Logic: send only start/stop (no midi clock)

Hi everyone,

Is it possible to send only start stop messages via midi to external gear, but without sending clock?

thanks!

I don’t understand the context. If a device is in MIDI external sync mode, so it responds to incoming MIDI start/stop messages, without any clock messages, it’s just going to be be stuck forever waiting for the next tick, so it won’t do anything. If you want the device to be in internal sync, it will probably ignore all MIDI system real-time messages.

You’ll need to check the behaviour of whatever device you are using and it’s sync options, but I don’t really understand the goal here…

From the MIDI 1.0 spec:

Start. Start the current sequence playing. (This message will be followed with Timing Clocks).

This is not from the spec, but rather an article describing the expected behavior based on the spec:

The master needs to be able to start the slave precisely when the master starts. The master does this by sending a MIDI Start message. The MIDI Start message alerts the slave that, upon receipt of the very next MIDI Clock message, the slave should start the playback of its sequence. In other words, the MIDI Start puts the slave in "play mode", and the receipt of that first MIDI Clock marks the initial downbeat of the song (ie, MIDI Beat 0). What this means is that (typically) the master sends out that MIDI Clock "downbeat" immediately after the MIDI Start. (In practice, most masters allow a 1 millisecond interval inbetween the MIDI Start and subsequent MIDI Clock messages in order to give the slave an opportunity to prepare itself for playback).

This is why des99 wrote that responding to MIDI start but ignoring MIDI clock doesn't make any sense.

You could try inserting a meta event 47 - “send byte” on the channel with a value of 0xFA (start) 0xFC (stop)

I can’t test it right now so let us know if it works

The send byte meta appears to only allow values up to 127, but the logic documentation indicates you can input values up to 255 decimal...

Is this a bug possibly ? can someone verify

From the manual:

Num = 47 (Send Byte to MIDI): This sends the track instrument any byte value (Val) between 0 and 255 ($00-$FF). For example, if you send 246 as the byte, this is equivalent to a MIDI tuning request message. The display shows Send Byte $F6. Use this meta event only if you know what you’re doing—if you don’t, your sound modules and synths may start to behave very oddly.

In LPX, the Send Byte meta event does indeed cap out at 127 in the event list - unlike Logic Pro 7.x, where you can enter values up to 255 (I just checked).

So I'd vote this is a bug or unintended behaviour in LPX that differs to the documentation, and is worth reporting.

thanks, sounds complicated. the device I'm trying to get to start / stop with logic is the elektron octatrack.

I prefer to have the octatrack as the main clock/brain. but I'd like to be able to record it (and alle the connected synths) in sync with logic (by setting logic to the same tempo as I set the octatrack, and hitting record in logic, and have the octatrack start playing when I hit record in Logic).

I prefer to have the octatrack as the main clock/brain.

Why? It normally makes the most sense to have the device that needs the highest accuracy (ie sample accurate) to be the master. If you want Logic to slave to this, the Octratrack would need to be able to output MTC, not MIDI clock. What's the need to have the Octatrack as the master device?

but I'd like to be able to record it (and alle the connected synths) in sync with logic (by setting logic to the same tempo as I set the octatrack, and hitting record in logic, and have the octatrack start playing when I hit record in Logic).

Setting two devices to the same tempo is not "in sync", and it will drift and it's a bad way to do this. You can of course record the Octatrak in Logic, and all your connected synths, but really, you should make Logic the master, and actually sync the other clocked devices from it, unless there is a specific reason not to do this (which I'm unaware of).

Otherwise you're just making things hard for yourself!

On 9/29/2021 at 11:14 AM, TendingTropic said:

the device I'm trying to get to start / stop with logic is the elektron octatrack

Did you ever figure this out? I'm trying to do the same thing with an Analog Four. I have it listening to clock, but I want to use the "send midi byte" function to start and stop the A4 at certain sections in the project. 

nope, ended up using logic as midi clock master as recommended!