How to determine webm duration using ffprobe

Question

My goal is simple , I have several webm files need to be concated, but first I need to determine their durations.

It seems webm file are played as streams, so there

Answer 1

I faced the same issue with some files that does not contain the Duration nor Bitrate on it and found the following solution:

1- Repackage the files with: (Note that this won't transcode the files, just will copy them)

ffmpeg -i source.webm -vcodec copy -acodec copy new_source.webm

2- Take the duration from the new copied file:

ffprobe new_source.webm | grep Duration