video chapters

filelength=$(echo "60 90 120" |awk '{print $1+$2+$3}'); chapterlength=$(echo "$filelength 6" |awk '{print $1/$2}'
); echo "chapter length: $chapterlength"; file1=60;file2=90;file3=120; remfile1=$(echo "$file1 $chapterlength" |a
wk '{print $1-$2}'); echo "remainder from file1: $remfile1"; echo "chapter 1: 0,$chapterlength"; file2offset=$(ec
ho "$chapterlength $remfile1" |awk '{print $1-$2}'); echo "file2offset: $file2offset"; chapt3=$(echo "$file2offse
t $chapterlength" |awk '{print $1+$2}'); echo "chapter 3: $file2offset,$chapt3"; remfile2=$(echo "$file2 $chapt3"
 |awk '{print $1-$2}'); echo "remainder from file2: $remfile2"; file3offset=$(echo "$chapterlength $remfile2" |aw
k '{print $1-$2}'); echo "file3offset: $file3offset"; chapt5=$(echo "$file3offset $chapterlength" |awk '{print $1
+$2}'); echo "chapter 5: $file3offset,$chapt5"; echo "chapters: 0,$chapterlength $file2offset,$chapt3 $file3offse
t,$chapt5"; 
chapter length: 45
remainder from file1: 15
chapter 1: 0,45
file2offset: 30
chapter 3: 30,75
remainder from file2: 15
file3offset: 30
chapter 5: 30,75
chapters: 0,45 30,75 30,75