Constant bitrate film question

[Weirdo]

Hello.
I have this dvd. It's a 136min. PAL film, 4:3 letterboxed video with just a single AC3 2.0 track (192kbps) and a single subtitle stream. Total size: 6.48 GB (no menus or extras btw). Observing it with PowerDVD, it seems to have a pretty much constant bitrate at around 6400-7000 MBps, no matter what the scene is, whether a lengthy close-up, or an action scene (and there are not many of those -action scenes I mean- ).
So, I might guess it's encoded poorly, that's why it takes up 6.48 GB. My question is: will DVD-RB/CCE encode it in such a way that the result will be a 'smart' DVD-5 with nice VBR encoding, or a 'dumb' single-layer dvd with CBR, say, between 3900-4500?

Thanks

[Susana]

It'll be VBR. DVD-RB doesn't have CBR mode in its GUI.

[Weirdo]

Thanks. I asked because I seem to remember a while ago, encoding a similar film, and the result was an equally 'dumb' dvd, with similar "almost-CBR" results, with a bitrate lowered just enough to fit a dvd-5.

[jdobbs]

DVD-RB doesn't create CBR. It will, though, allocated bitrate across segments based upon the original bitrate, though.

If the original "varies between 6400-7000", that means the it is VBR also. Usually when you see that small a difference between the high and the low, the original source was recorded using an encode-as-you-go MPEG VBR engine (like what is used on a settop DVD Recorder). Those almost always use a lot more bitrate than is really needed.

[Weirdo]

Yes, "almost-CBR". Well, having sth. only between 6400-7000 pretty much makes the usefulness of VBR obsolete, right?
So, I am right to assume that the encoded dvd will be similar to the original's (unremarkable) use of bitrate allocation? Instead of sth.between 200-6800, it'll be, say, 3900-4500.
I mean, the numbers don't matter here, it's DVD-RB/CCE's way of doing this I am in doubt with.

[jdobbs]

No, that wouldn't be correct. When DVD-RB encodes the video it will vary as much as the encoder decides is needed -- you may have one section that is 300Kbs and another that is 7000Kbs. What I said was the the average bitrate for a segment (cell) would stay proportional to the original.

There's a big difference.

[blutach]

And, Weirdo, PowerDVD's OSD is not a good measure of actual BR. Use Bitrate Viewer (http://visualdomain.net/bitrate.htm) instead (altough calcs would show an avg BR of around 6400 for this movie).

Regards