How does exactly AMS sync a video stream with another stream of audio only ?

I have the following situation: 2 instances of FMLE on one machine and another machine with AMS Starter.

The instances of the FMLE are:

1. Video H.264 + audio MP3

2. Audio only MP3 - track 1

The application on AMS is a livepkgr/_definst_ and i am using HDS with a live event

I have an OSMF based player to consume the streams and to do audio switch using late binding audio.

When I consume the Video with the Default audio everything works just fine. The problem is that when I try to consume the Video with the other audio track, the audio tack has a 1 second delay compared to the video.

I have tried to fix this by changing the configurations on the FMLE, but it doesnt seem to work. So I really want to know how does exactly AMS syncronize differents streams, in this case a video stream with a different audio stream.