Synchronization to MIDI Clock

ReWire users – read this!

This section is about synchronization via MIDI Clock, and does not apply to users of ReWire. If you are using Reason together with a ReWire compatible application, ReWire automatically handles all synchronization issues for you. See “About synchronization” for details.

What is synchronization and MIDI Clock?

Synchronization, in this context, is when you make Reason play at the same tempo as another MIDI device; where both start, stop and can locate to certain positions, together. This is done by transmitting MIDI Clock signals between Reason and the other device. MIDI Clock is a very fast “metronome” that can be transmitted in a MIDI cable. As part of the MIDI Clock concept there are also instructions for Start, Stop and locating to sixteenth note positions.

You can set up synchronization between Reason and hardware devices (tape recorders, drum machines, stand alone sequencers, workstations etc.) and other computer programs running on the same or on another computer.

Host/Device

In a synchronized system there is always one Host and one or more Devices. In our case, the host is the one that controls the tempo. In other words, it is only the tempo setting on the host that is of any relevance, since the devices follow the host's tempo.

•	Reason can act as Host or Device. That is, Reason can transmit MIDI Clock signals and also receive them.

Using Reason as MIDI Clock Host

Reason can transmit standard MIDI Clock signal. It also sends Start, Stop, Continue and Song Position Pointer (SPP) MIDI messages so that you can also control the transport functions of the synced equipment from the Transport Panel in Reason. To set up Reason as a MIDI Clock host, proceed as follows:

1.	Select the desired MIDI Port from the Output drop-down menu in the “MIDI clock sync” section on the Sync tab in Preferences.

Selecting MIDI clock output port.

2.	Close the Preferences window.

3.	Select “Sync -> Send MIDI Clock” from the Options menu:

Alternatively, click the Send Clock button in the Sync Mode section on the Transport panel:

Now, you have set up Reason as a MIDI Clock sync master. When you start the Reason sequencer, MIDI Clock is sent out on the selected MIDI Out Port.

If your synced MIDI equipment is not in phase with the Reason sequencer, you might have to change the Output Offset in the “MIDI clock sync” section on the Sync tab in Preferences.

If the external MIDI equipment lags, set the Output Offset to a negative value.

A negative Output Offset means that the MIDI Clock signal is sent out from Reason earlier to compensate for the lag.

If the external MIDI equipment plays ahead of the Reason sequencer, set the Output Offset to a positive value.

There are also some additional options regarding the MIDI Clock signal that can be selected at the bottom of the MIDI clock sync section:

•	Send MIDI clock while sequencer is stopped.

When this box is checked, Reason continues to send out MIDI clock signal also when the sequencer is stopped.

•	Send song position pointer.

When this box is checked, Reason sends out MIDI Song Position Pointer information to the device. If the synced device doesn't support Song Position Pointer, turning this setting off can improve synchronization. This is also useful if the synced device is playing a looped pattern and should disregard all positioning.

•	Send stop/continue when repositioning.

When this box is checked Reason sends out Stop/Song Position Pointer/Continue messages to the synced device, if the song position locator in the sequencer is moved (either manually or when in Loop mode) when the sequencer is running.

If unchecked, only Song Position Pointer messages are sent out if the song position locator is moved (or in Loop mode) while the sequencer is running.

Syncing Reason to an external MIDI application or instrument

This example assumes that you have an external device, such as a drum machine, hardware sequencer, another computer, tape recorder etc., that transmits MIDI Clock signals to which you want to synchronize Reason.

1.	Connect the device via USB/MIDI to the computer running Reason.

2.	Set up the host so that it transmits MIDI Clock signals to the MIDI Out you just connected to the computer running Reason.

3.	In Reason, pull down the Edit menu (under Mac OS X, the Reason menu) and open the Preferences dialog. Click the Sync tab.

4.	Pull down the MIDI Clock Input pop-up and select the MIDI Input to which you connected the host.

5.	Close the dialog.

6.	Activate MIDI Clock Sync from the Options menu - “Sync” submenu in Reason.

7.	Activate playback on the host.

Reason will start playing in sync with it.

If the Reason sequencer lags or plays ahead of the host, adjust the Input Offset on the Sync page in Preferences, see “Adjusting for Latency”.

Syncing Reason to another program on the same computer

The preferred method for synchronizing two applications is by using ReWire, see “ReWire”. However, if the application you need to sync Reason to doesn’t support ReWire, you can try the procedures described below.

This section describes how to use MIDI Clock to synchronize Reason to another application running on the same computer.

Note that synchronization via MIDI Clock makes the two programs play at the same time, that is, they both “run” when you “hit play”. It does not mean they can both play audio at the same time.

Proceed as follows:

1.	Set up the host, so that it transmits MIDI Clock to Reason:

Under Windows this is done by selecting one of the MIDI routing utility ports.

2.	In Reason, open the Preferences - Sync page.

3.	Pull down the MIDI Clock Input pop-up and select the corresponding MIDI port.

4.	Close the dialog.

5.	Activate MIDI Clock Sync from the Options menu - “Sync” submenu in Reason.

6.	Activate playback on the host.

Reason will start playing in sync with it.

If the Reason sequencer lags or plays ahead of the host adjust the Input Offset on the Sync page in Preferences, see “Adjusting for Latency”.

External synchronization considerations

Adjusting for Latency

Because of the MIDI latency problem described in “ReWire and Latency”, you might need to adjust Reason’s playback in relation to the sync host, so that they are in perfect time. The tempo will not differ between the two, but Reason might play ahead or behind the other application. You might need to adjust this. However, this is something you only need to do once. The setting is stored with your other preferences, so you don’t need to adjust it again.

Proceed as follows:

1.	Set up the other application so that it generates a solid click, on for example quarter or eighth notes, preferably with a special sound on the downbeat.

This click can either come from an internal metronome or from a MIDI source. If you use a MIDI source, make sure you pick one that has solid MIDI timing.

2.	Set up Reason so that it plays a similar rhythm as the other application.

You might for example use the sequencer Click or a Redrum drum computer for this.

3.	Start the two applications in sync.

4.	Make sure you hear both applications at approximately equal level.

5.	Open the Preferences dialog in Reason and click the Sync tab.

6.	Trim the “Input Offset” setting until the “clicks” from the both sources sound at exactly the same time.

7.	Close the Preferences dialog in Reason.

If Latency Compensation isn’t enough

There might be situations where you can’t compensate enough in Reason to make two software applications run in sync. This might especially be true if the other application is an audio sequencer, that is if it can record and playback both audio and MIDI.

This problem is an indication of the fact that the other application has not been set up properly and that its audio playback is not in sync with its own MIDI playback.

This is not something that you can or should compensate for in Reason. Instead, follow the instruction included with the other application to make sure its MIDI playback and audio playback are correctly locked to each other.

About the beginning of the Song

Due to the latency phenomenon, described in “About latency”, Reason needs some time to correct its playback speed when it first receives the Start command. This can be noted as a small glitch in the audio playback, when the program starts. If this is a problem, you need to insert a couple of empty measures at the beginning of the Song. Proceed as follows:

1.	Set the Left Locator to “1. 1. 1.0” and the right Locator to “3. 1. 1.0“.

2.	Click somewhere in the main sequencer area to move the menu focus to the sequencer.

3.	Select “Insert Bars Between Locators” from the Edit menu.

4.	Set up the other device/application, so that it also plays two empty bars at the beginning.

About MIDI Song Position Pointers

MIDI Clock actually consists of five type of messages: The actual clock (the metronome that establishes the tempo), Start, Stop and Continue commands and Song Position Pointers. This last type of message contains information about positions, so that a program for example “knows” where in a Song to start playback from.

Normally, this ensures that you can locate to any position and activate playback from there. In older devices, Song Position Pointers might not be implemented. This means that you will be able to synchronize properly only if you start both devices from the absolute beginning of the song.

About Tempo and Tempo Changes

Again, due to the latency phenomenon, Reason needs a bit of time to adjust to changes in tempo. If there are abrupt changes in the MIDI Clock, due to drastic tempo changes in the master, you will note that Reason will require up to one measure to adjust itself to the change. How long this actually takes also depends on the precision of the incoming MIDI Clock. The more precise it is, the faster Reason can adjust to it.

If this adjustment is a problem, try to use gradual tempo changes rather than immediate ones.

When Reason is synchronized to external MIDI Clock, there is no Tempo readout.

Note that high-quality stretching of audio tracks is automatically disabled when syncing from external MIDI Clock.

Input Focus and Play Focus

If you activate (external) MIDI Clock sync on the Options|Sync menu, the Transport Panel controls will be disabled, and Reason will not run unless MIDI Sync data is provided from an external device.

The Input Focus (MIDI + Audio) and Play Focus (MIDI Sync) buttons (located on the Reason Hardware Interface) relate to how incoming MIDI and MIDI sync should be handled if there are several open Song documents. If you have two or more Songs opened, and no MIDI sync is used, the currently selected Song (the document “on top”) always has Input focus.

If (external) MIDI Clock sync is enabled (which is global for all currently open Song documents), this functionality changes in the following way:

•	If both “Play Focus” and “Input Focus” are activated for a Song, incoming MIDI data, MIDI sync (and Audio) will be sent to this Song, regardless of whether another Song is currently in focus.

•	If only “Input Focus” is activated for Song, and another Song has “Play Focus”, incoming MIDI (and Audio) will be sent to the former and MIDI sync to the latter (i.e this Song will play back), regardless of which Song is currently in focus.