Learn about the Scale tab settings in the Recording category when you click Tools-Options in the OCam menu.

 
If you check the video size adjustment, the video is resized according to the resolution and quality you set.
Supported resolutions (presets) are as follows.

4320p UHD 8K (7680x4320)
2160p UHD 4K (3840x2160)
1440p QHD (2560x1440)
1080p FHD (1920x1080)
720p HD (1280x720)
480p (854x480)
360p (640x360)
240p (426x240)
144p (256x144)
120p (160x120)
96p (128x96)
Half size
Fit width

Fit height
Custom

For 8k video, only MPEG-4 codec is supported. Besides, 8k resolution is not supported because codec is not supported.

Even in the case of an external codec, some resolutions may not be supported, so recording may not be possible.

Half size resizes the movie to half the size of the recording area.

You can specify the width only and the height is fixed so that the user can specify the horizontal resolution. In the height, the video is resized to the vertical resolution of the recording area.

Specify portrait only and lock horizontally allows the user to specify the vertical resolution, while horizontal resizes the video to the horizontal resolution of the recording area.

Custom resizes the video by directly entering the final video size you want to resize.

Quality refers to the quality of the recorded video when the video is resized. The higher the quality, the slower the video resize rate. The lower the quality, the faster the video resize rate.