Question

I’m running a ffmpeg command to try to get the duration of a video file, the command is as follows…

system('ffmpeg -i C:\Users\example\Desktop\video9.mp4 -f ffmetadata')

When I run that line it outputs a lot of info to the rails console, including duration. But how would I capture that info so I can split it and grab the data I need? (I’m doing this inside a rails controller)

When I run something like this…

metadata = system('ffmpeg -i C:\Users\example\Desktop\video9.mp4 -f ffmetadata')
puts metadata

All it returns is false.

Answer 1

Use:

output = `ffmpeg -i C:\\Users\\example\\Desktop\\video9.mp4 -f ffmetadata`

The problem is that system doesn’t capture the output of the command being run. Instead, we use %x[...] or its equivalent using backticks, which captures the sub-shell’s STDOUT.

If you need more control, look at Open3.capture3.