What option in mplayer is for size of a window?
 

$HOME/.mplayer/input.conf
How will the option look for setting window size to 100% of a video size?

There are a couple of ways that seem to be useful.

One is to define
in ~/.mplayer/config; you might want to start with 2, perhaps try 3 and see what you get. The number is a multiplier; i.e., 2x, 3x and so on.

The best way I've found, however, is to
(you can alias mplayer to mplayer -fs, for example).

You may want to check the manual page and fiddle with the geometry option.

Hope this helps some.

Thanks. I'm trying to set hotkeys for "1" - to set 0.5x scale, for "2" - 1x and for "3" - 2x. That's why I need $HOME/.mplayer/input.conf.