PreviewFrameOffset
PreviewFrameOffset specifies the position in the video, where thumbnail and preview images are created from.

0: FirstFrameProxy (default)
Reads 256 KB from the file copies it to the temp folder and gets the first frame

1: FirstFrameHiRes
Reads 1 MB + from the file copies it to the temp folder and gets the first frame

2: Byte1MB
Reads 1 MB from the file and delivers the last valid frame of the 1 MB part of the clip

3: 20 Second
if the duration is less than 3 seconds, the first frame is returned,
if the duration of the file is less than 40s the frame at duration/2 is returned. If the duration is greater than 40s. Frame from position 20s is returned

4: Mid of video
the frame of duration/2 is returned

Lower numbers usually results in faster creation of thumbnails and preview images due to fewer bytes are transferred to the harddrive and fewer seeks are done on the media.

In case of a camera image contains thumbnails (e.g. P2: CONTENTS\ICON) the thumbnails of the camera are used and this parameter has no effect.
Possible values: 0, 1, 2, 3, 4
Default value: 0