[LAD] Jack MTC/MMC slaving

Paul Davis paul at linuxaudiosystems.com
Mon Nov 24 17:52:49 UTC 2008

On Mon, 2008-11-24 at 18:36 +0100, Ralf Mardorf wrote:

> I'm not familiar with MMC and I'm less familiar with Linux MIDI, because
> of to much troubles, but I know that I need to sync an Atari ST with
> Linux MIDI by MTC and this isn't possible for all applications. It would
> be good if JACK transport can be master and slave for song position
> pointer and also timing clock.

MIDI SPP and MIDI Clock are unrelated to MMC.

it is not possible to interpet either of them without tempo/meter
information - they do not refer to an audio-based timeline, only a
"musical time" (bars|beats|ticks).

>  ALSA MIDI is more important than JACK MIDI.

they are not divided from each other. JACK MIDI is a cleaner API and
allows much simpler sharing of MIDI data between audio applications. the
fact that few apps directly support it at present isn't very significant
since you can bridge from ALSA to JACK MIDI and back again.

that said, i do think its a little odd to make this utility connect to
JACK MIDI. any JACK MIDI client sending MMC to do transport control is
just being stupid - it can control the transport directly. the
interesting cases all involve the MMC source outside the computer, which
makes using ALSA MIDI directly a bit more sensible (IMHO).


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