How to start midi - Android (Xamarin - C#))

[Fumetsujo]

Good day,

I try to play a sound on my android device, through an Xamarin C# application (build version focussed on Android 8.1).

Unfortunately when I start the app to play the piano sound I get "Error: sequence contains no elements".

This is my (slim) code:

                var access = MidiAccessManager.Default;
                var output = access.OpenOutputAsync(access.Outputs.Last().Id).Result;  
                output.Send(new byte[] { 0xC0, GeneralMidi.Instruments.AcousticGrandPiano }, 0, 2, 0);   
                output.CloseAsync();

I believe the error comes from " var output = access.OpenOutputAsync(access.Outputs.Last().Id).Result; "

I have no idea how to generate a midi port id (if this would be the root of the problem).

Can you help me to play a piano note?

Thank you very much in advance.

[Atsushi Eno]

I often write such a hacky sample, but Last() will throw that typical Linq exception if there is no such item in the sequence (IEnumerable, here access.Outputs).

You need a working MIDI device in Android MIDI API manner, which is either USB MIDI device, BLE MIDI device, or MidiDeviceService. https://developer.android.com/reference/android/media/midi/package-summary

The same kind of situation (i.e. lack of MIDI devices) happens to macOS too.

[Fumetsujo]

Thank you for your quick response!

I'll try it out.

[Atsushi Eno]

Feel free to ask questions here, but I will close this issue so far. Thanks.