Difference between PX4 firmware and Ardupilot firmware

I am trying to understand what the differences in firmware are between PX4 and the Ardupilot firmware. I have a video system that seems to only want to work with the PX4 firmware on telem1 of my Pixhawk for OSD. If I try using the Ardupilot firmware than it doesnt want to work. I am confused as to how this is happening. They both use Mavlink1/2 for communication, so why are the outputs different.


Both firmware are very different from the lower driver system to the higher control logic. So they aren’t compatible.

Ideally, the MAVLink would have allow to share input and output from both firmware. But its lacks of standardization is playing against it. Only the MAVLink message format is standardized (and it still may vary between implementation), message’s content isn’t standard. That why some message will work on Px4 and not on ArduPilot and vice et versa.
We try to keep in sync with PX4 message but on the stable release it generally won’t match on both side due to the different release cycle…our stable release will only get bug fix support and rarely update message support.

Now, about your OSD, could you share which one it is and what software it has (in sum, the max info you get on it). With those info we could work on supporting it on next releases.

It’s not really an OSD. It’s more of a video system I found. The system is called WiDV, and I dont know enough to understand the difficulty of getting it working or compatible with the Ardupilot firmware.

Here’s a link to the system I’m trying out. The purpose was I needed a video system/OSD with a wide range of cameras with HDMI output and I couldn’t find any other solution.