Batch M4V to MKV? (MKVMerge)

Hi Guys,

I've read as much as I could find on MKVMerge command line, but I'm really struggling as a newb...

My goal is to convert a large number of Itunes (DRM Free) M4V files to MKV files, maintaining the same audio/video contents.

I've seen this command thrown around, and I imagine I could simply edit is, as I did below... However, I'm not sure how to use it:

FOR %I IN (*.avi) DO mkvmerge -o %I.mkv %I

to

FOR %I IN (*.m4v) DO mkvmerge -o %I.mkv %I

Do I simply put it in a batch file, in the same directory as the videos?

Do I put it in the MKVToolNix directory?

Do I need to include the program/input/output paths?

Nothing I've tried seems to work.

Any help would be really appreciated!

The file names have spaces in them, if it matters...
Thanks