[SOLVED] Video Aspect Ratio problem

[EDIT: I have set Anamorphic to None in Dimensions and Constant Framerate in Video in my H.264 encoding software (HandBrake) and now it’s ok]

I admit I know nearly nothing about digital video, but this seems really weird: I have a .mp4 video that I want to import in C10.5 Pro. The Cubase Import Video dialog window gives me the following info: MPEG4 Video File - H.264 - 25 fps - 64000 frames - 700 x 346 (461 x 346) pixel.

Then I import it, but when I play it the Cubase Video Player shows it in a square-ish (4:3ish) window instead of a rectangular (16:9ish) one, resulting in the left and right portions of the video totally cut down.

I have tried every mouse right-click Aspect Ratio option of the video Player: None; Internal; Externa; but I can’t get to see the left and right sides of the video. In e.g. Windows Media Player it is showing perfectly instead (Windows file explorer File Properties -> Details, returns me a 700 x 346 Aspect Ratio): in MP it has a 16:9ish appearance, with black bands on the top and on the bottom, i.e. how it should be.

What can I do?