[LAU] Sysex with Jack MIDI

Tim E. Real termtech at rogers.com
Wed Nov 4 05:36:06 CET 2020

On 11/3/20 11:31 PM, Tim E. Real wrote:
> Tested MusE with Jack 1.9.14:
> Successfully sent a 1536 byte sysex from one MusE instance to another.
> Has Jack midi sysex length finally improved? Yay!
> It sure didn't seem to be working years ago when I did the MusE sysex 
> stuff.
> Thanks.
> Tim.
> MusE sequencer project.

"Bonus question: is it possible to be warned when jack is dropping sysex

I forgot to mention, in MusE we call jack_midi_event_reserve(),

 �and if it fails, look for this message:

"MidiJackDevice::queueEvent ME_SYSEX: buffer overflow, sysex too big, 
event lost"

I did not see the message in the test above. IIRC years ago it would happen.


> On 11/2/20 6:25 PM, Alexandre DENIS wrote:
>> Hi,
>> I try to understand why sysex go through jack MIDI sometimes, and
>> sometimes they are lost. I am aware that jack has a limit for the
>> maximum message size per period, but I am playing with program dump of
>> my Nordlead which are only 139 bytes -- definitely not huge.
>> I am running jackdbus with a2jmidid, through Catia. My system is Debian
>> + kxstudio.
>> When I try an application with native jack MIDI, such as Reaper (with
>> jack backend) or MuSE, I can record sysex successfully, but when I play
>> it, it never reaches the hardware.
>> With applications using ALSA sequencer (tested with qtractor and
>> Rosegarden), I can record and play successfully sysex using ALSA.
>> However, I cannot record nor play sysex when connecting jack MIDI ports
>> instead (jack MIDI wrapper ports from a2jmidid).
>> Is this the expected behavior? Are we stuck with ALSA when we are
>> dealing with sysex messages?
>> Bonus question: is it possible to be warned when jack is dropping sysex
>> messages?
>> Thanks!
>> -a.
>> _______________________________________________
>> Linux-audio-user mailing list
>> Linux-audio-user at lists.linuxaudio.org
>> https://lists.linuxaudio.org/listinfo/linux-audio-user
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