MIDI in the Software Studio

Once thought to be an endangered species, MIDI is making a major comeback thanks to software studios.

Created back in 1983 amid choruses of “it’s just a passing fancy,” MIDI looked like it was on the wane in the 90s, as hard disk recording became the main focus of recording. But with the advent of plug-in virtual instruments, MIDI has gained new life as the protocol used to trigger software synthesizers.

As a result, we’re in the unusual position of having MIDI be something new and different to people who weren’t even alive when it was born. So let’s investigate some of the most important highlights of this protocol, and how it relates to today’s recording world.

MIDI Inside the Computer

You may have heard complaints about MIDI being slow, and horror stories of MIDI delay. But this is true only when the computer is driving outboard MIDI gear through a MIDI interface, because MIDI is a serial protocol where a new piece of data gets transmitted every millisecond or so. Furthremore, the instrument or sound generator takes some time to react to this data. When a computer sends MIDI to an external sound module, the data has to exit through a port, be scanned by the keyboard, interpreted, and turned into a sound.

With virtual instruments, MIDI data flies around inside the computer and timing is extremely tight. With outboard gear, sending lots of controller data (more on this later) can “choke” the data stream; however, with native MIDI devices, it takes a lot to bog down a fast processor. Bottom line: If you need tight timing, native MIDI runs circles around outboard MIDI.

How Many voices Do You Really Need?

Playing back lots of voices from a soft synth puts a lot of demands on your CPU. As a result, look at the MIDI data stream and see if there are places where lots of notes are playing back at the same time.

This example shows a pad part; note how the red notes from held chords “hang on” past the onset of the next held chord. Even though each chord only plays four notes, during that transition eight notes are playing.

Trimming the ends of the notes, as shown with the blue notes in the example above, prevents this situation from happening — unless you’ve programmed a lengthy release time so that the note sounds even after you’ve let your fingers off the keys. In this case, consider using reverb or delay to extend the decay, so you can shorten the release time.

Preserving Tightness

However, even computers have limits — and running lots of virtual instruments can test those limits pretty quickly. Therefore, you still want to avoid stressing your computer unnecessarily. For example, use the lowest resolution needed. MIDI resolution is specified in PPQ (pulses per quarter note). Early MIDI devices had as little as 24 PPQ resolution, with computer-based sequencers opting for the then-extravagant resolutions of 96, 192, or 240 PPQ. As computers became more powerful, you started seeing PPQ specs at 960 and above.

But truthfully, you can set your computer to 192, 240, or 480 PPQ and get plenty of resolution without having to go to higher values, which would force your computer to do more calculations. I’d go so far as to say that even the most golden-ears types won’t be able to differentiate between a part recorded at 480 or 960 PQQ, especially because most musicians add some degree of quantization anyway (more on this later). Many programs won’t let you change PPQ, but check to see if yours does.

In Sonar, you can select a MIDI resolution from 48 to 960 PPQ. Here, 240 PPQ is being selected.

Also, don’t record extraneous data. MIDI sequencers have filters that let you exclude certain data types, like aftertouch, from being recorded. If you’re using a master keyboard with aftertouch to trigger a soft synth sound that responds to aftertouch, by all means, record the aftertouch data. Otherwise, filter it out because it takes up a lot of MIDI bandwidth.

More Natural Quantization

One of the early complaints about MIDI music was that it sounded sterile and mechanical. That’s not surprising, given that too many musicians went nuts with a sequencer’s quantization option, which shifts note attacks to the nearest specified rhythmic value (e.g., 8th note, 16th note, etc.). Real music doesn’t work that way; musicians tend to play around the beat a lot, not just on it.

However, most sequencers have a truly wonderful option called quantization strength. This moves notes closer to the specified rhythm by a percentage rather than creating a rhythmically perfect part. For example, if a note hits 6 milliseconds ahead of the beat and you quantize it to the beat with 50% strength, the note will end up 3 milliseconds ahead of the beat. This tightens up the rhythm without strangling it, which is a Good Thing.

In Magix Samplitude, go Options > MIDI Editor Options > Quantization Options to choose quantization strength.

Using Controllers for Greater Expressiveness

The powers behind MIDI recognized early on that just playing notes was b-o-r-i-n-g, and thus controller messages became part of the MIDI specification. Think about what happens when you play an acoustic instrument: There’s incredible complexity to the sound, whether it’s a vibrating string or a blown reed, that changes over time according to performance gestures. Hitting a string or a drum head harder doesn’t just make it louder, but often increases brightness and alters pitch slightly.

It’s possible to emulate these effects in a MIDI environment, but sometimes it takes a little work. For example, to better emulate a string or drum head sound as described above, you could tie filter cutoff and pitch to keyboard velocity so that hitting the keys harder opens up the filter somewhat and bends pitch up (by a very, very small amount). This is usually done by assigning velocity as a modulation source, specifying filter cutoff as a modulation destination, and determining how much of an influence the source has on the destination (usually a parameter called strength or amount).

The mark of a good synth programmer is someone who adds this sort of pointillistic level of detail, but this can be a time-consuming endeavor — which is why a lot of factory patches, developed over short periods of time in order to make a ship date, may not have all the tweaks you might want. So, tweak away and add variations that respond to velocity, aftertouch, mod wheel, foot controller, and the like — the resulting sound will be far more interesting and “alive.”

Getting Saved Via Sys Ex

If you do use outboard MIDI gear, you can almost certainly save its patch information via the use of system exclusive (sys ex) data. Furthermore, most MIDI sequencers can record this data, and even store it into a track and play it back automatically at the beginning of a song. Imagine that — you don’t need to save patches in your synth, use memory cards, or employ any other messy techniques. Just back up your data as part of your song.

If you’re going to record System Exclusive information, make sure it’s not being filtered out. Under Cubase SX’s Preferences, you can determine which MIDI messages will be filtered out of the MIDI data stream; here Poly Pressure and Aftertouch are being filtered out, but Sys Ex is enabled.

With longer sys ex messages or when saving to certain hosts, you may need to save the sys ex data as a separate bank, then send it manually to the outboard device. No big deal; it’s still pretty convenient.

MIDI and the Songwriting Connection

MIDI-driven tracks handle pitch transposition and tempo changes far better than digital audio ever can, because you’re just changing the data being fed to notes, not the timbral quality of the notes themselves. Granted, DSP-based pitch stretching is getting pretty clean, to the point where with small changes, you might not even notice any difference. But MIDI is still better.

As a result, consider using MIDI instruments when you’re writing a song and it first begins to take shape. You can experiment with different keys and tempos without having to re-record or stretch anything — just invoke the pitch transposition and tempo change options. After the song has settled down, you can then replace the MIDI scratch tracks with digital audio tracks from piano, guitar, etc. Then again, with virtual instruments sounding so good these days, maybe all you’ll really need to do is tweak the MIDI instrument tracks a bit.

In any event, if you missed MIDI the first time around, check it out. MIDI can be an integral, important element in any digital audio-oriented program.