.mkv resolution questions

[micro9mm]

A friend gave me a .mkv file that I'm trying to convert into something playable on my blu-ray player. The file is aproximately 15gb HD file, but I am confused as to why it has a resolution of 1920x1040 (as opposed to typical blu-ray content being 1920x1080, right?). Ive been reading many guides and have settled on methods using tsmuxer to remux and build the blu-ray files but I'm afraid that sense this method does not re-encode the video that the resolution will be out of whack/stretched on the blu-ray?

[tkolt]

use uncropmkv if you want, it will "fix" resolution

[jagabo]

Probably because the source was a 1.85:1 AR movie and whoever made the MKV cropped away the black borders. To make it compatible with Blu-ray players you have to restore the original 1920x1080 frame size by adding the black borders back.