VBR programmes pointless?

My brother informs me that all - or at least the bulk of - commercial DVDs are VBR, and that by backing up with Clone DVD which is a CBR program, it maintains the VBR in the same proportions as before the shrinking process.

He also says that his DVD player displays the bitrate and that it shows his backed up DVDs made with Clone DVD to be VBR.

This would make a VBR program like DVD Shrink pointless in terms of the VBR and that I am needlessly allowing the analysis and overall process to take 1.5-2 hrs needlessly when I could just go back to Clone DVD.

It doesn’t sound right to me, I’d say that commercial DVDs would be CBR at the highest level bitrate. That said, CDs are VBR…

Explanations welcomed!

I’m not sure that you’re using the terms CBR and VBR correctly, or at least in regards to the statement about CloneDVD. In order for CloneDVD’s output to be CBR, its output would have to have a constant bitrate. Reducing the bitrate proportionally to the original DVD is not the same thing as CBR output. In any event, I don’t know if CloneDVD incorporates this technique, but you can try to confirm this yourself using a program like Bitrate Viewer to view the bitrate distribution of both an original and compressed DVD.

Also, not all compression techniques are created equal. It’s up to your own eyes to decide whether or not the extra time is needed for any program to achieve its results. If you don’t see any difference between one output that took two hours to compress and one that took 30 min to compress, then by all means choose the faster method.

Almost all commercial DVDs are VBR. Using CBR would be a waste of bits on scenes that don’t require as many bits. It’s also unlikely that there are any commercial DVDs that actually maintain the maximum allowed bitrate on a DVD (10.08 Mbps) because that would only allow for about an hour of video.

Lastly, audio CDs are CBR, not VBR. You can read about it here.

If Shrink is taking more than half an hour to analyze, you’ve got one S-L-O-W machine or some other problem. VBR is a lot better in size / quality ratio and is almost always used on DVDs. In fact, CBR would be a waste of disk space in most cases.

I agree with Olyteddy!

Almost all commercial DVDs are encoded as variale bitrate. It is one of the features of MPEG2 encoding.

Most of the stuff taken by your handycam is CBR (about 6Mbps).

Within the domain transcoders like DVD Shrink and Clone DVD maintain the VBR aspects but tend to uniformly lower the BR across the movie to fit it into the available space.

Encoders, like CCE, HC, Procoder, start from scratch with the BR and quant parameters fed to them. This is why they are universally better than quick transcoding solutions.


So is there a difference between Clone DVD, given that one takes significantly longer than the other?

The thread that describes all of the programmes and their specs says that Clone DVD is CBR, too (although I forget where it is :s ).