timelapse.sh

#!/bin/bash

# Timelapse script by Ben Scholzen 'DASPRiD'
# Licensed under the Simplified BSD License 
# http://opensource.org/licenses/BSD-2-Clause

FFPROBE=/usr/bin/ffprobe
FFMPEG=/usr/bin/ffmpeg
SOXI=/usr/bin/soxi
SPLASH_LENGTH=5

INPUT_SPLASH=$1
INPUT_VIDEO=$2
INPUT_AUDIO=$3
OUTPUT_FILE=$4

VIDEO_LENGTH=$($FFPROBE -i "$INPUT_VIDEO" 2>&1 | grep Duration | awk '{print $2}' | tr -d , | awk -F':' '{print $1 * 60 * 60 + $2 * 60 + $3}')
AUDIO_LENGTH=$($SOXI -D "$INPUT_AUDIO")

PTS=$(echo "scale = 15; 1 / ($VIDEO_LENGTH / ($AUDIO_LENGTH - $SPLASH_LENGTH))" | bc | awk '{printf "%.15f", $0}')

# First we will create the splash video part in a lossless format
SPLASH_TEMP=$(mktemp --suffix=.mp4)
$FFMPEG -loop 1 -i "$INPUT_SPLASH" -t $SPLASH_LENGTH -c:v libx264 -pix_fmt yuv420p -preset ultrafast -qp 0 -y "$SPLASH_TEMP"

# Then create the final timelapse
$FFMPEG \
    -i "$SPLASH_TEMP" \
    -i "$INPUT_VIDEO" \
    -i "$INPUT_AUDIO" \
    -filter_complex "[1:v]setpts=$PTS*PTS [tl]; [0:v] [tl] concat=n=2:v=1:a=0 [v]" \
    -map '[v]' -map 2:0 \
    -codec:v libx264 -pix_fmt yuv420p -profile:v high -preset slow -b:v 4m -maxrate 4m -bufsize 8m -threads 0  \
    -codec:a libvo_aacenc -b:a 192k -ac 2 -ar 48000 \
    -shortest \
    -y \
    "$OUTPUT_FILE"

rm -f "$SPLASH_TEMP"