Sometimes there are video files that have the wrong aspect ratio (AR). Therefore, need such a function. MPC-HC has this feature. This is a very important function, which is severely lacking Please add it asap
Media Player Classic - Home Cinema (instead of a AR is 16:9, by default the AR is 4:3):
Test video: Bleeding Through - Line in the Sand.mpg
We plan to add in future versions of Splash forcing aspect ratio for both video and display.
The video is for the issue described by your, and display is for older plasma/lsd tvs that support low 4:3 resolution for PC input only.
This features are included in our plans but there is no date defined yet when will be avialable.