OBS is not DVD mastering (or ripping) software.
"DVD standards" is a wide-open field, and will depend on what your DVD mastering software expects/uses.
You can check Wikipedia for standard DVD resolutions though. SD is normally 480p. HD can be 720p, 1080p, or 2160p.
You definitely can add a profile and set the base canvas resolution as you like to accommodate any AR needed, by simply typing it into the Settings->Video canvas and output boxes.Thanks for your reply.
It is exactly what I taught. That's why I asked if my request goes beyond the OBS project.
I'm quite familiar with standard DVD resolutions since I have been authoring DVDs for at least 15 years.
I just asked if the DVD standard could also be included as a separate profile.
Having said that I have managed to get a very close to perfect AR of the picture by stretching the vertical handles of the (red) window frame. All I wanted was to copy part of a DVD movie without having to rip the whole DVD which had an AR of 1.85:1
You definitely can add a profile and set the base canvas resolution as you like to accommodate any AR needed, by simply typing it into the Settings->Video canvas and output boxes.
You can also hold SHIFT while scaling a source to go into non-locked AR mode to correct for off-ratio sources.
Additionally, you can right-click the source, go to Transform, then Edit Transform to assign the size numerically.
Unfortunately, having it as a default profile or common value is unlikely to happen. The dev team aggressively pare back 'potential confusions for new users', especially when there are workarounds for edge or niche cases already present in the software. It's expected that power-users will be able to make do, even if it's somewhat less convenient.