If a backend can be loaded, it does not mean that it can be used; e.g. weak-linked jack-backend if libjack is not available.
d991bb1 add 'available' interface to the AudioBackendInfo
libs/ardour/ardour/audio_backend.h | 8 ++++++++
libs/backends/alsa/alsa_audiobackend.cc | 8 ++++++++
libs/backends/dummy/dummy_audiobackend.cc | 8 ++++++++
libs/backends/jack/jack_api.cc | 8 ++++++++
libs/backends/wavesaudio/waves_audiobackend.cc | 8 ++++++++
libs/backends/wavesaudio/waves_audiobackend.h | 1 +
6 files changed, 41 insertions(+)