That's sort of like my initial approach to cooking: if a couple spices are good, then throwing in a whole bunch of spices must make something that tastes terrific! It didn't take many experiments to prove that approach wrong.

Similarly, my first attempts at orchestral writing consisted of trying to get every instrument to do something different. The result was as predictably bad as my attempts at randomly combining foodstuff: a huge mess.

For the most part, BiaB arrangements work because the various instruments (drums, bass, guitar) play supporting roles. As long as they follow the same beat and feel, they'll mesh together well.

Put a lead instrument on top of that, and it'll generally sit pretty well. But add another instrument, and you won't end up with a duet. Sure, it might mesh nicely at points, but that's purely chance. Adding more instruments to the mix will only ensure that things get worse, not better.

Listen to some orchestral music, and - despite the initial complexity - you'll find that most music can be broken down into the following general functions: melody, counter-melody, harmony, and bass.

More than one instrument will often be assigned to a particular part - for example, you might have the strings taking the melody in octaves, or the brass playing the counter-melody in block chords, and so on. But that's homophony - a thickened line, with all the instruments are playing the same rhythm, moving in similar directions. (BiaB's harmony function is an excellent example of this).

So there may be 52 instruments playing, but they aren't all playing something different - even if they aren't all playing the same note.

And often, many of these instruments aren't doing anything at all. Good orchestration is based on variety. So the woodwinds will have the melody for a few bars, and then it'll be handed off to the strings, and so on.

And that's ignoring the problem of coordinating all these parts. Consider, for example, what it takes to create a counter-melody. You'll want the counter-melody to:
  • Use chordal notes, but not notes already selected by the melody;
  • Generally move in the opposite direction of the melody;
  • Avoid dissonant intervals;
  • Avoid parallel fifths and octaves;
  • Be sparse when the melody is busy, and busy when the melody is sparse
If you don't follow those rules, your counter-melody is going to sound pretty stupid. This sort of capability is beyond RealTracks at the moment, and it ignores another huge constraint:
  • Make the choice from the pre-recorded options


Anyway, the short(er) answer is that although it may seem that an orchestra is a lot of instruments playing different things, when you break it down, it's a lot of instruments playing similar things, following lots of complex rules that if you don't follow, you'll end up with a mess.

-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?