Install librtmp-dev by entering the following commands in the terminal:
sudo apt update sudo apt install librtmp-dev
Description:
toolkit for RTMP streams (development files)
A small dumper for media content streamed over the RTMP protocol (like BBC's iPlayer high quality streams). Supplying an RTMP URL will result in a dumped flv file, which can be played/transcoded with standard tools. . This package contains the development libraries, header files needed by programs that want to compile with librtmp.
Homepage: http://rtmpdump.mplayerhq.hu/
Version: 2.4+20151223.gitfa8646d.1-1
Section: libdevel