[FFmpeg-user] Interlaced frames not recognized as such

Carl Eugen Hoyos cehoyos at ag.or.at
Fri Apr 25 17:27:10 CEST 2014

Robert Krüger <krueger <at> lesspain.de> writes:

> Summary: Frames from an interlaced file created using ffmpeg's
> tinterlace and fieldorder filters are not recognized as interlaced by
> ffmpeg.

Did you test the idet filter?
Only this filter (of FFmpeg's features) can tell you if the *content* 
of a video stream is interlaced or progressive (the filter can not 
yet identify telecined content, it is probably not very difficult to 
add this).

> Now I wonder if I used the wrong CL for creating the file or
> if interlaced detection fails in this case.

> I created an interlaced file by this command line (full output included):

Just to clarify:
You created a progressive MPEG-2 stream showing interlaced frames.

> ffmpeg -i color_frames_png_1080_50p.mov -vf
> "tinterlace=interleave_top,fieldorder=tff" -vcodec mpeg2video -q 1
> -pix_fmt yuv422p -r 25 -y color_frames_mpeg2_1080_50i_tff_3f.mov

There is an option to create an interlaced MPEG-2 stream but you did 
not use it (-ilme -flags +ildct), so a progressive stream was created...

Old MEncoder documentation suggests never to use -qscale 1 but 
-qscale 2.

> interlaced_frame=0

which is reported by ffprobe.

Note that ffprobe will report "interlaced_frame" for a (sd) dvb recording 
no matter how progressive the content is.
(Our tv providers always flag "interlaced")

> The file is reported as interlaced by ffmbc, mediainfo if anyone 
> cares to know.

Sounds like a bug to me.

Carl Eugen

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