[Dixielandjazz] Bringing dead piano greats up to scratch

[Bill Haesler]

Dear friends, 
This appeared this morning in the 'Next' (computer) section of today's
'Sydney Morning Herald".
A bit long, but the last paragraph may be of interest, particularly to list
mate, John Farrell.
Kind regards,
Bill. 
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Bringing dead piano greats up to scratch
By Mick Hamer
May 10, 2005
Next

The month music lovers in Raleigh, North Carolina, will be able to hear in
concert two of the greatest pianists of the 20th century, both of whom are
long dead.

Zenph Studios, a Raleigh-based software company, has found a way to take a
music recording and convert it into a live concert played on real
instruments. It will be a faithful rendition of the original pianists' work.

Zenph resurrected a scratchy mono recording of Bach's Goldberg Variations,
made by the Canadian pianist Glenn Gould in 1955, and a recording of a
Chopin (below) prelude by Alfred Cortot in 1928. Cortot died in 1962, Gould
in 1982.

The breakthrough is to extract the sounds from audio recordings and convert
them into a high-resolution version of MIDI, the standard way of coding
music for computers. To do so they had to tackle the problem of polyphonic
transcription - distinguishing several notes played simultaneously.

Researchers have been trying for years to achieve this, but previous
attempts have managed to identify at best 80-90 per cent of notes correctly
- with about 10 per cent missing and another 10 per cent wrong.

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Zenph says it has found a way to do this, although for commercial reasons it
won't release details. But the company is confident enough to have organised
the concert, at which a Disklavier Pro piano, one of a handful of concert
grands that can record and play back high-definition MIDI files, will replay
Gould's and Cortot's work. The piano will replicate every note, down to the
velocity of the hammer and position of the key when it was played.

"We have only begun seeing excellent results in the past few weeks," says
John Walker, president of Zenph Studios. "The results are note perfect."

Mr Walker has an impressive history: before founding Zenph in 2002, he was a
leading developer of VoIP, which allows phone calls to be carried on the
internet.

He says the precise timing of notes is almost as important as identifying
the correct notes. One of Zenph's final checks is to play back the
conversion on the Disklavier and to make an audio recording of it. The
engineers then play back a stereo version of the music: one channel has the
original recording, the other has the recording of the conversion. "If
they're different by even a few milliseconds, the ear immediately identifies
that something's wrong - there's a slight echo effect," Mr Walker says.

Resurrected pieces include a scratchy recording of Bach's Goldberg
Variations and a recording of a Chopin prelude.

"The project at Zenph is definitely very, very interesting," says Anssi
Klapuri, of the Tampere University of Technology, Finland, who is one of the
world's leading experts on polyphonic transcription.

The company is now working on a recording made at a private party by the
jazz giant Art Tatum two years before his death in 1956. There are many
recordings that have never been released because of some flaw, such as
background noise or an out-of-tune piano. Zenph hopes that companies will
use the technology to make recordings from this type of material, or to
clean up noisy recordings.

- New Scientist
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