[alsa-devel] MIDI Clock issue when aconnect multiple times to same device.
Hi All,
I have noticed an issue with the handling of MIDI clock when making multiple connections to and from the same device..
Specifically with EMAGIC AMT-8 and Unitor 8 Mk2 (I can't confirm it is happening for other devices).
The scenario is MIDI Port 1 is receiving MIDI clock along with note information for devices on ports 2 & 3 .. (in this scenario sending at 120 BPM) The MIDI clock signal is automatically distributed by the device to all other ports.
When connecting Input 1 to output 2 (to send MIDI from the first external device to the second).. The MIDI clock appears to be retransmitted a second time.. the device on port 2 then believes it is receiving a clock signal at approximately 168 BPM. This signal is not stable
When connecting input 1 to output 3 the MIDI clock seems to be distributed another time to the EMAGIC .. which is now sending out an even more unstable clock signal at approximate 189 BPM..
It is possible to filter physical inputs from receiving MIDI Clock or outputs from sending. This does not solve this issue (Filtering the input stops the clock altogether, filtering the output stops it from being received by the desired device)
However it is not possible to filter the messaging going to to the unit from a connection established with aconnect (or using tools like qjackctl).
I am not sure if it is possible to fix the driver for this issue,especially if the MIDI clock source is external. However, I thought it best to alert you to this situation.
thanks
Allan
participants (1)
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Allan Klinbail