Why is my iPhone Video Jittery?

After initially not having the best camera, Apple seem to have realised that people like to take pictures on their phones and with the latest versions introduced a really nice little camera with great optics. Certainly in a lot of situations I don’t bother with a ‘real’ camera and just use the phone. With the iPhone 4S the phone also has great video capabilities, taking really nice 1080p footage, and even allowing it to be edited on the phone with iMovie.

However there is one problem, some people won’t really notice it, but it is pretty apparent with certain sequences especially on a desktop. Take a look at this video of some steam trains:

The problem is apparent as the train comes slowly into the station, every so often there is a slight stall or jitter, more interestingly the problem doesn’t seem to appear watching the original footage on the phone. So what is going on?

The answer is actually pretty simple. We’re all used to being able to hold the iPhone any which way we like to take pictures. With the arrival of the volume button shutter functionality it encourages us to hold the phone with the volume buttons on the top, but in terms of the camera itself, this is actually holding the camera upside down.

With a photo this doesn’t much matter, but with a video it does.

If you watch the raw footage using certain low level video players like VLC you’ll find that the video is actually upside down. The iPhone makes use of a Quicktime feature to tell the video to play in a different orientation, and whilst the iPhone playback appears to have been optimised, desktop playback introduces this annoying jitter.

The answer then is pretty simple, until the same optimisation gets into desktop versions of Quicktime, you need to remember to hold the iPhone with the camera the right way up – the volume buttons should be at the bottom, and the home button on the right. The next video was taken with the same iPhone as the trains above, but, aside from my dodgy camerawork, the jitter is not apparent.

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