Google will release its cross-platform, one-to-one video calling app Duo "in the next few days".

The app - which can be used on Android or iOS devices - pits Google directly against Apple's FaceTime, which allows video calls only between Apple devices.
Duo will also compete with Skype, Facebook's Messenger and even its own Hangout app.
Google said in a blog post that Duo comes with a unique feature called "knock knock", which lets the recipient see live video of the caller before answering.
Google said video calls would work even on slower networks by "gracefully" reducing the resolution to keep the call going smoothly.
"For video calls on the go, Duo will switch between wi-fi and cellular data automatically without dropping your call," Google principal software engineer Justin Uberti said.
Google, owned by Alphabet, said the app would be live worldwide within days.
(Reporting by Supantha Mukherjee in Bengaluru; Editing by Savio D'Souza)