When we were in the Bahamas I tried my hand at some time-lapse video using my little Nikon S50 camera in movie mode. The results were pretty good, but I found myself battling the twin hurdles of battery life and patience (as well as lack of a tripod.) The result was a shorter-than-desired video clip that went by far too quickly.
Then a couple of weeks ago I read a good blog post on the Digital Urban blog with simple instructions on doing time-lapse photography with a webcam. While Digital Urban’s instructions look great, and I want to try those out, it occurred to me that there might be an even easier way to accomplish this – use someone else’s webcam! Here’s one that I created very quickly using some simple software and the webcam for Table Rock State Park…
All you need for this project is a computer (duh) that no one will need to use for a few hours, a good steady Internet connection, a website with an embedded webcam image, and the BSR Screen Recorder. Other screen recorder programs will probably work, but I like the BSR program because it’s very easy to set the record rate, and that is the lynch pin in this method.
There are tons of sites out there with suitable webcams. Sciway.net has a page listing the webcams for South Carolina, including SCDOT webcams, several colleges, a couple of cities, and parks. Some of these will work great for time-lapse, and others, not so much. Just visit a few to see which ones you like. There are similar cams all over the world, so there are tons of possibilities. First make sure that screen savers and sleep mode are disabled, then load up your chosen site.
The next step is to determine the refresh rate of your chosen webcam. Usually there will be a little label or something that says “This view refreshes every 30 seconds” or something like that. Sometimes you can figure it out by seeing how often the image changes. If neither of those work, you might try viewing the page source by going to File-View-Source in Internet Explorer, or View-Page Source in Firefox. You’ll see a bunch of HTML code and other stuff, but press CTRL-F and search for either “refresh” or “reload”. You might find something like this…
Sometimes there is a comment line like the one at the first arrow. Sometimes there is just a number, in this case “30000”. Don’t worry about any conversions to seconds or anything like that. Just remember the first two digits of the number – in this case 30. That will do.
Close the page view window and open up the BSR software. A setup wizard will let you select a region of the screen. Select the portion of your screen that contains the cam image. Once you have done this DON’T SCROLL!
In the screen capture above, the red line indicates the capture area. If you scroll the red box remains still while the image moves.
If the wizard doesn’t give you a prompt to set the capture rate, you can click on the Config button, then on the video tab.
In the image above the yellow arrow points to the Video Speed section. You want to set this so that it captures 1 frame every 30 seconds, because that’s the refresh rate of the webcam. If the webcam refreshed every minute, you would set the capture rate accordingly. Make sure that “Playback Speed of AVI” and “Play one frame in every X seconds” are unchecked.
Once this is all set up, click the red record button and walk away. Seriously. This is where the patience comes in. In order to have any decent video you will need to leave this running for multiple hours. It might even be a good idea to turn the monitor off while you’re gone. In the case of my Table Rock video, I started it right before I left for work, then stopped the recording when I got home in the evening.
Once you’re finished recording BSR saves the file as a preliminary AVI file and brings up a video editing mode. This has some nice features, such as doing text overlays, etc. When it comes time to produce the final video file you can set the final frame rate for the video. You want to set this to 30 frames per second, which is the standard for good quality video. 30 frames per second and a refresh rate of 30 seconds are purely coincidental in this case. Always use 30 fps when you produce the final video, regardless of the original webcam screen refresh rate.
…and tha’s all there really is to it. Your final video should be a good time-lapse movie from your scene.
As I mentioned previously, some webcams work better than others. A cam with a good clear view of the sky will show cloud movement, which can be nice. Also, urban scenes with moving traffic give a great sense of activity in time lapse. Basically, you don’t want something that’s going to be unchanging during the amount of time you are recording. If the webcam appears to be real-time live video, you may still want to set the capture rate at 30 seconds or so, other-wise the end result won’t look time-lapse.
One last word. The BSR software I used here is the free trial version, the BSR logo can be seen in all four corners of my video. To remove that will cost about $40. The software with the editing suite sells for $90.