Hi, All!
ffMpeg -timstamp
option works
There used to be a drawtext filter.
ffmpeg -i in.mp4 -vf "drawtext=fontfile=/usr/share/fonts/truetype/DroidSans.ttf: timecode='09\:57\:00\:00': r=25: \
x=(w-tw)/2: y=h-(2*lh): fontcolor=white: box=1: boxcolor=0x00000000@1" -an -y out.mp4
See here: http://ffmpeg.org/trac/ffmpeg/wiki/FilteringGuide
I believe you can replace the exact time code with a sprintf like syntax.
ffmpeg -f video4linux2 -i /dev/video0 -s 640x480 -r 30 -vf \
"drawtext=fontfile=/usr/share/fonts/truetype/ttf-dejavu/DejaVuSans-Bold.ttf: \
text='\%T': fontcolor=white@0.8: x=7: y=460" -vcodec libx264 -vb 2000k \
-preset ultrafast -f mp4 output.mp4
See here: http://einar.slaskete.net/2011/09/05/adding-time-stamp-overlay-to-video-stream-using-ffmpeg/