Compression w/ DVDShrink

[Insane666]

I just did 2 back-ups of Matrix Reloaded as a test. One, I just put the main movie and the english sound on it, then I compressed a little to fit it on the DVD. The second one I left everything on it, but compressed it about 40% to fit on the DVD. I then played both to compare and I couldn't really tell a difference in quality.
I'm just wondering what does compressing the original really do? Has anyone had an experience with compressing that the DVD was awful to watch?

[kheops]

with VirtualDub-MPEG2
http://fcchandler.home.comcast.net/
you could open directly your vob files
go to a frame you consider difficult to compress then same the frame (copy to clipboard)
do the same with the other set of files, you definitely should see some differences

+

[Kedirekin]

DVDShrink introduces two very noticeable forms of degradation at high compression, though in some movies the degradation is hardly noticeable.

The first is macroblock noise, especially noticeable in high motion scenes. Most people are familiar with this type of noise, so I won't describe it.

The seconds is a kind of phased smoothing that I haven't seen anywhere else. This is especially noticeable in movies with lots of grain (old 70's movies, for example). What happens is that the grain gradually fades away over about ½ seconds, then snaps back, fades and snaps back, over and over again. Note that this degradation isn't a smoothing out of fine detail; it doesn't appear to affect fine detail that's stationary. It only smooths out fine detail that moves around somewhat randomly, like noise (film grain being a good example).

If you have a low motion, clean movie, you may very well be able to compress it a great deal with DVDShrink and notice very little degradation. For example, I compressed DareDevil to about 60% (IIRC) and I thought the results were very good. [I know DareDevil is an action flick and you wouldn't normally consider it low motion, but low motion doesn't always mean the same in MPG as it does to you and I.]

However, when I tried 28 Days Later (which is intentionally grainy) at about the same compression level, it was pretty much unwatchable.

[mudda_t]

I've said it before, you can get away with a lot when viewing on standard tv's. If you switch to high def you will instantly notice a difference, it would look like you were watching a vcd. For fun I took reloaded down to 45%(w/deep analysis), from a 4.36gb backup, and the result (2.4gb total) looked like a vhs on standard.

[Insane666]

I do have a high def tv and player and with the full Reloaded disc compressed to fit onto one, it still looked perfect.

[mudda_t]

originally posted by Insane666
"I do have a high def tv and player and with the full Reloaded disc compressed to fit onto one, it still looked perfect."
You must be the exception!

[Kedirekin]

I also have an HDTV, though not a HD player. I wasn't aware such a thing existed - in fact I don't see how it can; DVDs are 720x480/576, not HD.

Anyway, the TV has several modes, the most detailed being vivid mode. A fair number of my Shrink backups look good even in vivid mode, but many do not. Then again, a lot of original DVDs don't look good in vivid mode either, so I don't know what conclusions to draw.

The DVDs (original or backup) that don't look good in vivid mode often look very good in movie mode or pro mode. I'm of the understanding that movie mode is the mode intended for DVD playback. Both modes soften the picture slightly - sharper than standard television (and much sharper than VCD), but softer than vivid mode. I'm perfectly happy to watch my backups in these softer modes.

Incidentally, cable TV is completely unwatchable in vivid mode. I typically choose one of the softer modes for watching TV too.

[Insane666]

I meant I have a progressive scan DVD player.