[Ffmpeg-devel] interlace, duration and vhooks

[Marcus Engene]

Running
 ffmpeg -v 2 -i file1
I get one duration of a file but if I convert the file to
another format
 ffmpeg -v 2 -i file2
the duration seems not always to be correct?

I had one thing in mind to get around this; I convert files
to another format and what if I use a vhook that just counts
the frames and on exit writes # of frames to a file? Eg:
 ffmpeg -i infile -vhook '/.../counthook.so -f /.../apa.txt' outfile

If this is alright, I will get a problem with interlace vs progressive.
The fps output says the number of frames, not fields, and as it looks
now, vhooks cannot say if they're processing a full frame or an
interlaced frame (field?)?

Would it be a lot of work to add in the probe output from ffmpeg that
a file is interlaced?

Thanks!
Marcus