App for iPhone and android

I need an iPhone/iPad app. I would like it designed and built. I want a game/app made for iPhone and android. The app I want would enable users to have rap cyphers via FaceTime where they can choos any instrumental /link on YouTube and both parties would hear the same sound on both phones/headphones/earphones. the app would allow users to freestyle while on video chat while the song is playing. Also with a record option.. as for as backgrounds and app images you could use a like a cartoon rapper with a mic or just a staged with a dim light on the mic. I definitely want the app's niche to be that users can video "chat/rap) with there friends using any link on YouTube chosen by user who initiated the session.(By Contacting the other user via the app" I want users to sign up/sign in where they choose a username which other users can see when they use the global option where they can see who all are online on a earth 3D type map wheee all the online users glow bluish while offline users don't appear on the globe.