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Send Midi Clock

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Jonas
Posts: 207
Reputable Member
Topic starter
 

I am thinking of adding a midi clock to my sequenser and found these messages.

clock (decimal 248, hex 0xF8)
start (decimal 250, hex 0xFA)
continue (decimal 251, hex 0xFB)
stop (decimal 252, hex 0xFC)

So is it enough to create a track and send 0xF8, 96 times per bar?
There is only one standard timing 24 for clock messages per quarter note?

In general these are just sent during playup and record?
Or maybe the clock is always running, and one just send a start to acknowledge one want slave gear to synch?
And stop to release synch?

I am not sure i understand continue in this context?

 
Posted : 25/05/2021 6:55 pm
Mike Kent
Posts: 86
Trusted Member
 

The MIDI 1.0 Detailed Specification (Document Version 4.2.1 Revised February 1996) has a pretty good description of the relationship between those messages. There are some details to be aware of that you can find in there. The section on Song Position Pointer is very helpful as well. Download the spec here: https://www.midi.org/specifications/midi1-specifications/m1-v4-2-1-midi-1-0-detailed-specification-96-1-4

Yes, you always send 24 per quarter note. You should send MIDI Clock messages nonstop. That way, any device that wants to synchronize can be better prepared to play at the correct tempo as soon as the Start command is sent. When a Stop command is sent, devices stop advancing immediately, but the clock continues to run in the background to keep the tempo at the ready and to keep devices synced even if there are tempo changes while stopped.

Mike.

Chair of MIDI 2.0 Working Group

 
Posted : 26/05/2021 1:53 am
Jonas
Posts: 207
Reputable Member
Topic starter
 

I tried to infuse just a start and clock signal into my sequenser, but my Roland SC-7 behaves strangely like it try to trigger notes on the clock?
Do anyone have a midi recorder/logger and tell me what is going wrong with the clock?

I could probably not tell what go wrong from the stream.

https://jonasth.github.io/debug/

 
Posted : 30/05/2021 3:36 am
Jonas
Posts: 207
Reputable Member
Topic starter
 

Maybe my polling of clock "5 ms" not tight enough to give a correct clock timing sent sent over port?

 
Posted : 30/05/2021 7:15 am
Jonas
Posts: 207
Reputable Member
Topic starter
 

Or have i got it all wrong and clock signal never sent with the actual midiplayup? It is just a separate synch thing sent over a separate cable?
I thought i could send it invoked with song, use it with a midichain setup synths and drummachine/recording device?

 
Posted : 30/05/2021 8:33 am
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