I'm using xamarin.android to create an android application. for working on the output of recorded audios in android for changing its pitch and the other thing with NWaves package, I need to change its format to .wav. I tried to use many audio convertors but all of them threw exceptions, but it should work with FFmpeg. However, I used this code but it doesn't generate any file.

List<string> cmd = new List<string>();
        cmd.Add("ffmpeg");
        cmd.Add("-i");
        cmd.Add("/storage/emulated/0/Android/data/com.companyname.pushersvc/demo.3GP");
        cmd.Add("/storage/emulated/0/Android/data/com.companyname.pushersvc/test.wav");


        string cmdParams = string.Join(" ", cmd);

        await FFMpeg.Xamarin.FFMpegLibrary.Run(
            Application.Context,
            cmdParams
            );
        return new FileInfo(path);

I read this and FFMpeg docs, but all of them used .mp4 convertor. I also read ffmpeg doc for audio converting which you can see the code, which is not working