Ok, from the log:
10:57:31.917: base resolution: 1280x720
10:57:31.917: output resolution: 1440x810
You're scaling UP from your base resolution, which is already higher than the resolution of the material you're trying to record. If you're not doing this intentionally, reconsider setting the base and output resolution to the same resolution as your capture device and your source material, which is 640x480.
10:57:32.852: coreaudio: failed to find device uid: AppleUSBAudioEngine:Unknown Manufacturer:AV TO USB2.0:14100000:3, waiting for connection
10:57:32.860: Video Capture Device: Could not initialize device with unique ID '0x14100000534d0021'
It may have been temporary, but it doesn't look like this device is well-supported; the driver doesn't identify the manufacturer, and fails to initialize on the first attempt.
10:57:32.860: - source: 'Video Capture Device' (av_capture_input)
10:57:32.860: - source: 'Audio Input Capture' (coreaudio_input_capture)
You appear to have added two devices. Most capture devices that function similar to webcams provide both audio and video. Video device drivers are exclusive, so it may be that what happened here is that OBS capturing the video kicked the audio capture offline. Unless the instructions for your device specifically instruct to add video and audio captures separately, you should probably be configuring it as a video device only, and making sure that capture works for both. The descriptor "av_capture_input" indicates both Audio and Video, hence av).
10:58:49.025: Video Capture Device: Device with unique ID '0x14100000534d0021' connected, resuming capture
10:58:49.025: Video Capture Device: Selected device 'AV TO USB2.0'
10:58:49.033: Video Capture Device: Preset 1280x720 not available
10:58:49.033: Video Capture Device: Using preset 640x480
Make sure you choose a resolution supported by the device, which is 640x480. It's possible that if you have it set to try and use 720p, it may attempt to revert to that and interrupt the connection during recording.
10:59:44.658: Video stopped, number of skipped frames due to encoding lag: 38/714 (5.3%)
OBS Studio - Free and open source software for live streaming and screen recording - obsproject/obs-studio
obsproject.com
You are overloading your CPU with your encoding settings. CPU overloads can cause errors processing audio; although it's also just as likely that the Mac lost connection to the device and did not restore the audio connection. Lowering your canvas/output resolutions to the native resolution of the device should lower this load, but I would look at getting a different capture device for this purpose.
