1 dvd backup solution: dvd shrink, mpeg2 or mpeg4?

[travisbicks]

I’ve recently started to back up my DVD collection and I’m wondering about the best method to use. My usual method is to use DVD shrink and - as I’m making back-ups to watch – to copy only the main movie. In many cases it is possible to do this without having to use the shrink function (transcoding I believe) of DVD shrink. However, with certain of my DVDs even the main movie alone requires some shrinking to fit on one DVD. For example, a main movie backup of my PAL DVD “One Flew Over The Cuckoos’ Nest” requires a 59.6% shrink.

My questions are:-
1) At what level of “shrinking”, using DVD shrink, will quality loss become noticeable?
2) In such cases (and excluding the option of splitting the film over two DVDs) what other option will give me better quality?
3) I have considered whether to encode using DVD Re-builder (and QuEnc) or to convert to a good quality Xvid using AutoGK (using the 75% default quality setting). As I’m not concerned with menus and extras on the DVD, AutoGK seems like the way to go. Am I right or will the quality of an mpeg2 encode be better than Xvid even in such cases as that of the DVD I mention above?
4) Is it true that the quality of Xvid playback is generally worse on Xvid capable standalones than on computer? I have a standalone DVD player that can handle Xvid files of over 2 gig (using the UDF DVD format) so files over this size are not a problem.

[manono]

Hello, and welcome to the forum-

1) No way to tell in advance. Plus, it partly depends on the quality and size of your display. Don't you think problems will be more obvious when viewing on a 110" screen as opposed to a 19" CRT TV set.
2) Use a real encoder, or an app which uses real encoders, such as DVD Rebuilder.
3) Interesting question, that. The XviD will be smaller, if that's a concern. If quality is the only consideration, I'd stick with the DVD, if for no other reason than the better matrices than what you'll get with AutoGK. In theory, MPEG-4 can be as good as MPEG-2, if you use a high enough bitrate and good high-bitrate matrices. Many standalones don't support XviDs with custom quant matrices, especially those using ESS based chipsets, and will stutter or freeze temporarily during complex scenes. Such encodes, therefore, aren't very practical for most standalones.
4) I haven't noticed that to be true. It's true that monitors have higher resolution, generally. And I've read of TV sets amplifying the macroblocks. But I just haven't found that to be true when watching on my Samsung DLP. Others might disagree. Since you already have a DVD/MPEG-4 player, it shouldn't be much trouble for you to find out for yourself. Same with question 3.

[travisbicks]

Thank you very much for your reply to my post

In your answer you say that, if quality is my goal, I’d probably be best to stick with mpeg-2, but that in theory mpeg-4 can be just as good. I must apologise for my ignorance but I’m not sure what you mean by “better matrices” with mpeg-2 – I’m a real newbie! Does this apply even when using the 75% target quality setting on AutoGK and when the mpeg-2 encode would be from a 7gig movie to a 4.7gig dvd? I am wondering whether that even if mpeg-2 encodes are generally better, they might still be bettered by Xvid when there is a 4.7gig limit. I have noticed that when I use the target quality setting on AutoGK it warns me that compatibility with standalones will be compromised; this makes sense to me now after what you say about standalones not supporting custom quant settings (not that I understand what these are). So I guess I’m asking whether obtaining better quality than mpeg-2 on a single 4.7 dvd is possible using AutoGK, but that you’d advise against it due to possible compatibility problems at high quality settings; or whether encoding such a high quality mpeg-4 would require the use of programs other than AutoGK and a high level of technical competence.

I should really run some subjective tests myself but the television where I’m currently living is awful. I plan to buy a better one soon :D
Thanks again

[manono]

Hi-

Sorry for the late reply. Most XviD and DivX encodes are made for only a CD or 2. If they're made for a standalone, then there are usually restrictions on the max bitrates and the length of time high bitrates can run before stuttering and freezing occurs, and often restrictions on the matrices that can be used without getting a garbled picture. Because of these factors, the 2 basic matrices in use for both XviD and DivX are the H.263 and the MPEG matrices. The 2 default custom matrices used by AutoGK are of similar quality. A matrix removes detail to make the video more compressible. A low bitrate matrix, such as H.263, removes a lot of detail. A high bitrate matrix, such as the ones used by Hollywood movie DVDs, removes mostly high frequency detail, detail that won't be noticed that it's missing. Because most AVIs are for relatively small sizes, they remove a lot of detail, and these AVIs won't usually be confused with the original DVD. If you don't care about standalone compatability, and don't mind getting up in size to half a DVDR or even greater, then you can use quantization matrices that will give results as good (or better) as reencoding the original DVD movie to MPEG-2 yourself.

Matrix info with links for the technical minded:

http://ronald.vslcatena.nl/docs/xvidfaq.html#C3a

Matrix info in layman's terms:

http://forum.doom9.org/showthread.php?p=318172&highlight=matrix#post318172

If you wish to experiment, a number of matrices are included with Koepi's XviD codec. More are included with LiGH's nice little app:

http://forum.doom9.org/showthread.php?t=73666&highlight=CQME

Get the qmatrix.zip file, which includes many matrices.

So I guess I’m asking whether obtaining better quality than mpeg-2 on a single 4.7 dvd is possible using AutoGK,

Good quality, yes, but better than reencoding to MPEG-2 yourself? Not if you know what you're doing.

...or whether encoding such a high quality mpeg-4 would require the use of programs other than AutoGK and a high level of technical competence.

Other programs, yes. High level of technical competence, no. Just read the rest of that XviD FAQ, and use a nice high bitrate matrix, such as maybe Didee's 6 of 9, or the Fox Home Entertainment matrix (commonly used on retail DVDs), and you might be amazed.

[travisbicks]

Thank you so much for taking the time and trouble to answer my questions! After what you’ve told me, and in the interests of compatibility with standalones, I think I’ll go for the DVD Rebuilder (and QuEnc) option to back-up my movies that are over 4.7gig. However, you’ve given me a lot to read about and I’ll try out the custom quant matrices with Xvid to see what the results are like. I had no idea that DVD backup could be so complicated and so interesting.

If I get the high quality Xvids right I might even try using the Matroska container in order to be able to use chapters and menus, and sod compatibility with standalones. I suppose I could use the TV out from a laptop to play these DVDs on TV, although it’s hardly the most convenient method; for example, I’d have to take either the original DVD or my laptop with me if I wanted to watch a DVD at a friend’s, not to mention the noise my laptop makes!

Anyway, thanks again for the info! :goodpost: :thanks: