How to determine if a mkv / avi / whatever file is constant or avg bitrate?

[smackyourfupa]

I use MediaInfo to check video files properties but don't see if any of the video files are constant/average bitrate. Is there a way to tell? Thanks.

[davexnet]

I'm not sure if there is an absolute way to tell. You could use the bitrate viewer, from the tools section at this site.
If there is a big swing in the graph, it's probably 2-pass.
Here are two images. I encoded them both at 780 kbps, 1-pass and 2-pass.

[Computer Nerd Kev]

Some videos in MediaInfo show whether they are constant or variable bitrate while others don't, I assume that this is due to variance between encoders as to whether they put this information in the video header or not.

As far as I'm aware, all video encoders regard constant bitrate as an aim but not a true limit, thus they never actually give a constant bitrate but rather minimise variation as much as possible.

In davexnet's 1-pass video you can see that it hovers around the same mark while davexnet's 2-pass example shows the rises and falls in a variable bitrate video where the aim is for it to have an average bitrate across the whole video.

To my knowledge, a single pass video may be either constant or variable bitrate, however a two pass encode attempts to further adapt the bitrate to the video content which increases the variance in bitrate.

[smackyourfupa]

thanks for the info