Hi @spotxuv,
I was looking into how this is set up and apparently that specific connection in our docs is incorrect for current QGC, and audio input currently isn’t supported in QGC (my apologies for misleading you).
Companion does stream audio (from our Low-Light HD USB Camera) to UDP:5601 (so you can receive the stream yourself if you want), but QGC audio receiving was apparently only available back when Blue Robotics had a custom fork. We apparently tried to add it to mainstream QGC after we’d merged across, but that pull request was put on hold while waiting for some other changes elsewhere, and has since been closed. It’s not clear why the PR was closed, so I’ve asked about it in the open issue on supporting audio recording.
Having re-read your post, it’s also not clear whether you’re wanting to record audio from the vehicle (which I assumed was the case), or from the topside (e.g. for narrating operation). Regardless, the recording will unfortunately need to be done external to QGC, so there may be some adjustment required to get things synched, and/or some muxing to add the audio to the video file afterwards.