[ashlar]

kusanagi, mind walking everybody through the steps you take to achieve what we seek with ffdshow raw?

I think you go to the "Resize & aspect" tab and activate resize, using "Specify aspect ratio" and setting it at 16:9.

Then go to the borders submenu, activate "Outside" borders, leaving Percent at 0%, Dividing borders at 50 for both Vertical and Horizontal and Brightness at 0 (we want black bars, not grey ones).

Is this correct?

The only doubt that I have with this setup is that something happens to the picture itself. It doesn't appear like it but... I'm not sure the resize algorithm, once activated, is smart enough not to work on the whole picture. Which might be fine and dandy for 1080p 1.85/2.35:1 material (as the video portion won't be resized) but... let me check with SD stuff fullscreen (1.78).
Yes, ok... with SD stuff, everything seems fine if you have black borders to add. But if you don't have borders to add, unfortunately, ffdshow's rescaling algorithm will activate for the video content, bypassing madVR's more advanced one.

My suggestion is to combine your approach with mine, activating ffdshow raw only in case there are black bars, so only for 1.85|2.20|2.35|2.40 aspect ratios.