RP 0.98-beta - Synchronization testing instructions

With the 0.98 release, Rack Performer can operate in various slave modes, in order to lock to an external master tempo or time reference.

We need all registered testers to try these new features and give us feedback, so we can validate them and fine-tune the synch engine parameters.

- If you select a transport control protocol but no synchro protocol, the application will operate in simple transport control mode.

Here's the subtlety: only those marked with an asterix are considered "position-lock protocols". You will need to select one of these to complete the tests.

- If you select a synchro protocol but no position-lock transport protocol, the application will operate in live synch mode.

- Finally if you select both a synchro protocol and a position-lock transport protocol, the application will operate in full slave mode.

When selecting a synchro protocol, 5 synch schemes are available. You will need to experiment with them all, depending on your setup and your tempo: some are very stable but also very slow to react when the tempo or rate is changed, while some are very fast but will also make samplers and loop stretchers flutter (if you use only synths you might not notice it)

Beware that changing the synch scheme while the synchro engine is engaged will disengage the locking. You might need to disable/enable power in RP and re-synch.

When using a timecode based protocol (MTC, MMC, MSC) make sure that the master timecode format and RP timecode format are the same.

To set the timecode format in RP use the "Live->Timecode format" menu.

In this mode, the transport controls (play, stop, reset and the location) are locked, and commands are received from the master. It can be used for instance to start and stop RP with an external recording machine.

The following commands (or their equivalent) must be tested: Play, Stop, Start/Reset, Locate.

The synch offset parameter in the transport bar (the knob and associated LCD) allows to compensate any positive or negative latency between the master and RP.

Note: this mode is free-running, meaning the master and RP will drift apart with time, unless you use the manual synch controls to compensate for that.

In this mode RP is completely slaved to the master and will follow exactly the master clock rate/tempo and position. This mode allows to use RP as a slave MIDI module in a MIDI setup.

Once again the synch offset parameter can be used to compensate any fixed latency difference, and in fact it is the only parameter you can set in this mode (but synch schemes are still available)

Note: RP must receive a start or reset message to engage its synch engine properly.

Finally, in live synch mode you can join any running master and lock synch, but to do that properly you will need to beat-match your sound like a DJ would do.

For that you will use either the tempo skew controls when using MIDI Clock protocol, or the rate skew controls when using MIDI Timecode protocol, and the Sync-To-Push control as well.

All these controls can be found on the transport bar. Hit Sync-to-Push when you hear the first downbeat of a bar (on the master) and it will locate RP while taking output latency into account. Then use the skew controls to push or slow down RP clock and properly align the phases.

When phase-aligned and locked, RP should stay in synch.

In order to test easily all the synch modes you will need to set up the MIDI metronome, in the Metronome configuration tab. Select any free MIDI channel for metronome output and apply.

Then add any VST instrument to your document and patch it properly. Enable power and enter Edit mode (Ctrl+4,Ctrl+2), then right-click on the VST instrument GUI (RP part of the wrapper) and select "Receive MIDI from->Single Channel->the channel you selected above" to make the module receive the metronome MIDI notes.

Finally display the Metronome floating window (Ctrl+Alt+T... T for time) and enable it.

When testing the synch locking you will need to have a close watch on your tempo in the transport bar (when using MIDI Clock protocol) or the rate bias parameter (when using MIDI Timecode) The latter can be displayed by clicking on the Tempo LCD and selecting "Nominal rate bias".

Some synch schemes with their current settings take a lot of time lock under certain setups or tempos, so you will need to experiment with them and see if there is any problem.