Cbr contra Vbr ?

[pellets]

Hello

I just wondered....
If one have a movie whose bitrate one want to be 8000, would it be best to choose to set the Constant Bitrate to 8000, or the vbr to 8000 ?

Whats the difference between these two methods?
Whats the advantage using cbr?
Whats the disadvantage using cbr ?

And, one last question...
Whats the easiest and best program to use, if i want to set the bitrate of one or more m2v-files in a movie, to a certain bitrate?

Appreciate any help.

Best regards:

[edDV]

Quick answer. DVD players max out close to 9Mb/s but you need to leave room for audio as well.

CBR is constant bitrate, one pass and predictable
VBR distributes bitrate by motion. You spec a max, ave and min bitrate. 8000 VBR ave with 9000 max might create overshoots that glitch some DVD players. Safer to use CBR when pushing the upper limit.

[pellets]

Hello

Ok, thanx for the answer.

Regards:

[ZippyP.]

VBR is most useful in getting the best quality when space (ie filesize) is a concern and your bitrate is limited. If you're approaching the higher bitrate limit then you won't see much improvement using VBR anyway.

[pellets]

Thanx for the info.

Perhaps you could answer me on this also:
What is the connectino between the framerate and the bitrate?
Is it like if the bitrate increases the framerate increases also, and vice versa?

Appreciate any answer.

Best regards:

[guns1inger]

No connection at all. Framerate is determined by format. Bitrate is a function of data transfer. The more data, the higher the quality (all else being equal). The DVD spec is designed to ensure that all compliant hardware can transfer the maximum allowed amount of data without compromising framerate or quality.

You may find that on an underspec'd PC you get less than the full framerate because it cannot keep up with the data transfer rate required. That is an issue of raw grunt, not framerate itself.

[jimmalenko]

If you increase your frame rate, then you need to increase your bitrate in order to retain a similar level of quality. But this has to actually be done by you.

Here's a few threads that discuss VBR and CBR in reasonable detail (found them with a forum search) :

https://www.videohelp.com/forum/viewtopic.php?t=248179
https://www.videohelp.com/forum/archive/t243196.html
https://www.videohelp.com/forum/archive/t242515.html
https://www.videohelp.com/forum/archive/t241977.html
https://www.videohelp.com/forum/viewtopic.php?t=97391
https://www.videohelp.com/forum/archive/t249873.html
https://www.videohelp.com/forum/archive/t245167.html
https://www.videohelp.com/forum/archive/t274906.html
https://www.videohelp.com/forum/archive/t250719.html