General
The videos are simply collections of static images concatenated into a movie. We capture one image (frame) every N (currently 30) seconds from the camera. We try to keep the capture interval consistent on average; if an image interval is 32 seconds the next image will be pulled at 28 seconds. On my todo list is raising the capture rate and creating the movies such that the image timestamps are used to moderate the gaps between the images.
Looking at 15April2016; we captured 1925 images, 2 a minute, from 0511 to 2108. Approximately 16 hours. The maths work out, 1925 / 2 / 60 = 16.04. Then, 1925frames at 15fps gives us a 2:08 minute movie. Voila!
Create
The time-lapse videos are created with Linux command line tools. memcoder concatenates (for want of a better understanding) the collection of static images. Then ffmpeg converts and compresses it. The commands I use are similar to:
Commands:
mencoder -msglevel all=1 -nosound -noskip -oac copy -ovc copy -o output.avi -mf w=1920:h=1080:type=jpg:fps=15 'mf://<path>/*.jpg'
ffmpeg -y -i output.avi -r 25 -s 1920x1080 -vcodec libx264 -b:v 30000k output.mp4
I'm not a video guy (nor am I a camera guy, for that matter) and make no claim that this is the best way to make a time-lapse video.
Publish
Videos are build hourly, on the hour, while the sun is up and once more after nautical dusk.
After being build the video is pushed to a google bucket. This can take some time. After the new video has finished uploading any older videos from the same day are removed. Leaving only the last video of the day.
Any comments or questions: salishseacaminfo@gmail.com