I’ve previously blogged about how I sometimes setup a webcam to take pictures and turn them into videos. I thought I’d update that here with something new I’ve done, fully automated time lapse videos on Ubuntu. Here’s when I came up with:-
(apologies for the terrible music, I added that from a pre-defined set of options on YouTube)
(I quite like the cloud that pops into existence at ~27 seconds in)
Over the next few weeks there’s an Air Show where I live and the skies fill with all manner of strange aircraft. I’m usually working so I don’t always see them as they fly over, but usually hear them! I wanted a way to capture the skies above my house and make it easily available for me to view later.
So my requirements were basically this:-
- Take pictures at fairly high frequency – one per second – the planes are sometimes quick!
- Turn all the pictures into a time lapse video – possibly at one hour intervals
- Upload the videos somewhere online (YouTube) so I can view them from anywhere later
- Delete all the pictures so I don’t run out of disk space
- Automate it all
Taking the picture
I’ve already covered this really, but for this job I have tweaked the .webcamrc file to take a picture every second, only save images locally & not to upload them. Here’s the basics of my .webcamrc:-
[ftp] dir = /home/alan/Pictures/webcam/current file = webcam.jpg tmp = uploading.jpeg debug = 1 local = 1 [grab] device = /dev/video0 text = popeycam %Y-%m-%d %H:%M:%S fg_red = 255 fg_green = 0 fg_blue = 0 width = 1280 height = 720 delay = 1 brightness = 50 rotate = 0 top = 0 left = 0 bottom = -1 right = -1 quality = 100 once = 0 archive = /home/alan/Pictures/webcam/archive/%Y/%m/%d/%H/snap%Y-%m-%d-%H-%M-%S.jpg
Key things to note, “delay = 1” gives us an image every second. The archive directory is where the images will be stored, in sub-folders for easy management and later deletion. That’s it, put that in the home directory of the user taking pictures and then run webcam. Watch your disk space get eaten up.
Making the video
This is pretty straightforward and can be done in various ways. I chose to do two-pass x264 encoding with mencoder. In this snippet we take the images from one hour – in this case midnight to 1AM on 2nd July 2014 – from /home/alan/Pictures/webcam/archive/2014/07/02/00 and make a video in /home/alan/Pictures/webcam/2014070200.avi and a final output in /home/alan/Videos/webcam/2014070200.avi which is the one I upload.
mencoder "mf:///home/alan/Pictures/webcam/archive/2014/07/02/00/*.jpg" -mf fps=60 -o /home/alan/Pictures/webcam/2014070200.avi -ovc x264 -x264encopts direct=auto:pass=1:turbo:bitrate=9600:bframes=1:me=umh:partitions=all:trellis=1:qp_step=4:qcomp=0.7:direct_pred=auto:keyint=300 -vf scale=-1:-10,harddup mencoder "mf:///home/alan/Pictures/webcam/archive/2014/07/02/00/*.jpg" -mf fps=60 -o /home/alan/Pictures/webcam/2014070200.avi -ovc x264 -x264encopts direct=auto:pass=2:bitrate=9600:frameref=5:bframes=1:me=umh:partitions=all:trellis=1:qp_step=4:qcomp=0.7:direct_pred=auto:keyint=300 -vf scale=-1:-10,harddup -o /home/alan/Videos/webcam/2014070200.avi
Upload videos to YouTube
The project youtube-upload came in handy here. It’s pretty simple with a bunch of command line parameters – most of which should be pretty obvious – to upload to youtube from the command line. Here’s a snippet with some credentials redacted.
python youtube_upload/youtube_upload.py --email=########## --password=########## --private --title="2014070200" --description="Time lapse of Farnborough sky at 00 on 02 07 2014" --category="Entertainment" --keywords="timelapse" /home/alan/Videos/webcam/2014070200.avi
I have set the videos all to be private for now, because I don’t want to spam any subscriber with a boring video of clouds every hour. If I find an interesting one I can make it public. I did consider making a second channel, but the youtube-upload script (or rather the YouTube API) doesn’t seem to support specifying a different channel from the default one. So I’d have to switch to a different channel by default work around this, and then make them all public by default, maybe.
In addition YouTube sends me a “Well done Alan” patronising email whenever a video is upload, so I know when it breaks, I stop getting those mails.
Delete the pictures
This is easy, I just rm the /home/alan/Pictures/webcam/archive/2014/07/02/00 directory once the upload is done. I don’t bother to check if the video uploaded okay first because if it fails to upload I still want to delete the pictures, or my disk will fill up. I already have the videos archived, so can upload those later if the script breaks.
Automate it all
webcam is running constantly in a ‘screen’ window, that part is easy. I could detect when it dies and re-spawn it maybe. It has been known to crash now and then. I’ll get to that when that happens 😉
I created a cron job which runs at 10 mins past the hour, and collects all the images from the previous hour.
10 * * * * /home/alan/bin/encode_upload.sh
I learned the useful “1 hour ago” option to the GNU date command. This lets me pick up the images from the previous hour and deals with all the silly calculation to figure out what the previous hour was.
Here (on github) is the final script. Don’t laugh.