Video storage, compression, quality and efficiency

[trev_r]

I'm pleased to say I have found some answers reading through others' problems. I haven't been able to find this one and just feel like asking, so any help would be appreciated.
I would like to store (long term in as high a quality as practical) some video footage. My prefered way so far is as an MPEG on a data disc.
I would also like to burn compilations for DVD player use now. These generally go over an hour so require some compression.
The procedure at the moment involves rendering movies in HQ from DV recordings then compressing to a lesser quality to fit on a DVD, this takes a lot of time. How much quality loss is involved in re-rendering (a bit like asking, how long is a piece of string). Would it be better and more efficient to render the originals to something less than HQ to start with and store and use that?
PS. I didn't want to bore you with system details etc but it's adequate but has to work hard.
Thanks

[DVDDoug]

I would like to store (long term in as high a quality as practical) some video footage. My prefered way so far is as an MPEG on a data disc.

The only way to preserve ALL of the original quality is to keep the video in it's original format. If its in DV format, you can keep the original tape, or split-up the AVI/DV file into 20 minute segments, and save it to multiple DVDs.

That might be important if you plan on re-editing it in the future. You wouldn't want your new edit to be degraded by a 2nd MPEG encode, and if you are using HD-DVD when that time comes, you'll need the highest quality source possible.

(Personally, I usually assume that the DVD is "good enough". And since I'm not planning on re-editing it, I just make a back-up of the DVD.)

How much quality loss is involved in re-rendering (a bit like asking, how long is a piece of string).

I really don't know, I've never done any scientific experiments. But, I think the situation is worse when you're working at low bitrates. (I'll bet that if you re-render from 4500kbps to 4000kbps, the result will be noticably worse than rendering once to 4000.)

How does it look to you? How picky are you about video quality? Do you have a plasma TV?

I assume that most codecs have to uncompress the frames, and then start-over with a new lossy compression operation. If that's true, you will get some quality loss even if you re-render to the exact same bitrate! (I've noticed a loss of qality when I've made a transition between two MPEGs, or when I've applied a filter or effect to an MPEG.)

If you are going to make two MPEGs, it really shouldn't take any longer to make both MPEGs from your original DV file.

I have a feeling that DVDshrink can add compression without a full decode/re-code cycle.... I'm not sure, but it does a good job!

[ekholbrook]

One of the best investments I made recently was to purchase a removable dual layer DVD Burner/DV/Video Capture drive that needs no computer intervention (but can be used w/ a computer when you want it to).

Cost about $250.

What it allows me to do is burn RIGHT from a DV Camcorder (or other lesser quality video source) to a DVD (dual or single layer) in HQ mode (varying modes depending on what you want to do. No Computer involved.

Captures DV input, S-Video, Composite, and as mentioned, can function without a computer hooked up, then, when done, plugin the computer and away you go. It burns to DVD in realtime. Totally Awesome.

That basically gives me the original footage, stored away nice and clean on a DVD. I can then use Uleads own DVD creator to do a nice conversion back to MPG when the time is right (takes about 5 minutes to convert 2 hours of video and is not a stated feature...the videos get stored in a "capture" folder as 'capture0001.mpg capture0002.mpg, etc..). These files are automatically created when you do an "import DVD video". [I spent 3 weeks looking for a good DVD-MPG converted before I realized this software already did it, and does it better, and it's not even in the manual!]

I use those mpg's to then go back and do my editing when necesary. And I leave the DVD alone.

With a dual layer DVD you should get pretty decent amount of time.. guestimating 4 hours(?) of HQ quality

[PeterMilliken]

I would like to store (long term in as high a quality as practical) some video footage. My prefered way so far is as an MPEG on a data disc.

The only way to preserve ALL of the original quality is to keep the video in it's original format. If its in DV format, you can keep the original tape, or split-up the AVI/DV file into 20 minute segments, and save it to multiple DVDs.

You don't need to split the AVI into segments - DVDDoug does this because he does not use or does not have an application that allows large files to span multiple DVDs.

If you keep all of the video files you wish to archive in their own separate hard disk partition then you can use a disk imaging program such as Image for Windows (shareware, so you can try before you buy) to archive the entire partition contents i.e. it doesn't care how many files or how big they are, across multiple DVDs. Image for Windows is inexpensive and not only allows easy archival of your video information but can be used to snapshot image your C: drive to DVDs i.e. you can restore your current computer setup to that snapshot image at any time in the future - as opposed to re-imaging your hard drive and then reload each application (and driver) one after another etc etc. I do this on a regular basis when my C: drive just becomes too "bloated" and I want to return it to it's original lean and mean appearance (remember to backup any user data before restoring though!!!!).

I would recommend keeping the original tape (which is prone to recovery failure because (a) it is magnetic media and the magnetic information can 'drift' with time, and (b) in the case of my Panasonic 3 CCD camera manual at least (and this is quite possibly true of other cameras!) they DO NOT GUARANTEE that you will get the same colour reproduction when reading the tape back on other devices! i.e. if you depend on tape as archive and your current camera goes belly up then you may never be able to accurately retrieve the tape information!

So if you use a disk image program such as Image for Windows and keep the original tape then you have two sources of archive.

Please note that when using any archival mechanism you should regularly "test" the integrity of the archive media i.e. in the case of DVDs maybe do a read of them once a year or something like that - similarly with the tape, although it could be argued that this exposes the tape to unnecessary wear - which may damage the archived information

But in my experience as a computer programmer, people who do not test the integrity of their archives sometimes get nasty surprises when they go to restore their archived material and find they have either been incorrectly performing the archive i.e. information is just not there! or the archive media has deteriated with time

Hope this helps,
Peter

P.S. This is all written up in the "DownUnder Perspective" (In Recommended Procedure Post) under "Archival Mechanisms" - http://www.seedwiki.com/wiki/video_stud ... pid=194534