Hi guys,
I am planning to start the support of MIDI BLE profile[1]. This profile is not officially supported yet, but it will most likely be very similar, so development efforts are still valid.
I suggest two main goals: * To be transparent to applications, i.e., use rawmidi and sequencer ALSA interfaces to interact. * To support peripheral and central BLE roles.
My question is: what is the best way possible of doing it?
My initial though is to write a GATT BlueZ profile plugin that will load snd-virtmidi module with id and midi_devs parameters, then read and write seq events from/to it. I am not sure if this is really possible.
Another way of implementing is as a rawmidi and a seq plugin using the BlueZ GATT D-Bus interface. IMO this is not ideal because it requires a lot more work (rawmidi and seq plugins, maybe even a library to avoid code duplication) and has an overhead of using dbus.
It is also possible to write a kernel module to handle ALSA card/device setup and reads and writes from the bluez plugin (perhaps this simplifies things because it has less dependencies).
They all have the problem of context switching between bluez plugin and alsa midi driver. I would prefer to use a shared ring buffer between ALSA e BlueZ.
Any ideas and comments?
[1] https://developer.apple.com/bluetooth/Apple-Bluetooth-Low-Energy-MIDI-Specif...
PS: I am at #bluez and #alsa as ftonello.
Felipe Tonello