timelapse-prepare-and-run-ffmpeg.sh

This bash script makes a 25 fps time lapse video and according subtitle file with timestamps based on date-named JPG files using ffmpeg. Input is the current directory, all JPG files are processed in order of filename alphabetically. It does not have any input parameters.

name    : timelapse-prepare-and-run-ffmpeg.sh
author  : leo sauermann
date    : 2021-05
license : https://opensource.org/licenses/MIT
seeAlso : https://github.com/leobard/timelapse-prepare-and-run-ffmpeg.sh

Running

$ ./timelapse-prepare-and-run-ffmpeg.sh

Input filenames

precondition: the files are named using exiftool already and start with the date and time

example beginnings of filenames:

2021-05-17_0025
2021-05-17_00250543.jpg
2021-05-17_00250543-2021-05-17_00250705.jpg

How to rename a directory of photos from IMG001.JPG to above:

cmd.exe version:

exiftool "-FileName<${datetimeoriginal}${subsectimeoriginal}%-c.%e" -d %Y-%m-%d_%H%M%S . 

bash version:

exiftool '-FileName<${datetimeoriginal}${subsectimeoriginal}%-c.%e' -d %Y-%m-%d_%H%M%S . 

The files may also be handled by enfuse beforehand, then the names are concatenated and longer 2021-05-17_00250543-2021-05-17_00250705.jpg

Output files

The script will generate three output files

video.mp4
video1080.mp4
subtitles.srt

Videos

The two video files are: video.mp4 in original resolution and video1080.mp4 scaled to 1080 pixel vertical resolution.

Subtitles

The subtitle file subtitles.srt stores the date and time of each frame as subtitle of length 0.04 seconds. That is 25 frames per second. These are intended as meta-data for further post-processing.

Example of a block of the resulting SRT:

1
00:00:00,040 --> 00:00:00,080
2021-05-17 00:25