A remarkable concert in Raleigh, North Carolina, this Thursday, May 19, will feature Glenn Gould performing excerpts from Bach’s Goldberg Variations, and the great French pianist Alfred Cortot playing a Chopin Prelude, on a nine-foot Yamaha grand piano.
What’s remarkable about it is that Gould died in 1982 and Cortot in 1962. But the performances aren’t recordings; rather, they’re recreations of performances given by Gould in 1955 and Cortot in 1928, intended to showcase a new technology that promises to bring many great piano performances of the last century or so, trapped in the purgatory of bad recordings, back to life.
The Yamaha Grand Disklavier Pro, is the modern equivalent of a player piano; but its mechanism, rather than being a vacuum-driven mechanical affair controlled by a perforated paper roll, is a computer-driven electromechanical affair controlled by a MIDI file.
MIDI (Musical Instrument Digital Interface) was created by synthesizer manufacturers in the 1980s so that electronic instruments could talk to each other. MIDI files contain all the information an electronic instrument needs to play music: which instrument to emulate, what notes to play, how long to play them, how fast to play them, how loud to play them, etc. In fact, using MIDI to control a piano is overkill: unlike a synthesizer, a piano doesn’t have to choose what instrument it’s going to sound like. The only things a pianist, from the lowliest amateur to the greatest concert player, have control over are which notes he plays, how fast he plays them, how long he holds them, and how loud they are.
Yamaha recognized the possibilities early on, and the MIDI-driven Disklavier pianos were the result. Playing on such a piano, a pianist can turn his performance into a MIDI file that other Disklaviers can then play back note-perfect. (In an interesting side note, there are even ways of turning old player-piano rolls into MIDI files so they, too, can be played on a Disklavier.)
Now Zenph Studios, a Raleigh-based software company, has developed a method of extracting the sounds from audio recordings of piano performances and converting them into a high-resolution MIDI file (Yamaha’s high-resolution MIDI conveys 10 times as much information as regular MIDI, to capture more subtleties of performance).
Others attempts to turn audio recordings into MIDI files over the years have always stumbled on the same challenge: how to accurately recognize and transcribe polyphonic passages, when several different notes are being played simultaneously. Past efforts have never managed to capture more than 80 to 90 percent of the polyphonic notes, leaving as many as 20 percent either missing, or flat- (or, I guess, sharp-) out wrong.
For business reasons, Zenph won’t explain how it has managed to solve this problem, but the company says it’s now getting note-perfect results.
Just as important to a pianist’s performance as correct notes, however, is the duration assigned to them. It’s in the subtle pushing and pulling of the tempo that interpretation resides. Zenph promises amazing fidelity there, too: one of the company’s final checks is to make a new audio recording of the Disklavier performance, then play that recording back on a stereo system in which the new recording comes out of one speaker and the original recording out of the other. If the two recordings are even slightly different, the ear will hear an echo effect.
Zenph is pressing ahead with other old recordings: its next project is a recording made at a private party by jazz great Art Tatum two years before his death in 1956, which has never been released because of background noise. There are many, many similar recordings, with flaws ranging from audience chatter to an out-of-tune piano, and others that were made on primitive equipment that produced low-quality mono sound. The software that transcribes the original piece into MIDI ignores any non-piano sounds in a recording, and, with MIDI, it’s a simple matter to correct out-of-tune notes—so that in some cases, the re-created performances may well be superior to the original.
Zenph hopes recording companies will use this technique to clean up old recordings and to make new, sparkling ones of performances never released before. Even performances recorded off the radio or on cheap cassette recorders could be recovered and made good as new.
Who knows? Maybe live performances by dead pianists will soon become commonplace.
It would be a great gimmick for a Hallowe’en symphony concert!
