GoPro Hero 3+ Black needs not only VSYNC but also HSYNC for genlock, today we found by investigating signals from Dual Hero Bacpac. Thus it never be possible that slow microprocessors like Arduino Pro Mini act as a generator for HSYNC pulses of microsecond-order period.
Capturing in 3D two Hero 3+ Black cameras are now known to work in a strictly synchronized manner: they sync both at the beginnings of every horizontal line (HSYNC) and at the starts of every frame (VSYNC). We thought that VSYNC was suffice, thus we wrote “Genlock MewPro Is Coming Soon” as the previous post in the blog. But that is proved to be not so easy to coming soon. We are now planning to make something new to sync two or more GoPros by using MewPros and an external HSYNC/VSYNC generator. So please stay following this blog if you are interested in genlock.
We wrote in the previous post that VSYNC is the simple pulse wave of period equal to the frame time and of duration 5μs at pin 10 in Herobus. HSYNC is also a simple pulse wave, which is at pin 20 in Herobus (the pin is formerly known as “Left Audio Out” or “pin 11”). For your information we publish the pinout of the white cable between the left and the right bacpacs of Dual Hero System:
Today, we succeeded in feeding the external frame sync signal to GoPro Hero 3+ Black. So we proudly announce that the next version of MewPro application will be with (or without) genlock.
Radosław Gezella, who is working with about 30 GoPros (!) in a rig, wrote us an e-mail about 10 days ago. It described that video frame sync signal is located at pin 21, which is in our pin-ordering “pin 10”, in Herobus of Dual Hero bacpac. And also he told us that this genlock signal is the simple pulse wave of period equal to the frame time and of duration 5μs.
Based on his findings we finally got MewPro worked with genlock (In order to do some reverse-engineering experiments we needed to purchase an original Dual Hero and to make a hardware emulator of GoPro Hero 3+ Black). Related source codes and schematics will be published in this site soon. Fortunately, no modification to existing MewPro hardware is required to sync many GoPros with genlock.