jack_umidi - jack_midi_event_get() failed, lost MIDI event

[Hans Petter Selasky]

On 11/11/18 8:11 AM, Clemens Ladisch wrote:
> Marcel Bonnet wrote:> Hello.
>> I wrote a program to send System Exclusive Messages to my Roland XP-30
>> Keyboard. This program (QStage) connects to jack_umidi .
>> I send  a burst of 4296 events every time I load a sysex file.
>>
>> My program does not print "NOTE LOST", so I suppose that "maybe" I am using
>> the API correctly. But jack_umidi is zombiffied DPRINTing hundreds times
>> the same error  only after I load the second or third sysexfile (even if
>> its the same file).
>>
>> "umidi_write:160: jack_midi_event_get() failed, lost MIDI event."
> 
> What timestamps (sample offsets) are you using?
> 
> Jack is all about sample-accurate event timing, so I suspect that events
> get lost because they cannot be transmitted at what Jack thinks is the
> desired time.
> 
>> I started jackd with a Midi BufSize > 4296 * 4 bytes
> 
> If you take care that events are not queued faster than they can be
> transmitted (about 3125 bytes/s), the buffer size should not matter.
> 

Did you try putting a delay between every of those MIDU sysex events. 
I'm afraid that somewhere along the road JACK MIDI will overflow.

Or group them like 10 MIDI events and then a 10 ms pause.

--HPS