To do live streaming with GoPro, you need to
- set the On Screen Display to Off
On Screen Display adds to the hdmi field an overlay showing different settings, such as battery, resolution... If it's not remove, then it will appear on the stitched video!
- Touch display should be power off for GoPro Hero 4 Silver
- Auto power off should be disabled
- Although not necessary, I usually turn off the beeps. When you need to change settings on 6 differents cameras with sounds off, people around you quickly become angry :)
I recommend having 960 wide at 60 fps as well.