The D6503 is expected to make its debut at MWC later this month and is expected to feature a 5.2 inch Triluminos display, with a refreshed Xperia UI, Snapdragon 800 processor, 3GB of RAM and 16GB of native storage on board. The 20.7MP rear camera plays video in 4K and takes 1080p video at 60fps.
Some lucky guy with a prototype of the device has leaked some screenshots showing the 4K video app, the Timeshift Video app and the Creative Effect camera app. The good news is that these features are expected to be included with the Android 4.4.2 update for the Sony Xperia Z1, Sony Xperia Z1 Compact and Sony Xperia Z Ultra. Speaking of Android 4.4.2, the D6503 is expected to include this build of the OS right out of the box.
Thanks, Anonymous Tipster!