[tt] U. Rochester: Music File Compressed 1, 000 Times Smaller than MP3

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U. Rochester: Music File Compressed 1,000 Times Smaller than MP3
http://www.rochester.edu/news/show.php?id=3136
8.4.1

Contact: Jonathan Sherwood
jonathan.sherwood at rochester.edu
585.273.4726


  20-Second Clarinet Solo Fits in a Single Kilobyte (And no, this is
                      not an April Fool's joke!)

Audio Files
(stored in .wav format for Web comparison)
   * Human performance recorded using MP3 format
http://www.rochester.edu/news/audio/Clar_orig.wav
   * Virtual performance using Bocko's new compression
http://www.rochester.edu/news/audio/Clar_synth.wav

Researchers at the University of Rochester have digitally reproduced
music in a file nearly 1,000 times smaller than a regular MP3 file.

The music, a 20-second clarinet solo, is encoded in less than a
single kilobyte, and is made possible by two innovations: recreating
in a computer both the real-world physics of a clarinet and the
physics of a clarinet player.

The achievement, announced today at the International Conference on
Acoustics Speech and Signal Processing held in Las Vegas, is not yet
a flawless reproduction of an original performance, but the
researchers say it's getting close.

"This is essentially a human-scale system of reproducing music,"
says Mark Bocko, professor of electrical and computer engineering
and co-creator of the technology. "Humans can manipulate their
tongue, breath, and fingers only so fast, so in theory we shouldn't
really have to measure the music many thousands of times a second
like we do on a CD. As a result, I think we may have found the
absolute least amount of data needed to reproduce a piece of music."

In replaying the music, a computer literally reproduces the original
performance based on everything it knows about clarinets and
clarinet playing. Two of Bocko's doctoral students, Xiaoxiao Dong
and Mark Sterling, worked with Bocko to measure every aspect of a
clarinet that affects its soundfrom the backpressure in the
mouthpiece for every different fingering, to the way sound radiates
from the instrument. They then built a computer model of the
clarinet, and the result is a virtual instrument built entirely from
the real-world acoustical measurements.

The team then set about creating a virtual player for the virtual
clarinet. They modeled how a clarinet player interacts with the
instrument including the fingerings, the force of breath, and the
pressure of the player's lips to determine how they would affect the
response of the virtual clarinet. Then, says Bocko, it's a matter of
letting the computer "listen" to a real clarinet performance to
infer and record the various actions required to create a specific
sound. The original sound is then reproduced by feeding the record
of the player's actions back into the computer model.

At present the results are a very close, though not yet a perfect,
representation of the original sound.

"We are still working on including 'tonguing,' or how the player
strikes the reed with the tongue to start notes in staccato
passages," says Bocko. "But in music with more sustained and
connected notes the method works quite well and it's difficult to
tell the synthesized sound from the original."

As the method is refined the researchers imagine that it may give
computer musicians more intuitive ways to create expressive music by
including the actions of a virtual musician in computer
synthesizers. And although the human vocal tract is highly complex,
Bocko says the method may in principle be extended to vocals as
well.

The current method handles only a single instrument at a time,
however in other work in the University's Music Research Lab with
post-doctoral researcher Gordana Velikic and Dave Headlam, professor
of music theory at the University of Rochester's Eastman School of
Music, the team has produced a method of separating multiple
instruments in a mix so the two methods can be combined to produce a
very compact recording.

Bocko believes that the quality will continue to improve as the
acoustic measurements and the resulting synthesis algorithms become
more accurate, and he says this process may represent the maximum
possible data compression of music.

"Maybe the future of music recording lies in reproducing performers
and not recording them," says Bocko.

This research is funded by the National Science Foundation.