My export won't maintain my custom aspect ratio

Hello,

I've searched all over the web and tried exporting through fcp and compressor and still haven't been able to solve my problem, so I've resorted to making an account here to see if someone can help.

I'm trying to export a video for vine so I need the aspect ratio to be a square. For some reason every time I export with a custom aspect ratio of 480x480, it changes to about 260x480, creating an ugly, vertical rectangle. What am I doing wrong?

What are your project settings? If the project is not square are you doing a crop in compressor to make it square?

I created a project and dragged a clip into the project. I used cmd-J to get to the project properties and modified the size to be 480x480. I set the clip spacial conform to Fill. Export gives me a 480x480 ProRes master file.

I opened the file with compressor. I created a new setting and set the frame size to automatic. It recognized that the source was 480x480 with a square aspect ratio. For this test I used H.264.

No issues. My master file was 38 MB (7 second clip) and the H.264 version was 6.5 MB.