In iOS 8, Apple added a new feature to the built-in Camera app: Time-lapse. The announcement at WWDC earlier this year brought an initial wave of panic to Tom and I. As the makers of a stop motion and time-lapse app (Frameographer), we thought we had just been sherlocked. Fortunately, this doesn't seem to be the case, as the time-lapse mode Apple introduced lacks any features or options. Which raises the question: how does the time-lapse mode actually work?

In the Camera app, Time-lapse is a new mode you can toggle to (it's located furthest to the left on the mode selector). Aside from the focus and exposure options available in all modes in the Camera app, Time-lapse mode just has a single button, to start and stop a time-lapse. As such, everything about the time-lapse you are creating is completely obfuscated. How many frames per second are being captured? How fast is the video being sped up relative to real time? What is the framerate of the resulting video? These questions demand answers!

On Apple's website, they claim that in time-lapse mode, "iOS 8 does all the work, snapping photos at dynamically selected intervals." When I first read this, I thought they were doing something super fancy, like monitoring the frame for movement and only snapping a picture when something changes. On deeper reflection, this would be a bad idea. Time-lapse videos look best when they are buttery smooth, and dynamically selecting intervals in this fashion would create a jittery and jerky video. So what does Apple mean by "dynamically selected intervals"?

Turns out, what Apple is doing is quite simple, and indeed, pretty clever. I ran several tests, shooting time-lapse videos for various durations. You can view a spreadsheet of all the tests I ran here.

What Apple means by "dynamically selected intervals" is they are doubling the speed of the time-lapse and taking half as many pictures per second as the recording duration doubles. Sounds complex, but it's actually very simple.

Recording Duration Frame Capture Rate Speed Relative to Real Time
Less than 10 minutes 2 frames every second 15x
10 minutes to 20 minutes 1 frame every second 30x
20 minutes to 40 minutes 1 frame every 2 seconds 60x
40 minutes to 1 hour 20 minutes 1 frame every 4 seconds 120x
1 hour 20 minutes to 2 hours 40 minutes 1 frame every 8 seconds 240x


This is an efficient way to assemble a time-lapse. When you start recording a time-lapse, the app only captures 2 frames per second. If the recording period extends beyond 10 minutes, the app switches to capturing only 1 frame per second, and deletes every other frame it had captured in the first 10 minutes. When the recording duration doubles (20 minutes), the same thing happens. Now the app is only capturing 1 frame every 2 seconds, and previous frames are dropped to match this tempo. And so forth. The longest video I recorded was 8 hours, but presumably using this method you could record for much longer (Apple's website casually mentions 30 hours). Because the app is being so efficient with frame capture and storage, you don't need to worry about your phone capacity filling up. 

The result of this method is that anything you shoot will generally end up being between 20 and 40 seconds long, an ideal shareable length. Also worth mentioning, the resulting video is always 30 fps, the standard framerate for video. No surprises there.

I found a nice lookout in Austin with my Glif, new iPhone 6, and tripod, to shoot some examples.


This video was recorded for 5 minutes in time-lapse mode. The resulting video is 20 seconds long at 30 fps. 


This video was recorded for 40 minutes in time-lapse mode. The resulting video is also 20 seconds long at 30 fps, but it is 8 times faster than the 5 minute video, and 120 times faster than real time. Note the speed of the clouds for the most obvious difference. I also shot videos at 10 minutes and 20 minutes. All of the videos were shot on an iPhone 6, and are unedited.

So, when would you use the Time-lapse mode in the built-in Camera app, as opposed to Hyperlapse or Frameographer? In true Apple fashion, the Time-lapse mode is dead simple, with no options to mess with. Hyperlapse, however, is also dead simple, and features the incredible video stabilization. It's a great choice for quick and casual time-lapses, or for when the camera is not stabilized on a tripod. If you are making a less casual time-lapse that will take half an hour or more to record, I would definitely recommend something like Frameographer in lieu of the built in Time-lapse feature. I am biased, obviously, but I am of the opinion that if you are putting that much time into the creation of your time-lapse, you should have some say over the final output. Apps like Frameographer allow you to adjust the speed and framerate after all the frames are shot.

That said, we are thrilled Apple has decided to include Time-lapse as a new camera mode, as it will hopefully introduce many people to how fun and easy it is to make time-lapses.

 


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