Headless ambilight not working

Hi,

I have got the following setup:

Shield TV (Pro) -> A/V Receiver -> HDMI (MAIN) -> TV
                                   HDMI (SUB) -> HDMI2USB -> RPi (Raspbian) -> APA102 leds

(The A/V receiver has two HDMI out which I can set to output at the same time, so I am using it as a splitter)

I have a switch to power of the Pi and the led power supply. That just turns off the power, so no safe power down or anything. This used to work. The Pi does not have a monitor attached btw.

So now the actual problem: When I power it off like mentioned below and start it again, it doesn't work anymore. In the console I see the deamon was started but exited with an error: "V4L2GRABBER ERROR: Cannot identify '/dev/video0' ERROR 2, No such file or directory". When I attach a monitor to the Pi and try running it again it seems to work again.

So I suspect some driver is not being loaded when there is no monitor attached to the Pi. I have been searching a lot on the internet, but can't find anything on this. I did find a lot of topics on /dev/video0 not found, but those all seem to have a different problem. The solutions suggested I found didn't work for me or were not applicable.

Anyone has an idea what I should do to get this to work all the time?

I tested a bit more. It also works when I SSH into my Raspberry, and reboot it when the AV receiver is already on. Then I have to open an SSH session again, so the script actually runs. What confuses me, is that I had it working before and I don't feel like I changed anything.

It comes down to these two problems:
- I have to reboot the Pi after turning on the AV receiver so it actually loads the /dev/video0 driver(?)
- I have to SSH into the Pi after the reboot to make sure the bash-script that should run automatically on startup actually starts. When I connect via SSH I see hyperion is running and I get the output there. So I can't input any commands either.