How can I shrink the size of a DVD without losing quality?

Hi everyone,

When I rip DVDs to ISOs, I have this giant 4.7GB file and I was wondering if I could shrink that to safe hard drive space, without losing quality.

Then I notice that whenever I DL BitTorrents of DVD rips or HDTV shows, they are all in AVI and have just the same great quality as my huge files, but they are only like 350-700MBs.

Could somebody please tell me a program that can convert DVD ISOs to this kind of AVI (and maybe back again)?

Thanks a lot

If there is such a thing, it would be at videohelp.com, but I doubt there is any way to go back and regain the quality. Shrinking of any kind, by definition, would have to remove something. To rebuild it would be impossible as the information is no longer there.

Thanks for the reply Well, I don't really need to go back and forth from AVI and DVD. I don't know why I said that b/c I can already burn DVDs from an AVI file... sorry about the confusion.

But anyway, I noticed that when I burn a DVD from an AVI, it bloats it to like 6 times as big, so I though that maybe there was a conversion program that would just shrink it to AVI, basically getting rid of the bloat without losing quality.

Woops, double post
Cuz of this this lol:
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The question to your answer, in simple terms is: You can't.

MPEG video, that which is used for standard video DVDs, is a lossy compression format, just as JPG is for images, MP3 is for audio, etc. Additional conversions to any other format to save space will only further degrade quality, even if it is what some might consider slight, which is the case any time you convert from one lossy format to another. There are lossless video formats, but they will take up enormous amounts of space in comparison to the original video.

Could you convert a 4GB DVD to, say, a 2GB Xvid (.avi) file and retain excellent quality? yes. But you'll be losing data and quality in the process, and if/when you want to burn the DVD as a standard DVD again, you'll have to AGAIN convert it back to MPEG2, which is what DVDs use. And doing so will mean you'll have twice gone through lossy compression conversions to get back to being a compliant DVD. Think of it as saving a JPG image or MP3 file over and over again, each time you do so you'll lower its quality by introducing more artifacts introduced by the compression, as well as getting further and further from the original with each conversion. If you don't mind losing quality in the process, you can use programs such as RatDVD or AVI to DVD, DVD to AVI programs to compress DVDs, you can look on Videohelp.com for lists and links to downloads to such programs.

Simply put, if you want to retain the quality of the original, you'll have to keep it as-is. You could mess around with using file compression such as Zip or Rar, but it will take a very long time to compress that much data and you'll yield probably 2% space savings at best, not worth the trouble.

Hmm thanks for the info. I will definitly check out that RatDVD program you suggested to shrink it to 50% etc.

But can I ask you a question? I ripped a DVD to an ISO image and ran it through DVD shink to get it down to 4.7G. (slight quality loss, but not noticable). Then i burned it to a DVD and took it to my friends house to watch (he has a big plasma screen as a computer monitor).

When I got there, he said he already had that movie... he downloaded it from BitTorrent (i know, he's BAD!). But I noticed that it was only a 700MB .avi file, yet it was the same quality as my pure format ripped version (at least it was not worse quality to MY eye).

So do you know what program those people on BitTorrent use to turn it into an .avi like that? I know it will lose some quality, but it essentially looks the same so it's not real important... that's why I keep the retail DVD in a safe place, so if I REALLY need the good quality version, I'll still have it.

I want to try to use RatDVD on my favorite movies, and compress my least favorite movies to like 700MB and such.

Thanks for your guys' help

i am using sony handy cam use mpeg2 .when ishoot it takes quite lot space.is there any way to save much space without losing quality

It all depends on what device you are going to play the file on. If you compress a 4.3gb movie to .avi format( 700mbs) it will play great on an IPOD but it will lose quality on a larger screen.