mencoder tv:// -tv \
driver=v4l2:device=/dev/video0:width=320:height=240:adevice=/dev/dsp:forceaudio:alsa:adevice=hw.2,0 \
-ofps 15 -oac mp3lame -lameopts cbr:br=32 -ovc lavc -lavcopts \
vbitrate=92 -o ./out-low-quality.avi


# You can change framerate up to 25, video bitrate to 800 
# and sound bitrate to 128 or greater to get excellent quality.

##</code><code>##


mplayer -vf screenshot tv:// driver=v4l2:width=800:height=600:device=/dev/video0 -fps 15 

# and that gave me 800x600 video, and after I pressed 's' i obtained 800x600 in the snapshot.
# q to quit

# I did the same for 1024x768, 1280x1024, and 1600x1200 and obtained a 1024x768, 
# 1280x1024, and 1600x1200 video and snapshot respectively.

# or get shots from a video
# mplayer -vf screenshot some.avi