[FFmpeg-user] Possible to seek by percentage?

[Eugene Gekhter]

Scenario:
Unknown video length uploaded by user.
Need to -ss to halfway in the video.
I know I could first run ffprobe/ffmpeg and parse the output to get
duration, then store the duration in seconds divide by two and round, store
that in a variable and pass that to the -ss command...

Question: is there an API built in which eliminates the need for the above
steps and we can simply do something like -ss 50% ( I know this returns an
invalid duration).

Thanks,