MKV to Bluray, wrong aspect ratio

[mochevolete]

I followed a simple guide to convert MKVs to Bluray, this guide involves Tsmuxer, BDinfo and HxD for changing the value of the resolution.
If the video is 1280x720 or 1920x1080 no probs, but if the video, like many time is, cropped, the result will have a wrong aspect ratio, from a strange 4:3 to a streched 1920x816 > 1080.

After digging a bit seems that I have to un-crop the video to his original full frame dimension, 1280x720 or 1920x1080.
So... what's the simpliest / fastest way to do this ?
Please don't tell me that I have to re-encode the whole movie ... :(

thanks, Nik
:)

[Guest]

Where did you get the MKV movie?

[mochevolete]

converted from my brother BR ...

[turbojet]

you have to encode to a native resolution

[Guest]

converted from my brother BR ... Why don't you convert from the original disk instead of the MKV?

[mochevolete]

maybe coz my bro is in Germany and me in Italy ?

Thanks Neuron2 for the big support with my issue ...

BTW I've figured myself that I have to reencode the whole movie adding the borders...