Write an iPhone application

Dear friends, I want you to help me creating a task. The task is simple like this: Record a video and an audio file (play from AVAudioPlayer) TOGETHER. When user finishes recording video, I have a final file with video and that audio mixed. Actually it like you record karaoke singing yourself, audio is beat music. When user finish singing, they have final product (sing video and beat music mixed). Remember you need to mix audio realtime (so user don't need to wait after singing), not after user finish record video, then you insert the audio If you think you can do, please give me a demo app, (I will provide UDID of my iphone). Then you send me source code, I send you the payment. Please type "abelhoang" when submit proposal, so I can know you read this completely. Thank you very much!