Convert AVAudioRecorder output to OPUS audio file

In my app I have to convert an audio recording into the OPUS format. The file has to be playable on numerous devices and OPUS is the only possibility for this case. Attached you will find the original MP3 file as well as the file that I obtain from [login to view URL] The final file should be similar to what one can obtain from said website. What I need from you is a working project that converts the recording from AVAudioRecorder to OPUS in a similar way the website does it. Other headers etc. may work too but I will have to check the result first. There are libraries such as libopus which may help you with this, the code eventually has to work on watchOS which shouldn’t make a difference as the libraries are written in C. By default, the AVAudioRecorder converts it into a CAFF container which is not compatible to e.g. some Android devices. That's why I need OPUS. Maybe there is even a way to do it from the AVAudioRecorder directly, that would also work for me. If you take this offer and are able to implement it, you can send me the conversion result so I will check whether it is compatible to our platform and once I have checked whether the code can run on the watchOS simulator as well as the actual watchOS device without issues implementing and uploading it, I will release the payment.