[LAD] Jack MTC/MMC slaving

Rui Nuno Capela rncbc at rncbc.org
Mon Nov 24 22:33:12 UTC 2008

Paul Davis wrote:
> On Mon, 2008-11-24 at 21:40 +0100, Ralf Mardorf wrote:
>> Alex Montgomery wrote:
>>>     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).
>>> Wow, really? I thought that JACK (via ALSA on Linux, but this is
>>> implementation dependent) supported access to external ports anyway.
>>> We were going to switch to JACK midi because it is theoretically more
>>> portable (to OS X, say) and more JACK compliant (which a JACK
>>> transport app should be), without adding any dependencies (obviously
>>> we are already using the JACK libraries since jackctlmmc is a JACK
>>> client.).  I assumed that the only repercussion of switching to JACK
>>> midi would be that the user would have to make the connection to the
>>> external ports using a JACK controller instead of alsa utilities like
>>> aconnect. In the case of people using an app like QJackctl, the
>>> application would simply hop to the JACK tab instead of the ALSA tab.
>>> Is that not true? Are there other complications that could stop users
>>> from connecting to external midi devices?
>>> It's good news if ALSA is the better choice; it's how the code is
>>> currently written anyway.
>>> -- Alex
>> The jackd -dalsa -X option seems to make clients available for both
>> QjackCtl tabs, but e.g. Qtractor's connection GUI only shows ALSA.

qtractor doesn't know about jack-midi.  all midi stuff is done through
alsa-seq. the MIDI tab in qtractor connections widget is indeed
identical to qjackctl's ALSA tab.

> Not relevant, because using Qtractor as the MMC source is silly :)

otoh, maybe silly because qtractor is also fully mmc and jack-transport
aware. iow, qtractor and jackmmcctl will probably step on each other
toes. hmmm...

rncbc aka Rui Nuno Capela
rncbc at rncbc.org

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