Editing FFmpeg Code

Hi, i have a working bash script code where it gets rtmpdump from a swf file which displays live events and pipes it to ffmpeg than ffmpeg sends it to nginx to publish them as HLS to end users. Sometimes rtmpdump fails or stops after a while and therefore ffmpeg stops, when this happens code is retrying to get rtmpdump and send it to ffmpeg for a set of times...

What i want to do is when rtmpdump fails ffmpeg should start sending a predefined loading video that i already created to nginx and resume sending rtmpdump data when it is available therefore creating a continuous stream to end user...