Detecting interlaced video with ffmpeg

• Extracting more frames (raising -frames:v) improves the accuracy of detection.
• High numbers of TFF and BFF mean a video is very likely interlaced.
• TFF means interlaced with "top" frames and BFF means interlaced with "bottom" frames.

Interlaced content is relatively rare to encounter in the wild now.

ffmpeg -filter:v idet \
    -frames:v 100 \
    -an \
    -f rawvideo -y /dev/null \
    -i ~/Downloads/some_interlaced_video.mkv
# Example output (this is interlaced, TFF style)
# [Parsed_idet_0 @ 0x1ccf7c0] Single frame detection: TFF:167 BFF:0 Progressive:1 Undetermined:0
# [Parsed_idet_0 @ 0x1ccf7c0] Multi frame detection: TFF:168 BFF:0 Progressive:0