Safe level of compression?

[Nilfennasion]

In the past few days, I have backed up a number of DVDs that were RSDL, using DVDShrink. In most cases, simply removing all the extra features and unnecessary subtitles or soundtracks was "enough" to keep the video from turning into a blocky mess. Some discs even come with so many additional features on them that the main film will fit into less than 4.35GB without any soundtracks or subtitles removed. Not that I don't remove them. Nearly all PAL discs come with so many subtitles and dubs that I'd never use, it's annoying. I've seen some discs where one can save over two gigabytes by removing dubs.

However, there are some cases where the discs are RSDL, and not just to fit unnecessary dubs or subtitles. Inevitably, one must recompress the video in order to make it fit on a 4.7GB disc. The problem, of course, is what threshhold one considers "safe" to compress the video at. While I've attained some pleasing results with as little as 63% of the data size of the original, what would really be considered the furthest one can compress the video data?

[sitlet]

on most movies that i use dvd shrink on, i dont compress more than 30% (70% left). on some really good movies that i really like, i will get rid of everything, and just do a movie only dvd, and try not to compress it at all if possible

[Nilfennasion]

That's about what I try to aim for myself (70%). Unfortunately, some discs, such as the Region 1 version of Spetters, just don't allow it. I'd use a program like IFOedit to split them up, but they made IFOedit very non-intuitive.

[Fluffbutt]

I was playing the other month with getting a dvd down to one or two mindvd (dvd format on cdr).

It took 4 shrinks of maximum allowed (about 58%) each time.
(I wish shrink would let me go right down to 20%!!)

The resulting 2 cdr's had video with 5.1 sound (full dvd size, dvd coding, not svcd or vcd) AND the quality was better than vcd, about the same as a good svcd.

I'd say it depends on the movie, but try it (use a cdrw - erase it if it don't work, burn to cdr if it does).