[LAU] Sysex with Jack MIDI

[Tim E. Real]

On 11/3/20 11:36 PM, Tim E. Real wrote:
> 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
> messages?"
>
> 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.
>
> Tim.
>
>
And... sorry, a couple of more points:

The test above was at 128 jack buffer size.


Also, a slightly embarrassing but relevant gory detail about MusE:

If latency correction is enabled (see Settings), be aware of a caveat:

It works great! But an unfinished detail means that the first brief

 �moment of audio or midi playback will NOT be heard.

This is because I will need to queue a small segment of playback

 �BEFORE the transport starts. That's not done yet.

It means if you press play and there is a sysex or any other event

 �placed right at that exact starting point, it will NOT be played.

Therefore, please place the red 'play head' cursor slightly BEFORE

 �the desired start point, say about one quarter bar or more,

 �before pressing play. All should be fine after that.


Thanks.

Tim.


>> 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.
>>>
>>>
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>>> Linux-audio-user at lists.linuxaudio.org
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>
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