On Tue, Nov 17, 2015 at 10:03 AM, Chris Caudle <chris@chriscaudle.org> wrote:

On Mon, November 16, 2015 9:19 pm, jonetsu@teksavvy.com wrote:
> "You're probably asking Jack to handle midi devices, too, which
> doesn't work. Please deactivate MIDI in Jack's preferences and
> try again. We recommend using jack over alsa alone, as the
> performance and stability is way better when using jack."

Does the ALSA API allow one software to use the audio interface
exclusively, while also allowing a different application to use MIDI on
the same physical device?

ALSA considers PCM and MIDI devices on the same "card" to be entirely independent. So .... yes.

That is the only way I can see those instructions making sense, as saying
use JACK for audio, and access the ALSA MIDI directly from Bitwig.

Is that even possible, or once a device interface is claimed for exclusive
access by JACK does that mean both audio and MIDI access for that device
are locked to jackd?

If JACK (or any other app) uses ALSA RAW MIDI, then the device access is exclusive. ALSA Sequencer MIDI implies shared access.