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Justin Pearson

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ffmpeg - how to tell if video is interlaced

ffmpeg video 
ffmpeg -filter:v idet -frames:v 500 -an -f rawvideo -y /dev/null -i input.mkv

Example output:

[Parsed_idet_0 @ ...] Repeated Fields: Neither: 480 Top: 15 Bottom: 5
[Parsed_idet_0 @ ...] Single frame detection: TFF: 20 BFF: 10 Progressive: 470 Undetermined: 0

Key fields:

  • TFF / BFF: Top-/Bottom-field first = interlaced
  • Progressive: Most frames are not interlaced
  • Undetermined: Couldn’t detect

How to interpret:

  • If TFF + BFF > 0 → your video is interlaced
  • If Progressive ≈ total frames → video is progressive