@ niku
avconv is broken for my distro and I don't have the time to look
into it right now. Could you please test if the same syntax works
for it (replacing 'ffmpeg' with 'avconv')? I think I'll add another
setting for that.
The options of ffmpeg and avconv are supposed to be exactly the same,
except that for avconv you need to follow the correct order strictly.
However, if I substitute `avconv' for `ffmpeg' in your command, avconv
extracts the beginning frame, not the frame around the 10th second,
which ffmpeg extracts.
ffmpeg -itsoffset -10 -i input.wmv -vframes 1 -y /tmp/ffmpeg-its.png
--> gets the frame at around 10s
avconv -itsoffset -10 -i input.wmv -vframes 1 -y /tmp/avconv-its.png
--> gets the first frame
However,
have you tried the option `-ss'? `-ss 10' substituted for
`-itsoffset -10', produces the desired result with both ffmpeg and
avconv. Further, on my system, it works much faster. With -itsoffset,
ffmpeg takes 1.80s to extract the frame at 10s. With -ss, ffmpeg takes
just 0.08s to extract the same frame! Also, the manpages of both
ffmpeg and avconv seem to suggest the use of -ss for extracting
images:
If you want to extract just a limited number of
frames, you can use the above command in combination
with the -vframes or -t option, or in combination with
-ss to start extracting from a certain point in time.
ffmpeg -ss 10 -i input.wmv -vframes 1 -y /tmp/ffmpeg-its.png
avconv -ss 10 -i input.wmv -vframes 1 -y /tmp/ffmpeg-its.png
--> both the commands get the frame at around 10s.
Note the `10', instead of the `-10' with -itsoffset.