Even though they can’t actually display 4K videos, either through their own screens or accessories, Apple has enabled certain iOS devices to edit in 4K using the latest version of iMovie. So armed with an iPhone 6s Plus and two accessories, I decided to see whether the brand new iPad Pro was actually up to the task of editing and sharing 4K videos. The results were surprising, so if you’re wondering how 4K video editing actually works with Apple’s “Pro” tablet, read on…
What I Used
4K Video Camera: iPhone 6s Plus. Unlike most consumer 4K video cameras, the iPhone 6s and iPhone 6s Plus record 4K (3840×2160) videos in solely H.264 format rather than the newer H.265/HEVC standards. This makes iPhone 4K video files easy for various devices to open, but compromises on video quality and file size relative to H.265 videos. My 20-minute, 29-second iPhone 4K video required 7.7GB of storage space.
4K Video Editor: iPad Pro.The iPad Pro has been billed as a potential laptop replacement with processing power on par with Apple’s entry-level MacBook computers. Sold in 32GB or 128GB capacities, the 128GB version is much more likely to have enough free space for 4K video editing: remember, the only workspace you’ll have is what isn’t already occupied by apps, media files, and the original (unedited) 4K recordings, which can become large.
A Lightning to USB Camera Adapter.Originally released for the iPad (fourth-generation) and iPad mini, this adapter lets you connect various USB devices — including video cameras and cameras — to all iPad Air, iPad mini, and iPad Pro models to import videos and photos. It operates at USB 2.0 speeds.
What I Found
Recording 4K video with the iPhone 6s Plus was absolutely effortless. Default settings for both of the 6s models record video at 1080p (2K), but under Settings > Photos & Camera, you can choose to Record Video at “4K at 30 fps,” which activates 4K recording across all videos. At that point, it’s literally a matter of launching the Camera app — or 3D Touch-ing Camera to “Record Video” — and hitting the red record button… preferably when your iPhone is horizontal rather than vertical.
Sharing 4K video to the iPad Pro was not as easy as it should have been. Connecting the Lightning to USB Camera Adapter to the iPad Pro is simple, as is connecting the Lightning to USB Cable to both the iPhone and the Adapter. You’ll next need to “trust” authorize the iPad to share the iPhone’s files, after which you’ll be able to import videos (and photos) using the Photos app’s Import tab. Most likely due to an iOS bug, I found that the iPad Pro repeatedly requested trust authorizations from the iPhone, despite having previously been granted permission. Still, none of this is challenging — if it works.
In my testing with video clips, however, the import process didn’t work perfectly on the iPad Pro. A 1-minute, 46-second video clip came over without any problems in less than a minute, but after taking 6 minutes to supposedly import the 20-minute, 29-second clip, the video was nowhere to be found in the iPad’s library. A restart didn’t help, so I re-imported the clip, which properly showed up after an additional 7 minutes. As iFixit discovered in its iPad Pro teardown, the iPad Pro has the ability to support USB 3 transfer speeds and accessories, which could improve the import process — assuming Apple releases both a USB 3 Lightning adapter, a USB 3 Lightning cable, and (assuming the iPhone 6s doesn’t include support already), a device capable of sharing 4K content at USB 3 speeds.
Using iMovie to edit 4K video is pretty straightforward. You just need to select the 4K video clip, bring it into a project, and learn the appropriate (generally unmarked) finger gestures and icon taps to tweak the video to your heart’s content. If you can’t figure something out, a ? icon explains everything on screen and lets you access a deeper “Learn more” help system. I haven’t actively used iMovie for iOS in years, but within 10 minutes, I was able to merge my two clips together, add two photos, customize transitions, add a photo color filter and title the video.
Exporting 4K video from iMovie had the same type of hiccups I saw when importing the 4K videos to the iPad. I was able to do a 2K export of the video fairly quickly: it took only 7 minutes and 2.57GB to create a 22-minute, 25-second 1080p version of my clip, or around 1/3 realtime. That’s nice and fast — if you’re making short 2K videos, you’ll be done in a flash.
But the 4K export process stumbled. After 21 minutes of rendering, the iPad Pro stopped and said “An error occurred during export,” without providing any additional details. I then had to start again, and after around 45 minutes, the iPad Pro thankfully succeeded, creating a (surprisingly small, 4.15GB) 4K video. The 4K video rendering time would have been roughly 2 times the actual length of the video, except for the failed initial attempt, which brought the total rendering time to 3X realtime.
What I’d Change
The good news is that the iPad Pro can easily — though not flawlessly or quickly — be used to import and export 4K videos. If you’re only handling small videos, you’re less likely to bump into problems during importing, storage, or exporting. Depending on the type of “Pro” user you are, and the type of content you create, you might find the iPad Pro just fine for 4K editing work as-is.
However, many professionals would say that the iPad Pro’s efficacy as a 4K video editing tablet is currently limited by a variety of factors, ranging from storage capacity to software reliability when handling large 4K files, as well as import and export speeds. That’s even before you consider software/hardware limitations on handling raw H.265 videos created by non-iPhone video cameras, the current state of iPad Pro accessories, and the lack of 4K export quality controls. For serious video editing, it’s hard to recommend the iPad Pro right now over an entry-level MacBook Pro, which is similarly priced once you factor in the cost of Apple’s Smart Keyboard, yet much more capable. You don’t even need Apple’s Final Cut Pro to get a better editing experience on the Mac.
Improving the Pro’s editing performance is going to require at least some software and accessory changes, including an iOS update to improve transfer reliability, an iMovie update to enhance export reliability, and USB 3 cables to improve transfer speeds. Thinking more broadly, it wouldn’t be surprising to see Apple release a iPad Pro USB dock with enhanced connectivity options, enabling the tablet to come even closer to a laptop for storage, input, and video output when needed. I would love to see such a device, but shudder to think of the price Apple would charge for it. For now, the Lightning to USB Camera Adapter is a fine if not terribly fast option.