I suppose if there was a way to adjust the dimensions of the timeline to a 1.33 ratio, that would also be a solution.
TLDR
- Open the project settings
- Change the timeline resolution to one with a 1.33 aspect ratio, or enter your own custom resolution in the "for ___ x ___ processing" dialogue.
Explanation
Resolve's resolution independence can be a little confusing when you're coming from other apps. Normally, in other apps, you set your timeline resolution (aka, "sequence resolution") to match your source footage, and then resize or crop to your desired delivery specification when you export.
In Resolve, you do it the other way around: you set your timeline resolution to be the size of what you want to export in the end. Then, any amount of scaling or re-sizing automatically uses the highest quality source available, and transformations are concatenated intelligently by the software.
So, in your case, all you need to do is set the desired timeline resolution, rotate the source footage, and increase the zoom value until all of the black borders are gone. There is no reason to touch the crop controls, because all of the pixels falling outside the dimensions you've chosen don't appear in the final render. They're "cropped" by not getting exported.
I understand the confusion, because cropping in other tools, like Premiere, Photoshop, and AME amounts to changing the size of your working space (artboard, sequence, timeline, or whatnot). In Resolve, the "crop" controls in the inspector don't alter the resolution of the source material OR the export. The only thing Resolve's crop control does is mask the edges of an image, and the only time you might use it is when you're trying to create a quick picture-in-picture effect.
The reason people coming from Premiere find Resolve's resolution independence confusing is that, for close to twenty years, if you started a project with the wrong sequence settings, it was impossible to change them. To fix it, you had to copy your entire sequence into a new one with the correct settings, and then re-frame everything accordingly. Editors learned very quickly to get it right the first time, and crop/scale the export as necessary.
It might take a while to get used to the fact that Resolve presents no barriers to changing your timeline resolution in the middle of a project. But as you do, you'll appreciate the benefits. To name a few, you can:
- Work on a timeline a fraction of the size of your eventual delivery, and enjoy massive performance boosts, then scale up to 8K and beyond when you're ready to export.
- Work on a single timeline and deliver, change the aspect ratio, and deliver for a different social media platform, repeat as necessary.
Additional Notes
Blanking
These days, most platforms are savvy about creating pillarboxes, letterboxes, or scaling your media intelligently, so if you give YouTube a 1.33 video, the player will automatically re-size, and add pillarboxes if it's fullscreen inside a 16:9 display. But you might wonder (and, your question might actually be asking) how to manually add black bars to the top and bottom, or the sides of the image. This is called "blanking."
To add it via convenient shortcut, go to the Timeline menu-> Output Blanking, and select your desired aspect ratio from the list. If your desired aspect ratio isn't in this list, you can dial in any custom one on the Color page-> Sizing tab-> Output sizing dropdown.
Resolve applies these black bars as a final step, so you can be sure that you never accidentally have a title, or any media on top of the blanking.
NTSC
Since you're looking for a 1.33 aspect ratio, you might wonder why none of the preset dimensions in the project settings come out to 1.33 when you divide the width by the height. The reason is because when televisions were shaped 4:3, the standard broadcast didn't use square pixels. Even when digital video first became available to consumers, it didn't use square pixels either. So if you select one of the standard compliant options from Resolve's dropdown menu, like "720x486 NTSC," it will give you a 4:3 image, even though 720/486 ≠ 4/3. This is because Resolve adheres to the original specification, which doesn't use square pixels. You can always enter a custom number in the "for ___ x ___ processing" boxes if you want a nonstandard 4:3 image with square pixels, but you'll have to work out the math depending on how high or wide you want the final image.
