ReWire is a software-based technology that lets you share application resources inside your computer—as long as those resources are ReWire-compatible. The ReWire technology was jointly developed by Propellerhead Software and Steinberg, so most products sold by either company are compatible with this technology. In addition, a large number of third-party developers have made their applications ReWire-compatible. This chapter looks at some setup tips when working with ReWire applications in a Cubase project.
Here’s a summary of what you will learn in this chapter:
How to use Cubase as a ReWire host
How to set up a ReWire channel in a project
How to use ReWire and VSTi (VST instrument) channels in the Mixer
How to export ReWire tracks as audio files
ReWire’s functionality is really quite simple and quite useful: It patches the outputs of one software application into the inputs of another software application and synchronizes their Transport controls. This has some similarities to using a VSTi, except that ReWire instruments or ReWire software applications are not running inside Cubase, as a VSTi is—it’s a cross-application technology.
Active ReWire channels appear as additional channels in Cubase’s Mixer. This enables all ReWire-compatible applications to share the same audio hardware, assigning each ReWire instrument a different output if you want and also providing a common Transport control and timing base; you can control playback for all applications from Cubase.
In other words, to use ReWire, you need to have ReWire-compatible applications installed on your system. Available ReWire applications appear at the bottom of Cubase’s Devices menu once installed.
Each application can offer a large number of channels; for example, ReWire 2.0–compatible applications support up to 256 channels. For a given project, however, you will enable only the specific number of channels you want to stream between applications. That’s because each active ReWire channel imposes an additional load on your system, and you want to keep the load to a minimum to improve system performance. Once a channel is enabled, a corresponding ReWire channel appears in Cubase’s Mixer. You can always enable additional ReWire channels in your project later if needed.
The order in which you launch ReWire applications is important because the first ReWire application will be considered the ReWire host. Each subsequent ReWire application you launch will run in ReWire slave mode. The audio properties and tempo settings of slaved applications will conform to the host’s properties and settings. If you change the tempo in the slave application, Cubase will turn its tempo track off to follow this new tempo. In other words, to keep any tempo changes accurate in both applications, it’s better to use the tempo track in Cubase to change tempos.
At this point, the Transport bars in both applications are linked. This means that you can start and stop playback within any ReWire-compatible application, and the others will follow. If you record events, they are recorded in the application that is active—in other words, the recording takes place in the application where you clicked the Record button. So, recording in each application is independent, but playback follows.
If you use cycle playback or recording, all applications follow this loop. And, as the ReWire host, Cubase always controls the tempo setting when the Tempo track is active. If you change the tempo in Cubase’s Tempo track, the other applications follow its lead. If you are not using the Tempo track, you can change the manual tempo setting in either application, and the playback reflects it. When you start playback at 100 BPM in Live and the Tempo track in Cubase is not enabled to control the project tempo, both applications play at 100 BPM.
All ReWire channels that are not muted when you export your mix-down using the File > Export > Audio mix-down option are included in the output file.
When the ReWired application uses MIDI to trigger software instruments, you may need to create a MIDI track in Cubase and select the ReWire-compatible MIDI output port as its output. This will send the MIDI events from this Cubase track to the ReWire application in order for it to generate the sounds that will appear in the ReWire audio channel you have configured inside Cubase for the output from that ReWire application. On the other hand, if the ReWire-compatible application is strictly audio-based, using audio loops or events on tracks of its own, simply activating the bus to which the audio is routed inside Cubase will do. For example, if you have audio tracks in a ReWire application that are coming out through its Main Mix bus, activating this bus inside Cubase will cause any audio routed to that application’s Main Mix to be sent (rerouted) into the Cubase Mixer’s ReWire channel.
You saw in Chapter 10 that you can use a VST instrument either by loading it as you create an instrument track, or by loading the VSTi in the VST Instruments panel and then selecting this VSTi as the output destination for one or more MIDI tracks. With ReWire 2.0 applications, a MIDI track can be routed through a ReWired MIDI output port. This enables you to send MIDI events from Cubase to a software instrument loaded in the ReWired application. Once the ReWired instrument receives the signal, you then need to route the audio output back to Cubase by enabling that channel, as described earlier in this chapter.
For the most part, audio channels representing audio tracks or the audio output from a VSTi or ReWire instrument are fairly similar. There are, however, some notable differences:
You can’t assign an audio input bus to an instrument, VSTi, or ReWire audio channel.
There are no Record Enable buttons on these audio channels. Instrument channels do have a Record Enable button that will record MIDI events, but not audio.
There is no Monitor button because there are no audio inputs to monitor. On instrument channels, the Monitor button lets you monitor or play MIDI events without having to record-enable the track. This is convenient when you simply want to play through the instrument while recording something else on another track.
Below the Bypass Send Effect button on VSTi and instrument tracks is the Edit VST Instrument button that opens the VSTi interface for changing settings in the instrument. In contrast, because ReWire instruments are not inside Cubase, you need to access their host application to make changes to their settings.
VSTi and ReWire channels have a separate button in the Mixer’s Common panel on the left, allowing you to hide all instances of either type of channel from view.
In the Mixer, there are distinct background colors behind the volume faders on Instrument and VSTi channels, ReWire channels, and audio channels.
Because VSTi and ReWire channels are audio channels within Cubase’s Mixer, they will be included in the audio mix-down when the File > Export > Audio Mixdown function is used. Make sure these tracks are unmuted if you want to include them in the exported audio file for your mix-down.
VSTi and ReWire devices can eat up resources from your computer; exporting those tracks as audio files might also let you unload them from memory to add more real-time inserts or FX channels. If this is what you need to do, always save your project with a different name to keep access to the original MIDI-based tracks and synth settings in the project.
Obviously, you should repeat these steps for each ReWire channel you need to export. When you are finished exporting channels, you can unload the ReWire application from your computer’s memory. Delete all corresponding MIDI tracks, or even better, place them inside a folder track in case you want to try playing the same MIDI events through a different instrument later. You should then save this new copy of your project file with a different name. This keeps your original file intact in case you need to go back and re-edit the ReWire tracks; you can then use this “lighter” version of the project for the mixing process.
For instrument tracks you can use the Freeze Instrument Channel functionality, which offers a number of convenient resource optimization options. You will find more on the freeze options in Chapter 40, “Optimizing Your Project.”