fix android application bug -- 2

i have Android call recorder app on the store, and need expert developer to fix one issue only which is: the recording sound quality is poor in some of devices especially on android 8, so when the app record a call the other side voice is very low or no sound can be heard, i need someone experienced in this field who can make the app record in very good quality, this may need c++ developer and implement good solution or may need some unique library, actually i am not sure what is the perfect solution. anyway its not just fine tuning needed. please anyone who is 100% sure that he can fix it can apply to this project, if you are not sure or you only want to make try please don't take this project because ill not pay him if i didn't got perfect results and it will be only a waste of time for me and him. ill mentioned down a reference app and want my app works in all devices like reference app do, this mean that ill test the result in multiple devices and if the sound quality is not same as the reference app (in term of sound quality) so ill not accept it, and please don't ask me to mention which devices not working fine with my app? (just make it like the reference app) which support a lot of devices on the market. reference app: [login to view URL]