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:
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
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.