newbie: how to decide what bitrate to use

[blazo]

Hi!
I'm pretty new to MeGUI and x264 but have used XviD a lot (encoding my TV recs). I'm about to rebulid my DVD collection backup in h.264 format but I don't know how to decide what bitrate to use. Ok, there is bitrate calculator in MeGUI but I wan't a compromise between quality and filesize and I couldn't find a simple answer.
I will be encoding my DVDs in 960x540 (or at least 960xSomething) PAL system (yes, I will upsize H-res and keep V-res).
If I use loseless compression I get a perfect backup, but the size is too big.
My question therefore is: How to judge/estimate the needed bitrate for a near perfect DVD backup (960x540@25fps, x264)?
How can Enc help since the only option in Enc is XviD?
Thanks to all!

[Wishbringer]

--crf 18 in x264 should be nearly equal to q2 in xvid.
So why asking for bitrate?
Used bitrate depends on what source you have, crf tries to get a given quality.
All other is your personal decission. Some ppl say they see differences even with crf 15, other say crf 22 looks good enough.
So I only would go the bitrate path if I have limited space, say, i WANT 20 Episodes a 30 min on a Dvd5

[blazo]

So why asking for bitrate?

Well, I do need some info on resulting filesize. But anyhow, thanks for the tip. I never used crf on xvid since i wanted (as you pointed out) predictable filesize to fit certain number of files on a DVD.

[Wishbringer]

hm, how to say it in english...
Quality and bitrate have no direct relationship, except: bitrate increase while quality increase (in the SAME videoclip).
I encoded around 13 clips of 25 min anime ("Elfenlied") with crf 18 and got around 150 MB filesize for each clip.
Now you could pick up your bitrate-calculator and say, um, ok, a good bitrate for animes is xxxx kbits/sec. ---> and then you are wrong!!!
I encoded an 105 min anime clip ("Appleseed") again with crf 18 and got NOT around 630 MB expected filesize, i got around 1.1 GB!!!
Content was completely different: Handmade drawings agains computeranimated anime, much stillscenes against highmotion action.
And the same differences you would get with all your films you have and want to convert.
The more complex scenes are, the more motion, the more necessary details are in them the more bitrate you need.
Thats why I say: why asking for bitrate, better ask for quality (crf).
The only point I could give is: Use a compressibly test, encode around 3% of one movie with a given crf (there is an avisynth function which picks out each x frames of y), multiply by 33 and you get around your resulting filesize.
If too big or to small, adjust crf up or down. Up to the point where you see too much loss in quality or no more gain in it.
But as I wrote before, it's only for your current clip.