New years resolution?

No, what is your video resolution from your monitor? May not seem important, unless you need to get a replacement monitor that will support your existing setup or you need to do some desktop video such as the command:

$ avconv -f alsa -i hw:1 -f x11grab -r 25 -s 1280x768 -i :0.0 -vcodec libx264 -threads 4 file.avi

In this case it is 1280x768. Of course you could use a smaller portion of the desktop to capture. So how do we find the desktop resolution. There are several ways. The least verbose:

$ xdpyinfo  | grep 'dimensions:' 
    dimensions:    1280x768 pixels (338x203 millimeters)

But if you wanted more information try:

$ xrandr
Screen 0: minimum 320 x 200, current 1280 x 768, maximum 4096 x 4096
VGA-0 disconnected (normal left inverted right x axis y axis)
LVDS connected 1280x768+0+0 (normal left inverted right x axis y axis) 305mm x 183mm
   1280x768       60.0*+
   1280x720       59.9 
   1152x768       59.8 
   1024x768       59.9 
   800x600        59.9 
   848x480        59.7 
   720x480        59.7 
   640x480        59.4 
S-video disconnected (normal left inverted right x axis y axis)

or you could use a gui tool.

Be sure to research avconv the replacement for ffmpeg.