Nathan Campos

GoPro cameras are great to have around. I have several very old models and a couple of knockoffs as well. They capture great footage and have a plethora of accessories to mount them to nearly everything you can imagine. Because of this they are great for documenting moments and specially documenting projects or work you are performing.

They come specially useful for timelapses and the camera has a special mode just for these. In timelapse mode the camera will take a picture every X number of seconds (set in the camera settings). The camera stores these timelapse images in the same place, and in the same way, as if they were manually taken by you, which means that if you took pictures before and after the timelapse you'll have to separate them manually.

The real problem comes when you get to the computer and you want to combine these images into a video, which is always the ultimate goal of a timelapse. Bacause the camera stores the timelapse photos in the same manner as regular photos, this means it'll create a new folder each time the file index overflows. For example: Pictures start at G0020001.JPG and when they reach G0020999.JPG a new folder will be created and the process will start over, just like every digital camera you ever had.

That wouldn't be such a big deal, you could always copy the contents of each folder into another one and simply point a timelapse program at this new folder and you would be done. The issue is that because of the way the camera indexing works, and the fact that, if you are running a timelapse for many hours, the counter will eventually wrap around itself and you'll end up with pictures taken hours apart that have the same filename, making it impossible to dump them all in the same folder without having them overwritten or getting them mixed together.

The only solution to this is to create individual timelapse videos of each folder and then combine these videos into a single timelapse. Since this is quite a time consuming task, I've decided to write a simple bash script to make the whole proccess fully automated:

#!/bin/bash

# Go through directories building videos from them.
echo "Generating a timelapse for each folder created by the camera..."
index=0
for dir in *; do
	if [ -d "$dir" ]; then
		pushd "$dir"
		fname=`printf "../%03d.mp4" $index`
		ffmpeg -framerate 30 -pattern_type glob -i "*.JPG" -c:v libx264 \
			-crf 18 "$fname"
		popd

		((index++))
	fi
done

# Concatenate the videos into a single one.
echo "Concatenating videos into a continuous timelapse..."
printf "file '%s'\n" *.mp4 > videolist.txt
ffmpeg -f concat -i videolist.txt -c copy timelapse.mp4
rm videolist.txt

# Make a 1080p version for ease of sharing.
echo "Creating a 1080p version of the timelapse..."
ffmpeg -i timelapse.mp4 -vf 'scale=-2:1080' -c:v libx264 -crf 18 \
	timelapse-1080p.mp4

echo "Done"

Simply place this script in the folder with the timelapse footage from the camera and the script will create the individual videos of each folder at the original resolution of the pictures, ensuring you have a high resolution archival copy of the timelapse, leaving you the option of deleting the original pictures, and it'll also create a 1080p (respecting the original aspect ratio) version of the video for sharing purposes.