ffmpeg - resize and crop

Question

I want to know how to use the scale filter to take an image that is 2154x1136 and scale it down exactly 89.04% such that the image sits in a 1920x1080 frame, with full image left and right and black letterboxing top and bottom. Using

vf scale=1920:-1

gets me close. But the resulting file is 1920x1013 and I need to add black pixels top and bottom to fill it out to 1920x1080.

I have other issues including how to feed ffmpeg a dpx sequence and get back an Avid-ready MXF while applying a shot specific cdl file and a show specific display lut, but I need to walk before I can run so a bit of help with this first puzzle is what I'm asking for now.

Thank you in advance.

Answer 1

Use this:

-vf "scale=iw*min(1920/iw\,1080/ih):ih*min(1920/iw\,1080/ih), pad=1920:1080:(1920-iw*min(1920/iw\,1080/ih))/2:(1080-ih*min(1920/iw\,1080/ih))/2"

This code evaluates which ratio to apply for scaling, then scales it and finally applys the requisite amount of padding.