Create youtube storyboards from VOD videos using FFMPEG

ffmpeg-yt-storybaord.sh

#!/bin/bash

# Storyboard frequency:
# 
# 0      -  2 min, every 1  sec.
# 2 min  -  5 min, every 2  sec.
# 5 min  - 15 min, every 5  sec.
# 15 min +         every 10 sec.
# 
# Storyboard size:
# 
# 1:  5x5  @ 160x90 => 800x450px
# 2: 10x10 @  80x45 => 800x450px

INPUT="$1"
DURATION="$(ffprobe -i "$INPUT" -show_entries format=duration -v quiet -of csv="p=0")"

if (( $(echo "$DURATION < 2*60" | bc -l) )); then
	FPS=1
elif (( $(echo "$DURATION < 5*60" | bc -l) )); then
	FPS=1/2
elif (( $(echo "$DURATION < 15*60" | bc -l) )); then
	FPS=1/5
else
	FPS=1/10
fi

echo "Duration is $DURATION"
echo "FPS is $FPS"

ffmpeg -i "$INPUT" \
    -vf "fps=$FPS,scale=80:45,tile=10x10" -an -vsync 0 -start_number 0 "storyboard_L1_M%d.png" \
    -vf "fps=$FPS,scale=160:90,tile=5x5" -an -vsync 0 -start_number 0 "storyboard_L2_M%d.png";