Is there any way to re-encode a movie witout losing quality?

[k@y@]

Hi to all.

I have some films coded with xvid and i need to re-encode this films some reasons. (Truncated files, cbr-vbr sound problems and my divx player's problem: It can not play qpel movies)

I did re-encode a few times that movies but, at the end, i have a low quality movie or same quality but double size movie.

Especially, i want qpel films to be just mpeg4. Not bvop, qpel or something like that options. Whenever i try re-encode without that options, at last, low quality wity same fps and same size (approximately) or same quality, same fps but double or triple size...

How can i solve this problem or can i solve this?

If you want, i can post some pictures about this situation...

[The Geek]

You can't.

Re-encoding always means quality loss.

The Geek

[Leo 69]

Hi there ! You know a long time ago I had Lord of the Rings on 2Cds
and for my personal reason I reencoded it onto 1cd.I just lowered res a bit and added a couple of filters.Well I was surprised to see pretty
nice quality after reencoding...But anyway there IS quality loss but not that terrible you know..BTW I used DivX 3.11 :D With Xvid the result would be better,of course.Besides you are trying to get the same size and I decreased the size a lot.So just give it a try mate :)
It's really worth a try!

[Teegedeck]

Originally posted by k@y@
Hi to all.

I have some films coded with xvid and i need to re-encode this films some reasons. (Truncated files, cbr-vbr sound problems and my divx player's problem: It can not play qpel movies)

I did re-encode a few times that movies but, at the end, i have a low quality movie or same quality but double size movie.

Especially, i want qpel films to be just mpeg4. Not bvop, qpel or something like that options. Whenever i try re-encode without that options, at last, loose quality wity same fps and same size (approximately) or same quality, same fps but double or triple size...

How can i solve this problem or can i solve this?

If you want, i can post some pictures about this situation...

Theoretically reencoding always means a quality-loss. In practice, you can reach a transparent encode if your original has a very high quality and you encode at very high quality. Ideally a visible loss would not occur in the second generation of transparent encoding already.

But I don't think this is the kind of encodes you ask about here, because few people do transparent encodes.

So your chances of a still tolerable level of quality degradation depend first of all on the quality of your original source. If you reencode something of mediocre quality you'll very probably be able to see a quality-loss. You'll have to use postprocessing to get rid of existing artefacts because otherwise these artefacts would be stronger in the reencode.

Not using advanced MPEG4 features will increase the filesize of your reencode considerably and also decrease quality, as far as not using quarterpel is involved:

If you don't use quarterpel although the original does use quarterpel you will use sharpness. You could try to make it up by using a sharpening filter but this would increase the filesize of your reencode even more.

And by the way, quarterpel, b-frames etc ARE MPEG4, so not using them isn't a 'pure' MPEG4 but a 'poor' MPEG4.

It would seem a good idea to crop your resolution in order not to align the original macroblocks with the new ones. Be careful to retain at least a resolution that can be divided by 8; ideally one that can be divided by 16.