Video file thumbnail

[jum]

When I produce a MP4 video file in X4 it shows a thumbnail in the video file.
I cannot figure out where this image comes from. It seems sometime to be the first video image from all tracks, but sometimes it is just the upper video track and sometimes it is a picture from a later point of the video.
How does it work? And how can I control which image is used?

[BrianCee]

Do you mean the thumbnail which appears in the library pane - mine always seems to show the first frame of the video, I've never noticed it showing anything else, or do you mean the thumbnail in the DVD menu ? or something else ?

[jum]

I am talking about the thumbnail which the file browser shows for the MP4 file producen by X4.
Often it shows the first aggregated picture from all tracks, but sometimes it shows only what is in the first track and sometimes a picture later in the video.

[Ron P.]

If it's the Browser, this is an operating system thing. VS uses the windows explorer browser if you will. VS has no control in how thumbnails are displayed in a windows explorer window. Screenshot is of this browser window in Vista though.