Google Duo to be released within days

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

Erik Kay, engineering director at Google, introduces Allo and Duo on stage during the Google I/O 2016 developers conference in Mountain View, California May 18, 2016. REUTERS/Stephen Lam

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)