Transform the field order of the input video.

It accepts one parameter which specifies the required field order that the input interlaced video will be transformed to. The parameter can assume one of the following values:

0 or bff

output bottom field first

1 or tff

output top field first

Default value is "tff".

Transformation is achieved by shifting the picture content up or down by one line, and filling the remaining line with appropriate picture content. This method is consistent with most broadcast field order converters.

If the input video is not flagged as being interlaced, or it is already flagged as being of the required output field order then this filter does not alter the incoming video.

This filter is very useful when converting to or from PAL DV material, which is bottom field first.

For example:

ffmpeg -i in.vob -vf "fieldorder=bff" out.dv