Convert video by mencoder

mencoder is cross-platform command line video decoding, encoding and filtering tool. it can convert all the formats that MPlayer understands.

a converting example like below

mencoder in.video -oac mp3lame -lameopts preset=64 -ovc lavc -lavcopts vcodec=mpeg4 -ofps 25 -vf scale=320:240 -ni -o out.video

-oac #encode with the given audio codec (no default set).
-oac help #get a list of available audio codecs.
-<codec>opts #codec specific encoding parameters

preset=<value> #ABR encoding at average given kbps bitrate

-ovc #encode with the given video codec (no default set).
-oac help #get a list of available video codecs.

vcodec=<value> #employ the specified codec (default: mpeg4).
#windows media player comptiable format: msmpeg4, msmpeg4v2, wmv7

-ofps #specify a frames per second (fps) value for the output file
-vf scale=x:y #resize video

-ni #force usage of non-interleaved AVI parser (fixes playback of some bad AVI files).

-o #output filename

Set up an mp3 alarm on CentOS

1. Make sure the user who will run the alarm is not in /etc/cron.deny
2. Log in as the user then type crontab -e for editing his cron entry
# dom = Day of Month
# dow = Day of Week
# m h dom mon dow command
42 07 * * 1-5 /usr/local/bin/alarm
3. vi /usr/local/bin/alarm

# run xterm to execute mplayer in another window
# with the parameter, display 0 you can quit playing easily,
# the parameter -loop 0 means repeat forever.
/usr/bin/xterm -display :0 -bg black -fg white \
-e /usr/local/mplayer -loop 0 filename.mp3


/usr/bin/mplayer -loop 0 filename.mp3

4. Remember to give permission of execution to alarm
chmod 7xx alarm

5. An easy way to stop playing, use the command pkill

pkill mplayer