快猫短视频

THIS October, fresh recordings by the great Russian pianist and composer
Sergei Rachmaninoff shot into Billboard magazine鈥檚 top ten. It was a
curious turn of events. The recordings were made in a hall just outside Los
Angeles earlier this year, yet Rachmaninoff has been dead for more than 50
years.

The key to Rachmaninoff鈥檚 ghostly comeback is a computer-controlled piano and
a series of binary recordings that the pianist made between 1919 and 1929. His
performances were recorded as holes punched in piano rolls, which resembled
rolls of fax paper and served as the floppy discs of the time. The new recording
is the work of Wayne Stahnke, a Los Angeles inventor who is central to the
development of computer-controlled pianos. He took the piano rolls, scanned the
pattern of holes into his computer, and converted the resulting image into data
that can be read by the Bosendorfer SE, the computer-controlled piano he
designed. It was this machine that brought Rachmaninoff back to life this
year.

Rachmaninoff is now available for repeat performances. But don鈥檛 expect to
hear him play a Bosendorfer SE鈥攐nly 33 were ever made and Stahnke owns two
of them. But Stahnke has also converted the performances into files that can be
played on Yamaha鈥檚 more widely available Disklavier. He鈥檚 even posted a sample
of the conversions on the Web. So if you want to hear Rachmaninoff play an
extract from Rimsky-Korsakov鈥檚 Flight of the Bumble Bee, all you have
to do is to download it onto a floppy disc and put it in the nearest
Disklavier.

In an age when pop CDs positively throb with digital sounds鈥攅verything
from electronic drums to oral excitation and sampled passages stolen from past
hits鈥攑layer pianos may seem horribly old-fashioned. Yet the advent of a
thing called the musical instrument digital interface, better known as Midi, has
opened the way to a new generation of advanced player pianos, such as Disklavier
and Bosendorfer SE, that are half computer, half acoustic instrument.

Midi is a standard for digital music, which emerged in 1981 after an
agreement between the major manufacturers of electronic instruments, including
Roland and Yamaha. Today, virtually all electronic keyboards, along with many
other instruments and the soundcard in your computer, can produce a Midi file
and play it back. A Midi file is essentially an electronic version of what is
recorded on a piano roll, and includes such basic information as when a note
should be sounded and how long it should last.

Many of the world鈥檚 leading pianists have recorded for the new player pianos,
including Chick Corea and Dick Hyman, who directed the music for several Woody
Allen films. But why not listen to these musicians on CD? Part of the reason is
that, even with the best recording techniques, no CD can match the perfect high
fidelity of a piano. 鈥淢y interest has always been in real piano music,鈥� says
Stahnke.

Player pianos are also great teachers. A piano鈥檚 keys are just levers that
seesaw about a fulcrum. While a human pushes them down at the front,
computer-controlled pianos have a row of solenoids at the rear that push the
keys up. So when a midi file plays, phantom fingers appear to fly over the keys.
For an aspiring pianist it鈥檚 like a master class with the hero of your choice.
You can even slow the music down to follow the fingers through a difficult
passage until you have perfected it. In the 1920s and 1930s, Fats Waller and a
host of other pianists learnt to play in just this way鈥攖hough, of course,
they had to rely on piano rolls rather than floppy discs.

The idea of recording a pianist and then playing back the performance on a
piano goes back to about 1903, when a German piano maker, Edwin Welte, invented
a system for recording rolls. Many of Europe鈥檚 leading soloists of the time
recorded for Welte, including the French composer Maurice Ravel. Within a few
years Welte鈥檚 idea had spread to the US.

Left to their own devices, most player pianos play back just the notes on a
piano roll at a constant volume. But there were a variety of very sophisticated
machines at the top end of the market. Rachmaninoff made all his recordings for
the American Piano Company, which marketed the 鈥渞eproducing piano鈥濃�攁n
instrument that the company claimed could reproduce every nuance of a
performance, including the dynamic range. Ampico had an active research
laboratory, which devoted considerable effort to perfecting its pianos and
improving recording techniques.

These early machines worked by suction. As a piano roll unwinds, it passes
over a brass 鈥渢racker bar鈥�, which has a row of holes cut into it. Each hole is
connected via a collection of pipes and valves to a suction pump. Normally the
paper roll stops air entering the plumbing through the tracker bar, but when a
hole in the paper coincides with a hole in the bar, the inflow of air operates a
pneumatic valve that plays a note, or operates some other function of the
instrument, such as a pedal.

In its most widely found form, the Ampico piano divided the keyboard into
two鈥攔oughly corresponding to the left and right hands. It had a three-bit
coding system for dynamics, which allowed each half of the keyboard to be set at
seven different volume levels by increasing or reducing the strength of the
suction. These levels were in steps of roughly 3 decibels, giving the piano a
dynamic range that varied from the whisper of pianissimo to a loud fortissimo. A
mechanism allowed the machine to slide from one volume to another, so it could
reproduce a crescendo. The volume could also be changed rapidly, so the piano
could accent notes and pick out a melody. But unlike modern computer-controlled
pianos, the machine could only play鈥攏ot record.

To make his recordings, Rachmaninoff used a recording piano in Ampico鈥檚 New
York studio. Each key was linked to a stylus poised over the moving paper of a
master roll. When a key was played, the corresponding stylus marked a line on
the roll that continued until the key was released. After the recording, a
technician took the master roll of paper and punched holes in it where there
were marks.

This process recorded only the notes. The dynamics were mostly added by
editors, who listened to the recording session and marked which passages were
soft and loud on a musical score. The technician used this information to punch
holes that controlled the dynamics. It was all a bit subjective.

Various companies claimed to have automatic systems that recorded dynamics,
but they seem to have been largely a figment of their public relations. The only
documented system, from the Ampico company, made its debut in 1926 (Journal
of the Acoustical Society of America, vol 1, p 138). The people at Ampico
realised that the volume of any note depends solely on the speed of the hammer
as it hits the string. If it strikes at high speed, the note is loud; low speed
gives a soft sound. Ampico鈥檚 recording piano had a silver wire embedded in each
of its hammer shanks
(see Diagram).
As the hammer headed towards its
string, the wire brushed against two electrical contacts in turn, producing a
signal that the recording mechanism translated into marks on a second, moving
roll of paper. The size of the marks depended on the speed of the hammers.
Technicians later married up these marks with those on the master roll. 鈥淭he
results were absolutely astonishing,鈥� says Stahnke. 鈥淭hese people were no
诲耻尘尘颈别蝉.鈥�

Rachmaninoff became Ampico鈥檚 star performer. A company arranger would go to
the pianist鈥檚 Long Island home and work with him, correcting a roll by hand
until he was happy with it, says Stahnke. It was perhaps not surprising that the
company took such pains: in the late 1920s, Rachmaninoff was being paid
$1000 a roll.FIG-mg21656501.JPG

The heyday of the piano roll came to an abrupt end. By the late 1920s, the
radio was already replacing the piano in the parlour, and gramophone recording
had improved dramatically with the switch from acoustic to electric recording.
The Wall Street crash of 1929 signalled the end. Sales of player pianos in the
US slumped from a peak of nearly 350 000 in 1923 to 50 000 by 1931. Ampico was
taken over and its recording pianos destroyed. That didn鈥檛 stop the new owners
issuing rolls and claiming that they were made by a real pianist, when in fact
they were made by expert operators wielding punch machines.

Only one of the few dozen recording pianos from this era is known to have
survived. The QRS recording piano, dating from 1912, owes its existence to the
company鈥檚 arranger, who saved it from the scrapheap. QRS, which still makes
piano rolls in Buffalo, New York, reacquired the piano and even used it to
record new rolls in the late 1960s. In 1992, the American Society of Mechanical
Engineers gave the piano a heritage award in recognition of its contribution to
binary recording.

Though the player piano industry was dead, it refused to lie down. In 1978 it
stuttered back into life when the electronics company Marantz put its
Pianocorder system on the market. Like the reproducing pianos, it divided the
keyboard into two halves. But with a five-bit system for dynamics, it could
reproduce 32 different levels of volume. Like modern player pianos, it used
solenoids to work the keys, but stored its digital music data on cassette tape
rather than floppy discs. Marantz issued a few fresh recordings, including ones
by the jazz virtuoso Oscar Peterson and, the matron鈥檚 heart-throb Liberace.

But the Pianocorder enjoyed only a short life. Advances in computer
technology and the advent of Midi quickly overtook it, and Marantz quietly
killed it off in the mid-1980s. Within a few years, the latest generation of
machines started to arrive. The Viennese piano maker Bosendorfer began marketing
Stahnke鈥檚 piano and Yamaha launched the Disklavier.

These instruments have distinct advantages over their predecessors. Both can
record music as well as play it back. The solenoids in the Disklavier can
produce 127 different levels of hammer velocity, although the lowest 25 or so
are silent because the hammer does not even reach the string. Each note can be
given a different velocity鈥攚hich makes it possible to accent just one
melody note in a chord. The Bosendorfer SE has even greater resolution than the
Disklavier, with 1018 levels of hammer velocity.

In recent years, the competition has hotted up. QRS and Music Systems
Research of Sacramento, California, sell kits that can be fitted to almost any
make of piano. MSR, which has sold 30 000 of its PianoDisc systems over the past
ten years, claims to be the world鈥檚 biggest supplier of computer-controlled
player pianos.

A little light music

Many of the world鈥檚 leading pianists have made the trip to Yamaha鈥檚 studios
in California and Japan to record for the Disklavier. Yamaha has bought the
rights to many of the patents that Stahnke held鈥攏otably the one for
recording the hammer velocity. Stahnke is now a key member of Yamaha鈥檚
Disklavier design team, which is based at Hamamatsu, Japan. His system for
recording piano dynamics recalls the one used by Ampico half a century
ago鈥攁lthough that was not mass-produced.

Each hammer shank on the Disklavier carries a tiny fin, with a small slot cut
in it. Light from an LED at the bass end of the piano is picked up by a
photocell at the treble end. When the hammer starts towards the string, the
leading edge of the fin breaks the beam. The slit in the fin restores the beam
before the second leading edge cuts it again. 鈥淭he velocity is recorded from
leading edge to leading edge,鈥� says Stahnke. The output of LEDs can vary
enormously with temperature, he says, but this very simple technique provides an
elegant solution because the LEDs have to stay constant for only a matter of
milliseconds. 鈥淚 was very proud of it when I thought of it,鈥� he says.

One potential weakness of modern machines is that the performance of their
solenoids deteriorate as they warm up, says Stahnke. The result is that the
hammer velocities can wander slightly from those specified by Midi files.
Stahnke solved this problem on the Bosendorfer SE and Yamaha鈥檚 latest model, the
Disklavier Pro, with fast-acting feedback. Electromagnetic sensors monitor and
adjust the velocity of the solenoid strokes as they push the keys so that notes
sound exactly as loud as they are supposed to.

Since its public debut 10 years ago at a burger bar in Limon, Colorado, the
Disklavier has come far. This year it was on stage with the Boston Pops
orchestra, playing converted piano rolls recorded by the late great composer
George Gershwin. And its most recent starring role is in the Oscar-winning film
As Good as it Gets. The title is appropriate. 鈥淚 think the technology
is now pretty much mature,鈥� says Stahnke. 鈥淭he reproduction is so close to the
original that the human ear cannot tell the difference.鈥�