#!/bin/bash

# scene detection

# needs: ffmpeg, mediainfo, tee, awk

maketmpdir () {
    # tmp dir http://mywiki.wooledge.org/BashFAQ/062
    # delete old one first
    [ -n "$tmp" ] && rm -fr "$tmp"
    # busines as usual
    tmp="/tmp/$RANDOM-$$"
    trap '[ -n "$tmp" ] && rm -fr "$tmp"' EXIT
    mkdir -m 700 "$tmp" || { echo '!! unable to create a tmpdir' >&2; tmp=; exit 1; }
}

# func
calc () {
    echo "scale=5; $*" | bc
}
awk_round () {
    awk 'BEGIN{printf "%."'$1'"f\n", "'$2'"}'
}

# action
while [ $# -gt 0 ]; do

    maketmpdir

    file=$(readlink -f "$1")
    echo "$file"
    
    # non-reliable scene detection
    ffmpeg -hide_banner -i "$file" -an \
           -filter:v "select='gt(scene,0.2)',showinfo" \
           -f null \
           - 2>&1 | tee "$tmp/all.txt"
    
    echo ; echo "$file cut detection points in seconds"
    echo "0" > "$tmp/greped.txt"
    grep showinfo "$tmp/all.txt" | grep "pts_time:[0-9.]*" -o | grep "[0-9.]*" -o | tee -a "$tmp/greped.txt"

    echo ; echo "$file timeline" 
    # echo simple timeline
    # ||------------|----|-----|----|----|||||||||||||||----|-|--|--|-|-|||
    { read -r v2; while v1=$v2; read -r v2; do 
        
        dur="$(calc "$v2 - $v1")"
        echo "$dur" >> "$tmp/dur.txt"
        round="$(awk_round 0 "$dur")"

        if [ "$round" -ne "0" ]; then
            printf '%0.s-' $(seq 1 "$round")
        fi
        
        printf "|"

        
    done; } < "$tmp/greped.txt"


    # echo average length
    echo
    awk '{s+=$1}END{print "average clip length:",s/NR,"seconds"}' RS="\n" "$tmp/dur.txt"
    
    # various info
    # fps, duration
    #fps="$(mediainfo --Inform="Video;%FrameRate%" "$file")"
    #dursec="$(mediainfo "--Inform=General;%Duration%" "$file")"
    durfile="$(mediainfo "--Inform=General;%Duration/String1%" "$file")"
    
    shots="$( cat "$tmp/dur.txt" | wc -l )"
    echo "$shots clips, $durfile"

shift
done