[FFmpeg-user] Field Shift

[Steve Kelly]

Sometimes we have masters where there has been a previous transcode from a Lower to Upper field first codec (or vice versa) but the field order hasn't been changed correctly (usually when going from DV to ProRes, MJPEG, D10 etc).

Although this can only be confirmed visually on an interlaced monitor (juddering/flickering playback), fixing it is done in a NLE by dropping the file in, using the Field Shift option and re-exporting. Is this something that can be done with ffmpeg (and thus be automated) and if so how?

Thanks