Today we are releasing Motion Stills, an iOS app from Google Research that acts as a virtual camera operator for your Apple Live Photos. We use our video stabilization technology to freeze the background into a still photo or create sweeping cinematic pans. The resulting looping GIFs and movies come alive, and can easily be shared via messaging or on social media.
|A Live Photo before and after stabilization with Motion Stills|
We pioneered this technology by stabilizing hundreds of millions of videos and creating GIF animations from photo bursts. Our algorithm uses linear programming to compute a virtual camera path that is optimized to recast videos and bursts as if they were filmed using stabilization equipment, yielding a still background or creating cinematic pans to remove shakiness.
Our challenge was to take technology designed to run distributed in a data center and shrink it down to run even faster on your mobile phone. We achieved a 40x speedup by using techniques such as temporal subsampling, decoupling of motion parameters, and using Google Research’s custom linear solver, GLOP. We obtain further speedup and conserve storage by computing low-resolution warp textures to perform real-time GPU rendering, just like in a videogame.
Short videos are perfect for creating loops, so we added loop optimization to bring out the best in your captures. Our approach identifies optimal start and end points, and also discards blurry frames. As an added benefit, this fixes “pocket shots” (footage of the phone being put back into the pocket).
To keep the background steady while looping, Motion Stills has to separate the background from the rest of the scene. This is a difficult task when foreground elements occlude significant portions of the video, as in the example below. Our novel method classifies motion vectors into foreground (red) and background (green) in a temporally consistent manner. We use a cascade of motion models, moving our motion estimation from simple to more complex models and biasing our results along the way.
|Left: Original with virtual camera path (red rectangle) and motion classification; foreground(red) vs. background(green) Right: Motion Stills result|
We’re excited to see what you can create with this app. From fun family moments to exciting adventures with friends, try it out and let us know what you think. Motion Stills is an on-device experience with no sign-in: even if you’re on top of a glacier without signal, you can see your results immediately. You can show us your favorite clips by using #motionstill on social media.
This app is a way for us to experiment and iterate quickly on the technology needed for short video creation. Based on the feedback we receive, we hope to integrate this feature into existing products like Google Photos.
Motion Stills is available on the App Store.