Hello,
I understand you are finding a person who will help you add a feature to an existing software. I have been working with C/C++ and Qt for a long time (see my profile for projects I have done on freelancer.com). I can help you with this, in additional, I know music, sound processing and graphic programming as I'm a game programmer. I hope we will have a discussion about this project soon. Thank you very much!
Best regards,
Binh