[FFmpeg-user] Stream microphone to speakers

[Vi Rak]

Dear gentle experts,

I'm working on the Karaoke project for both Android and iOS where a user
could record their performances (their video and vocal) and I use FFmpeg
for mixing music with their recordings. Anyway, I wish I could route/pipe
user vocal at realtime (capture thru device microphone) to an output device
(speaker) so the user could hear their voice at realtime applied with some
level of echo (to produce an effect as if we were in classic karaoke room).
Over weeks I have been struggling with searching the ways to implement that
based on FFmpeg, but no luck. Please kindly help.

Many thanks in advance.
Virak