Interestingly, both programs are installed using the Windows Add New Hardware function. It makes sense when you consider that the operating system regards them as hardware devices. What may not make sense as quickly is that whatever data enters the “cable’s” Output port gets sent to its Input port. If that seems backward to you, you’re in good company. But if you compare virtual MIDI cables to a real hardware setup, in which data flows out of a controller to the input of a synth, it becomes clearer.
In other words, choose Hubi’s as the destination on one or more tracks in your sequencer (the “controller”), and Hubi’s takes over the role of controller. Hubi’s Output port, which is receiving the data from your sequencer, will then send that data to whatever is connected to its Input port, which will be your soft synth or drum machine. Simple, right? Hubi’s supports 4 loopback ports; MIDI Yoke offers 16. Both support multiple inputs and outputs to each port.
However, as in the Gamma9000 example, you’re only halfway there at this point. To hear the output of your soft device, you may need a second sound card, a multichannel sound card, or a virtual audio cable, such as the appropriately named Virtual Audio Cable from Ntonyx. Offering as many as 64 multiclient cables with resolution as high as 32 bits, Virtual Audio Cable installs and operates much like Hubi’s Loopback Device, but it has a couple of quirks worth noting.
First, the demo version uses a fixed interrupt period that, on my system, resulted in a significant amount of clicking in the audio stream. The full version lets you adjust the interrupt period, which should result in smoother performance. Second, Virtual Audio Cable requires a helper application so you can monitor the audio output. When I connected the audio output of VAZ Modular into Cakewalk Pro Audio using Virtual Audio Cable, I was able to record but not monitor the sound. A tiny applet called Audio Repeater is included with the Virtual Audio Cable distribution file. It allows you to monitor the signal while recording.
To put it all together, here’s what’s happening: the output of a Pro Audio MIDI track is assigned to Hubi’s Loopback Device, which carries the data into VAZ Modular and triggers the selected synthesizer. The audio output of VAZ Modular is sent through Virtual Audio Cable simultaneously to Pro Audio for recording and to Audio Repeater for monitoring through the audio interface. As before, think of each element as a hardware device; you’d wire it exactly the same way and expect the same results.
Wrapping Cables
Virtual cables have a number of other uses. MIDI Yoke can route its output to a related program called MIDI-OX that allows you to filter or remap MIDI data. You can also combine the two to provide multiclient functionality to your hardware MIDI inputs and outputs. Dozens of shareware MIDI utilities available for PCs let you do things such as analyze the output of a MIDI control surface routed through a virtual cable, so you can adapt it for use with unsupported programs. If your favorite editor/librarian isn’t tightly integrated with your sequencer, a virtual cable lets you connect the two to record your edits as SysEx data.
Although plug-in technology continues to simplify the interconnection of MIDI and audio software, virtual cables still have a place in a desktop studio. Whether you use an interconnection standard, an interapplication bus, or a shareware cable program, the principles are the same. Follow the same logic as with physical connections, and it should all come together.