Recording the Desktop, Camera, and Mic, in OpenBSD

I've been needing to start recording some videos again, and I wanted to make sure to do so without having to go back to Linux or macOS. So I looked up the intricacies of how I might do this using OpenBSD, as that is what I currently have on my laptop.

I've been quite happy with OpenBSD overall. It's not very complicated to use, and the suspend/resume works really well.

I still need to really test out what I've posted here, and see how smooth this is going to be, and if the audio will be in sync. The last time I was trying this I had troubles with the voice audio being in sync. So there may be some other settings to add, but this is a good starting point.

This laptop model is Lenovo T460s. I am using a Logitech HD Pro Webcam C920. The camera also has a microphone.

Before being able to record, you must enable audio and video recording.

doas sysctl kern.video.record=1
doas sysctl kern.audio.record=1

I am also wanting to record by using my normal system user, so I am changing the video devices ownership to my user:

doas chown jon /dev/video0
doas chown jon /dev/video1

When I'm done, I just change them back. I have scripts to do this:

# Disable recording once more.
sysctl kern.video.record=0
sysctl kern.audio.record=0
chown root /dev/video0
chown root /dev/video1

Once I am ready to record, I run this script:

ffmpeg \
        -f sndio \
        -thread_queue_size 4096 \
        -i snd/1 \
        -video_size 1920x1080 \
        -f x11grab -i :0 \
        -f video4linux2 \
        -video_size 640x480 \
        -thread_queue_size 4096 \
        -i /dev/video1 \
        -filter_complex "overlay=main_w-overlay_w-5:main_h-overlay_h-5" \
        -c:v libx264 \
        -preset ultrafast \
        -crf 18 \
        output.mp4

The first section gets the audio, then the screen, then the camera. Then the "filter_complex" puts the video overlayed, and in the bottom right corner.

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