I just found one mp4 on my PSP and used mkvmerge to make it mkv and now i'm trying with it
What happens when you use the mkv after mkvmerge? Doesn't it recognize the aac audio, because with my file it shows and is muxed in the final -uncropped.mkv as aac. And eac3to won't encode aac to ac3 without nero directshow filter (which I don't have)... duh...