[Radical Posture]

Thank you for this forum ! Awesome ... so glad it found me !

I have 15 x DV tapes ... they will each be about 12 gig each when imported into iMovie.

A local videographer suggested that I should get him to record all those tapes onto 5 x DVDs (3 tapes on each DVD). That is compress, 36 Gb (3 tapes) onto 4.7Gb (1 x DVD). He then says that I will be able to edit from each of those DVDs. Of course, this means that I'm working with smaller files and I will not have to transfer 15 hours of tape onto the Mac.

SO, I guess that I will be able to edit from those DVDs, but, quality is the issue.

If I do receive a DVD with 3 tapes compressed to 4.7Gb, what is the quality like ? Good enough for viewing ? Good enough to edit ?

I will need to edit this footage and then burn it to DVD again.

I've scanned other posts on the forum, but, am not completely satisified with my understanding of compression and loss of quality.

Will the naked eye see this compression, and the re-compression ?

 

[xstep]

I can't see how you wouldn't lose a great deal of quality.

If the DVD the videographer is talking about is a DVD playable on a regular DVD player like a Hollywood movie with MPEG2 encoding, that would be one highly compressed video. From that you would have to convert the VOB files to something editable in your editing software. Finally, you would export your final edit and bring it into iDVD (likely) which would convert it again to MPEG2.

Even if the DVD was to be a data DVD with say QuickTime movies using H.264 encoding, I still think quality will noticeably suffer.

Just buy a big drive to hold the 15x13GB videos with space left for editing. Say, a 500GB firewire drive.

If you end up doing the DVD thing, at least insist that the person use dual layer DVDs for the same three hours so that you can get better quality if he/she doubles the bit rate.

 

[Indifferent]

If you're source material is transfered through dvd and thus heavily compressed. You'll louse not only a lot of quality but also the reference with your original material. Best way to edit IMHO is in DV quality. I'm working on a project with 90hrs of footage and captured it to a 2TB Disc (+/- 60% used space) in QT DVPAL codec. Just buy an external drive (they are not expensive anymore) for the required size i'd suggest you use something like this

 

[Nethfel]

I have to agree with xstep here - compressing dv quality footage down to fit on a dvd for convenience of storage space is not going to do you good in the long run.

assuming your Mac has a firewire port, as xstep suggested, I'd get a firewire chassis, but I'd probably get a 1tb drive so I'd have more working space as I'd set that drive to be my scratch drive then you wouldn't have to transfer anything too the Mac itself. This is how I transport my footage between my laptop and my desktop, as I have both editors set to point to that drive volume for my scratch location so I can just hook it up and go without transferring to another drive before editing. If your Mac has a firewire 800 port (most if not all new ones have this, older ones I can't guarantee, I don't know the specs on all of the older models) then I'd look for a chassis that has firewire 800 (1394b) - even better, a chassis that has FW800, FW400, usb and esata (I say esata, although it's not on any Macs right now, there is always a possibility that it may be in the future, and might as well have the connection if it won't add significant cost to the chassis - I the unit I had gotten had all ports on it) - the only negative with having both fw800 and fw400 ports is those chassis *usually* don't have a second fw800 (or second fw400) port on it which means that if you wanted to have multiple things on the fw bus, the drive would have to be last in the chain...

 

[Radical Posture]

Thanks guys. Yes, I have Firewire 800 and therefore have taken yo advice and bought a 1TB External Hard Drive. In hindsight, I don't know why I even listened to that videographer in the first place ... it's commonsense when it's pointed out - if you compress something, it loses quality ! Thanks again.