Why output displays are distorted in running multiple videos?

I am testing deepstream-app with multiple video files.
The display of multiple video outputs are distorted. How can I keep the aspect ratio as input may be smaller, so that I can display with no distortion?

you can use nvmultistreamtiler element, with W 3 H 3

Where should I change?

Added
[multistreamtiler]
enable=1
rows=2
columns=3
width=1920
height=1080

inside deepstream_app_source1_peoplenet.txt file

But still the same.

Thanks I found sample in test3