VBR vs. CBR

[gumpec]

I use Pinnacle Studio 9. Now there is possibility to choose VBR or CBR (variable or constant bit rate) Can somebody tell me which are advantages and disadvantages of this two possibilitis?

[guns1inger]

CBR uses the same bitrate (hence constant) throughout the encode, whether or not the video needs more or less.

VBR allocates bitrate around an average, using less in still or slow moving scenes, and more in action scenes.

A good encoder will use the same amount of space for a VBR encode as it will for a CBR encode when the VBR bitrate is the same as the CBR rate.

Bootom line, if you can allocate a high enough bitrate, CBR is fine. If you have a lower bitrate to work with (i.e runtime is approaching 75 minutes or higher), VBR is likely to give you a better result, especially if it is 2-pass. This quality increase comes at the price of speed, as a 2-pass VBR will take twice as long as a single pass VBR or CBR encode.