ffmpeg detect interlacing

ffmpeg-interlace-test.sh

#!/bin/bash

# for a blogpost on this, check: http://www.aktau.be/2013/09/22/detecting-interlaced-video-with-ffmpeg/

# detect interlacing with the ffmpeg "idet" filter, the longer
# you let this run, the better, though it's never 100% accurate

# flags:
# -an            = discard audio, we don't need it
# -f rawvideo    = output raw video
# -y NUL         = discard the output (one can use /dev/null on UNIX operating systems, NUL works for all)
# -i ...         = the input file to check
# -frames:v 100  = extract the first 100 frames
# -filter:v idet = insert the "idet" filter, which will output whether it has detected interlaced frame

ffmpeg -filter:v idet -frames:v 100 -an -f rawvideo -y NUL -i ~/Downloads/PSY\ -\ Gangnam\ Style\ -\ iHeartRadio\ Music\ Festival\ 2012\ 1080i60\ H.264\ 35Mbps.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 Undetermined:0

ffmpeg -filter:v idet -frames:v 100 -an -f rawvideo -y NUL -i ~/Downloads/startrek1.mov
# Example output (this is not interlaced):
# [Parsed_idet_0 @ 0x1bcf720] Single frame detection: TFF:0 BFF:0 Progressive:564 Undetermined:84
# [Parsed_idet_0 @ 0x1bcf720] Multi frame detection: TFF:0 BFF:0 Progressive:623 Undetermined:25

# scan all files, uses GNU parallel
locate -0 '.mov' | parallel -0 ./ffmpeg -filter:v idet -frames:v 100 -an -f rawvideo -y NUL -i {} 2>&1 | egrep 'idet|Input'

Thanks all. I've updated the gist.