I was reading about the -re option in ffmpeg .
What they have mentioned is
From the docs
-re (input)Read input at the native frame rate. Mainly used to simulate a grab device, or live input stream (e.g. when reading from a file). Should not be used with actual grab devices or live input streams (where it can cause packet loss). By default ffmpeg attempts to read the input(s) as fast as possible. This option will slow down the reading of the input(s) to the native frame rate of the input(s). It is useful for real-time output (e.g. live streaming).
My doubt is basically the part of the above description that I highlighted. It is suggested to not use the option during live input streams but in the end, it is suggested to use it in real-time output.
Considering a situation where both the input and output are in rtmp format, should I use it or not?
Don't use it. It's useful for real-time output when ffmpeg is able to process a source at a speed faster than real-time. In that scenario, ffmpeg may send output at that faster rate and the receiver may not be able to or want to buffer and queue its input.