ffmpeg fails with: Unable to find a suitable outpu

Question

I am trying to record my desktop and save it as videos but ffmpeg fails.

Here is the terminal output:

$ ffmpeg -f alsa -i pulse -r 30 -s 1366x768 -f x11grab -i :0.0 -vcodec libx264 - preset ultrafast -crf 0 -y screencast.mp4
...
Unable to find a suitable output format for 'pipe:'

Answer 1

Use -preset, not - preset (notice the space). Your typo is being interpreted as a piped output.

For users who get the same error, but actually want to pipe, you have to tell ffmpeg what format the pipe should be by using the format output option, such as -f mpegts. You can see a list of formats with ffmpeg -formats (not all can be used for a pipe).