VBR or CBR that is the question !!!!!

[tricktum]

What are the guide lines when selecting either CBR or VBR when converting a movie from avi to Mpeg using TEMPGEnc.
I know its a bit late in the day for me and I must have been very lucky in the past because all the movies I have done seem to have come out ok.
However a recent hick up with my puter and a complete format, things don't seem to be going as well as they did before.

Using GSpot - I have noticed that the avi format tells me either CBR or VBR.
Should I keep in line with what the original avi format was created with.

Does it make much difference ????

Many Thanks.

[Vejita-sama]

Basically CBR (constant bitrate) uses the same bitrate through out the entire encode. While VBR (variable bitrates) raises or lowers the bitrate during the encode. For a VBR encode you enter three values:

min - the minimum bitrate the encode will drop to
average - the desired average bitrate
max - the max allowed bitrate during the encode

During a VBR encode the bitrate will be decreased during low motion scences (but not below the min value) and raised during high motion scences (but not above the max values). It will be raised/lowed so that it works out to the average value. Hence you can still predict file size (ave bitrate x runtime).

Max = DVD player max 9800
ave = from bitrate calculator
min = 300~500

you want to set the min REALLY low to give the encoder more room to play with. The encode will most likely never drop that low (remember it has to average out) but it does allow the encoder to go to the max bitrate during really high motion scences should the need arise.

For encodes >6000kbit/s (some would set the number lower) just use CBR as it's much faster. If that is if your encoding at near max bitrate anyway there's no need for a VBR encode.

That is a 300, 8000, 9800 encode isn't going to look much different (esp at 1/2 D1) than a CBR 8000 encode.

[Ejoc]

VBR or CBR that is the question !!!!!

VBR if you arent going to use MAX bitrate in CBR

300min/2000avg/2520maxVBR is better looking then 2000CBR. that is the answer!!!!!!! :P

[tricktum]

OK - Think I have got that.
will give it a shot.
Thanks very much...