How to pad video with black frames to a given length with FFmpeg?

Question

I am aware that tpad filter has the stop_duration parameter that adds frames to the end of video. How do I make sure that the resulting video is say 5 seconds in length when the input length is unknown (but less than 5s)?

Answer 1

添加修剪过滤器以限制总持续时间，例如

ffmpeg -i in -vf tpad=stop=-1,trim=end=5 out