point of diminishing returns: -> 90% ?

[cfp999]

I have done a couple of movies with DVD Rebuilder now, and I am very happy with the result. At 68% I think the quality is clearly better with DVD Rebuilder compared with DVD Shrink. Details are sharper and there is less noise in blurred backgrounds etc. My question is: can it hurt to re-encode at only say 90-95%? Is it possible that re-encoding could actually make it worse as compared to transcoding when compression is very very light?

[TheSeeker]

Its absolutely possible that the result could be a little worse with a total re encode at high bitrates like that. Most people in those instances use shrink or IC i think. I know I do.

[nburles]

Absolutely anything is possible :)

I see no reason why a re-encode should be worse than a transcode... but its probably unlikely you'd be able to tell the difference - and a transcoder may be able to reduce the bitrate of the menu, thereby keeping the movie almost 100% (which could look better).

So time-wise it's obviously a lot quicker using a transcoder, and I doubt there'd be a noticable difference in most cases.

NBurles

[jdobbs]

The important question is "90% of what?" -- if the original is barely on the edge of the quality line, a transcode can make it look terrible while an encode might show very little loss.

On the other hand -- if the original had a very high bitrate (and resulting lower compression) you can sometimes transcode with almost no noticable change. But be warned... this is very, very rare when converting from DVD-9 to DVD-5. In most cases reencoding will result in better final quality.

When in doubt, and you're not in a hurry, just reencode it.

[lamster]

What I would recommend doing (when you have some time) is taking such a movie and trying it both ways, then compare the original and the 2 backups, and see which works best for you on your equipment.

What I generally do if the movie "almost fits" is to run DVD-Shrink, select no compression for the main movie, and let it compress everything else as much as necessary. (If there's previews, I might also give those maximal compression in order to leave more room for "extras".)