Recording - Output settings to record AC3, error?

[Fussybob]

I'm feeding a Fire TV Stick 4K into a Hauppauge PVR2 GE+ with a HDMI Cable.

For some reason OBS will only give me sound when the audio input is only stereo and that's ok. I get great video and AAC audio in my recording.

I have now set OBS to Output Record using AC3 which I need to burn Blu-Ray disks.
I click on Start Recoding I get an error.
The Output Record settings are shown below, and the error message.
Are my settings wrong?

 

[koala]

You need to choose a container that supports the combination of the video encoder and audio encoder.
*.ac3 is probably an audio-only container, so it's invalid for a file that should contain both audio and video. There are also quite some limitations on containers, so it isn't possible to use arbitrary video encoders with arbitrary audio encoders in every container format. As far as I know, only *.mkv allows this. You should consult your bluray writing software what source container format it will accept.