video shots with ffmpeg

videoshot.sh

#!/bin/sh

function random()
{
	duration=`./ffmpeg -i "${file}" 2>&1 | grep "Duration"| cut -d ' ' -f 4 | sed s/,// | sed 's@\..*@@g' | awk '{ split($1, A, ":"); split(A[3], B, "."); print 3600*A[1] + 60*A[2] + B[1] }'`
	# echo "$duration"
	min=15

	if [ $duration -gt $min ]
	then
		r=$RANDOM
		m=`expr $duration - $min`
    	mr=$(($r%$m))
    	mr1=`expr $mr + $min`
    	echo $mr1;
    else
    	mr1=`expr $duration - 1`
    	echo $mr1;	
	fi
}

if [ $# != 2 ]; then
	echo "usage: videoshot.sh /Users/danny/MyVideoDir /Users/danny/MyImageDir"
	exit -1
fi

inputDir=$1
outputDir=$2
binaryEXE=./ffmpeg 

fixImageDir=$outputDir/snaps

if [ ! -f "$binaryEXE" ]; then
	echo "sorry, not found ffmpeg command line tool"
	exit
fi

if [ ! -x "$fixImageDir" ]; then
  mkdir "$fixImageDir"
fi

for file in $inputDir/*.mp4
do
	nameNoSuffix=${file%.*}
	name="${nameNoSuffix##*/}"

	imageName=$fixImageDir/$name.jpg
	n=$(random)

	# echo "./ffmpeg -y -hide_banner -ss $n -i $file -vf scale=400:-1 -frames:v 1 -g 0 -f mjpeg $imageName"
	./ffmpeg -y -hide_banner -ss $n -i "${file}" -vf scale=400:-1 -frames:v 1 -g 0 -f mjpeg "${imageName}"

done;

open -R "$fixImageDir"