|
|
|
Theoretical question about UNcompressing
|
|
|
karen2003
Member
|
11. August 2004 @ 15:51 |
Link to this message
|
|
Hi everyone. As my pile of backed-up DVDs is now in the 100s, and more than half of those were originally DVD-9's, it got me thinking ... would it be theoretically possible to come up with an "un-Shrink" program in the future that will "uncompress" all those compressed DVDs for re-burning on dual-layer media? Or is it more likely that when dual-layer media is as cheap as single-layer is now (anyone want to speculate as to when that will be? ha!), I will have to re-back-up all my DVD-9 originals?
Again, this question is more theoretical than anything else. I guess the analogy I had in mind was the zipping and unzipping we can do with PKUNZIP or similar programs. Maybe that's a bad analogy -- I don't know enough about the technical aspects of this stuff.
Most of my DVDs have been compressed using Shrink. How about some of you computer engineers out there working on an unShrink program for our future needs? :-) Just a suggestion.
Any thoughts?
Karen H.--Dell Optiplex GX240, P4 1.50ghz, 256mb RAM (yeah, I need more), Windows XP Pro w/SP1, 80gb c: drive (replaced the 20gb c: that crashed), 126gb i: drive, 124gb j: drive, 500gb external hard drive partitioned into k: and l: drives, Sony DDU1621/C1 DVD-ROM to rip/encode, Sony DRX-530UL to burn, new Sony DRX-840U to burn DL discs ... need a new computer to go with it!!
|
|
Advertisement
|
|
|
|
Moderator
|
11. August 2004 @ 16:46 |
Link to this message
|
|
I would posit that "you can't make something out of nothing" would be appplicable here for the fact that you can't gain back quality that isn't there :)
My killer sig came courtesy of bb "El Jefe" mayo.
The Forum Rules You Agreed To! http://forums.afterdawn.com/thread_view.cfm/2487
"And there we saw the giants, and we were in our own sight as grasshoppers, and so we were in their sight" - Numbers 13:33 |
|
karen2003
Member
|
11. August 2004 @ 17:34 |
Link to this message
|
|
Ah, so the compression that Shrink does isn't like "zipping" a large data file to compress it? Guess that wasn't a good analogy. Can you explain the difference? I like to understand how these things work. Thanks!
Karen H.--Dell Optiplex GX240, P4 1.50ghz, 256mb RAM (yeah, I need more), Windows XP Pro w/SP1, 80gb c: drive (replaced the 20gb c: that crashed), 126gb i: drive, 124gb j: drive, 500gb external hard drive partitioned into k: and l: drives, Sony DDU1621/C1 DVD-ROM to rip/encode, Sony DRX-530UL to burn, new Sony DRX-840U to burn DL discs ... need a new computer to go with it!!
|
|
Veblin
Senior Member
|
11. August 2004 @ 18:07 |
Link to this message
|
|
In simplest terms compressing with a transcoder discards the least important video data while keeping the most important video data. Transcoders try to determine what is most important to keep to retain quality.
Any additional quality settings in a transcoder usually involve increasing the amount of time it takes to determine what is most important to keep. Of course any data that is discarded from the output is lost and can not be put back.
|
|
baabaa
AfterDawn Addict
|
11. August 2004 @ 22:14 |
Link to this message
|
|
Yes the term 'compression' is actually a little misleading BUT is exactly what happens.....
(Simple terms)
Repeated frames/empty spaces etc are removed (these areas take up bytes etc).....therefore the overall data is reduced - Hence Compressed.....
Therefore as veblin stated when removed = lost forever.....
Unless, you of course purchase the DL discs, and re-backup your originals - and in your case with >100, that would take some time especially as the DL media is only rated at 2.4x at the moment (30 mins to burn approx.)......
However I feel the compression resolution reduction imposed by todays software packages (just movie backup)is minimal, therefore if you have any 2 episode film type scenario - then you would be able to insert them on one DL Dvd.........
...............PIO is no go, DMA all the way...............
Beware of the Pixies - they move in over night and turn your life upside down
This message has been edited since posting. Last time this message was edited on 11. August 2004 @ 22:14
|
|
karen2003
Member
|
12. August 2004 @ 05:27 |
Link to this message
|
|
Thanks, guys. I didn't realize exactly what compression DID (i.e. remove frames). Now that I understand what it does, I see my original question was silly. :-) In a few years when DL media is cheaper maybe I'll just back up the originals that had a lot of compression (which I can check with my trusty spreadsheet).
Thanks again.
Karen H.--Dell Optiplex GX240, P4 1.50ghz, 256mb RAM (yeah, I need more), Windows XP Pro w/SP1, 80gb c: drive (replaced the 20gb c: that crashed), 126gb i: drive, 124gb j: drive, 500gb external hard drive partitioned into k: and l: drives, Sony DDU1621/C1 DVD-ROM to rip/encode, Sony DRX-530UL to burn, new Sony DRX-840U to burn DL discs ... need a new computer to go with it!!
|
|
Advertisement
|
|
|
|
ddlooping
Senior Member
|
12. August 2004 @ 06:47 |
Link to this message
|
Hi all. :)
karen2003, transcoders (including DVD Shrink) do not actualy remove frames.
Veblin's explanation is spot on. ;)
I'd just like to add..
Quote:
Any additional quality settings in a transcoder usually involve increasing the amount of time it takes to determine what is most important to keep.
...and/or how to best spread the compression between frames of different type.
This message has been edited since posting. Last time this message was edited on 12. August 2004 @ 06:49
|
|
