# Process command options
while getopts ":h" opt; do
case $opt in
h ) display_help
exit 0 ;;
\? ) display_help
exit 1 ;;
esac
done
shift $(($OPTIND - 1))
# Define a function for returning a process id
function get_pid_by_name()
{
local process_str
echo "Searching process $1..."
process_str=`ps aux | grep "$1" | tr --squeeze-repeats '[:blank:]+' '\t' | cut -f 2`
if [ -n "$process_str" ]; then
# The process for grep appears in the second field
process_str=`echo $process_str | cut -s -d ' ' -f 1`
if [ -n "$process_str" ]; then
temp_pid=$process_str
echo "The process id is $temp_pid!"
else
echo "The process $1 cannot be found, perfect!"
fi
else
echo "The process $1 cannot be found, perfect!"
fi
}
# Start execute the command
if [ $OSTYPE = 'linux-gnu' ] && [ `hostname` = "QuantumHome" ]; then
if [ -z "$1" ]; then
echo "$error_prefix Please specify the recording and watching mode: watch|nowatch|onlywatch"
exit 0
fi
if [ "$1" != "onlywatch" ] && [ -z "$2" ]; then
echo "$error_prefix Please provide the video file name to be saved!"
exit 0
fi
# Declare the pid as integers
declare -i temp_pid=-1 mplayer_pid=-1 mencoder_pid=-1 tee_pid=-1
get_pid_by_name mencoder
mencoder_pid=$temp_pid
temp_pid=-1
get_pid_by_name tee
tee_pid=$temp_pid
temp_pid=-1
get_pid_by_name mplayer
mplayer_pid=$temp_pid
temp_pid=-1
if [ $(($mencoder_pid!=-1 && $mplayer_pid!=-1 && $tee_pid!=-1)) = 1 ]; then
echo "$error_prefix A tv recording or watching activity is now working, please exit it first!"
exit 0
fi
# Create FIFO named pipe
if [ ! -e "/tmp/tv.fifo" ]; then
echo "$state_prefix FIFO does not exist, now being created..."
mkfifo /tmp/tv.fifo && echo "$state_prefix Creating FIFO successful!"
fi
# Start tee and mplayer
case "$1" in
watch ) echo "$state_prefix Start recording tv and watch it using mplayer..."
# Note: sudo must be used in order to make mplayer appear
cat /tmp/tv.fifo | tee -a "${2%.avi}.avi" | sudo -u orlando DISPLAY=:0.0 mplayer -cache 51200 -framedrop -ao sdl -vo xv - & ;;
nowatch ) echo "$state_prefix Start recording tv without watching it..."
cat /tmp/tv.fifo | tee -a "${2%.avi}.avi" & ;;
onlywatch ) echo "$state_prefix Start watching tv without recording it..."
# Note: "tee -a -" will not work here
cat /tmp/tv.fifo | tee | sudo -u orlando DISPLAY=:0.0 mplayer -cache 51200 -framedrop -ao sdl -vo xv - & ;;
* ) echo "$error_prefix Please specify the recording and watching mode: watch|nowatch|onlywatch"
exit 0;
esac
# Start mencoder to feed the video stream into FIFO
echo "$state_prefix Now start mencoder to capture tv..."
mencoder tv:// -tv driver=v4l2:device=/dev/video0:norm=PAL:alsa:adevice=hw.2,0:amode=1:audiorate=48000:forceaudio:volume=100:immediatemode=0:normid=8:input=1:buffersize=1024:width=768:height=576:outfmt=i420 -oac mp3lame -lameopts fast:preset=standard -ovc lavc -lavcopts vcodec=mpeg4:vhq:vbitrate=1800 -o /tmp/tv.fifo
else
echo "$warning_prefix Operating system or host name is not supported!"
fi
该脚本程序中，mencoder的参数较为复杂，这里对其解释如下：
driver=v4l2：使用video for linux驱动；
device=/dev/video0：视频卡设备节点。只有当驱动安装正确后，才会出现该节点；
norm=PAL：指定模拟电视制式，中国为PAL；
alsa：从ALSA捕获音频；