cbr or vbr? steaming or progressive download?

Hi All,

I need to compress a video into wmv format for online delivery but am confused as to whether it should be compressed using cbr or vbr.

3 questions:

(1)
As I understand it, cbr should be used for real-time streaming while vbr can be used for downloadable files. How about online delivery via progressive downloads? Should they be compressed using cbr or vbr?

(2)
In any case, I'm not really too sure as to whether what I need is a file compatible for streaming or for progressive download. What I have been told is that users on a website will link a link to access the video, which will then be played through windows media player.

With this info, should I then compress using cbr or vbr?

(3)
I would much rather compress using vbr since my attempts at cbr encoding have produced jerky motion in certain sequences. However, I don't want to hand in a vbr that would be ultimately unusable.

The client has not stated categorically that cbr compression is needed. But that is only because they are not very sure of what they need.

What can I ask the client that will help me determine whether what they need is a streaming file or a progressive download file?

Any advice and clarification will be much appreciated. Thanks in advance!