Sony MINIDISC User Manual

MINIDISC MANUAL

V3.0E

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1. The MiniDisc System

1.1. The Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2. What it is and How it Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.3. Serial Copy Management System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.4. Additional Features of the Premastered MD . . . . . . . . . . . . . . . . . . . . . 8

2. The production process of the premastered MD

2.1. MD Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.2. MD Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3. Input components specification

3.1. Sound Carrier Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3.2. Additional TOC Data / Character Information . . . . . . . . . . . . . . . . . . 17

3.3. Label-, Artwork- and Print Films . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.4. MiniDisc Logo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4. Sony DADC Austria AG

4.1. The Company . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

5. Appendix

Form Sheets

Introduction

The quick random access of Compact Disc players has become a necessity for

music lovers. The high quality of digital sound is now the norm. The future

of personal audio must meet the above criteria and more.

That’s why Sony has created the MiniDisc, a revolutionary evolution in the

field of digital audio based on an advanced miniature optical disc.

The MD offers consumers the quick random access, durability and high

sound quality of optical media, as well as superb compactness, shock-

resistant portability and recordability. In short, the MD format has been

created to meet the needs of personal music entertainment in the future.

Based on a dazzling array of new technologies, the MiniDisc offers a new

lifestyle in personal audio enjoyment.

The Features

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1. The MiniDisc System

1.1. The Features

With the MiniDisc, Sony has created a revolutionary optical disc. It offers all the features
that music fans have been waiting for.

Quick Random Access

The MiniDisc offers quick random access to the music selection or phrase of your
choice; something only a disc is capable of.

Total Durability

The MiniDisc can never stretch, break or tangle like cassette tapes. Since the free
floating optical pick-up never touches the surface, scratches are impossible.

Superb Compactness

The MiniDisc itself is only approximately 64 mm in diameter, and the cartridge is
72 x 68 x 5 mm.

And because the MiniDisc is smaller, so is the MiniDisc player.

Shock-Resistant Portability

The MiniDisc is resistant against shocks and vibrations. New technology, using an
advanced semiconductor memory, provides almost total shock resistance so there
is no skipping and jitter even while jogging or driving.

Easy to Handle

The disc is protected in a cartridge. It is easy to handle and the ideal sound carrier for
mobile use.

Unsurpassed Digital Sound

The MiniDisc is based on the same noiseless and distortion-free digital recording
technology as the compact disc. So whether you are recording your own or listening
to prerecorded music, you have the optimum in audio quality wherever you go.

Recordable Disc

4 Track Recording: “A disc which records” is every music fan’s dream come true.
The MiniDisc offers about 74 minutes digital recording on one tiny disc.

What it is and How it works

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1.2. What it is and How it Works

Two Kinds of MiniDiscs are Available:

Premastered MiniDiscs for
Music Software

Premastered MiniDiscs are used most commonly
for music and are sold in record stores just the
same as compact cassettes and CDs are.
MiniDiscs, just like CDs, are manufactured in
large volumes by high-speed injection molders,
and the music signals are recorded during repli­cation in the form of pits.
Forget the times when you would worry about
cassette tapes becoming worn out or wrinkled.
Moreover, the discs are encased in a cartridge, so
there is no worry about their being scratched.
The design of the premastered MiniDisc cartridges

Optical Pick-up of MD Player:

is special. Prerecorded music packages require a
label, featuring the artist’s picture or other infor­mation – for it is the artwork that most often
captures the buyer’s eye. Therefore the top face
of the cartridge is left completely free for the
label. A window for the laser beam to read the
disc is only necessary on the bottom face.

Recordable MiniDiscs

Magneto-optical (MO) technology forms the heart
of the recordable MiniDisc technology. Not only
are MO discs durable enough to withstand being
rerecorded about 1 million times, they also have a
life expectancy approaching that of CDs.
When recording the MO discs, a laser beam must
be focused onto the magnetic layer from behind
while a magnetic field is applied to the front. For
this reason, the cartridges for recordable MiniDiscs
have a read/write window on both sides.

The optical pick-up developed for the MD system
has the remarkable ability to read both recorda­ble and premastered MiniDiscs. For recordable
discs, the pick-up detects the magnetic structure
along the track. For premastered optical discs, it
detects the geometric structure along the track.
The MD system is based on the design of the
standard CD pick-up with the addition of a MO
signal readout analyzer and two photodiodes.
During playback of recordable discs a 0.5mW laser

is focused onto the magnetic layer. The magnetic
signal on the disc affects the polarization of the
reflected beam. The direction of polarization is
converted into light intensity by the MO signal
readout analyzer. Depending on the direction of
polarization one of the two photodiodes will
detect more light. The electrical signals from the
photodiodes are subtracted and depending on
whether the difference is positive or negative, a
“1” or “0” signal is read.

MiniDisc Pick-up Technology

0 1

Cross sectional view

of recording track

Laser Laser

Recordable disc Premastered disc

0 1

High intensity Low intensity

MD

Laser Beam

R

e

c

o

Objective Lens

k

c

tra

r

d

i

g

n

Photo Detector B

Polarized
beam splitter

Photo Detector A

MO signal

+

-

+
+

Pit signal

What it is and How it Works

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The same 0.5mW laser is used for the playback of
premastered optical discs. The amount of light
reflected depends on whether or not a pit exists
on the surface of the disc. If there is no pit, a
high proportion of the light is reflected back
through the beam splitter and analyzer into the
photodiodes. If a pit does exist, some of the light
is diffracted and less light reaches the photodi­odes. The electrical signals from the photodiodes
are added up in this case and depending on the
sum, a “1” or “0” is read.

Overwrite Technology

In order to meet the requirements of a compact,
lightweight, recordable audio system for perso­nal use, the MD system employs a newly develo­ped Sony magneto-optical (MO) disc that utilizes
magnetic field modulation with direct “overwri­te” capability. With MO disc technology, the
recording of data requires the use of a laser and
a polarizing magnetic field. When the magnetic

layer in the disc is heated by the laser to a tem­perature above the Curie point (approximately
200° C), it temporarily looses its coercive force.
As the disc rotates and the irradiated domain
returns to normal temperature, its magnetic ori­entation is determined by an externally applied
magnetic field. Polarities of “N” and “S” can
thus be recorded, corresponding to digital data
“1” and “0”.

Unlike conventional MO rewrite mechanisms, the
”Sony MD overwrite system” positions a magne­tic head directly accross from the laser source on
the opposite side of the disc. A magnetic field
corresponding to the input signal is generated
over the laser spot. The rotation of the disc then
displaces the area to be recorded, allowing the
temperature at the spot to drop back below the
Curie point. At that point, the domain takes on
the polarity of the applied magnetic field regard­less of the polarity that previously existed.

Overwrite Mechanism

1
0

Move direction of Disc

New Old

Frozen magnetic pattern
after cooling below
Curie Point

Head Drive signal

Laser Beam

S SN NSS NN

Heated area by Laser
above Curie Point
(erased magnetic pattern)

Recording Head

Magnetic field of
Recording Head

Cross section of
MO-Layer with
magnetic pattern

Top view
of one Track

What it is and How it Works

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The ease of quick random access was made possi­ble by the development of the Compact Disc (CD).
The CD instantaneously provides random access to
the beginning of any desired music selection. After
using a CD player, the time to reach the music sel­ection of your choice with cassette tape players
seems extremely cumbersome.
The MiniDisc provides the same high-speed random
access for recordable discs as well as for premaste­red discs. In addition, the recordable MiniDisc has a
circumferential microgroove or ”pre-groove”, which
is formed when the polycarbonate substrate is injec­tion molded. This pre-groove is the basis for the
tracking servo and spindle servo operation during
recording or playback.
Address information is recorded at intervals of 13.3
milliseconds using a technology that places infinite­simal zigzags on this pre-groove. Therefore, the
disc has all the addresses already notched along the
groove even with no recording. The result is a

stable and quick random access, as well as a variety
of optional features, including programming of
the playback sequence e.g.: rearranging the
sequence of the titles recorded on the MD without
rerecording of the music information in a matter of
seconds.
This is possible because of the “User TOC Area”,
located around the inner edge of the microgroove,
which only contains the order of the music. This
system is similar to the “directory management
system” of floppy discs. In other words, starting
and ending addresses for all music tracks recorded
on the disc are stored in this area, enabling easy
programming just by rewriting the addresses. This
supports also other features: it is possible to erase
a track out of a sequence and during playback no
gap in the remaining music will be heard. The era­sed segment is allocated to the free space – it is
possible to record a piece of music independent of
the number of segments used.

Quick Random Access

Reprogramming the
Order of Music

1. Ordinary Method:

A: Before Rearranging

Disc Signal

B: After Rearranging

2. MiniDisc:

A: Before Rearranging

Disc Signal

B: After Rearranging (No Change of Music Data)
Connecting two Tracks:

Additional Reprogramming the Order:

Lead in 1 2 3 4 Lead out

Lead in

Lead in

Lead in

Music Data and Order are Recorded Time-Wise

A B C D E F G HInner Edge Outer Edge

1 2 3

Music Data and Order are Recorded Area-Wise

UTOC

Rearranged Area

UTOC

Only Music Data is Recorded Lead out

UTOC Data

UTOC Data

TNO START STOP

Only Music Data is Recorded

TNO START STOP

TNO START STOP

Rearranged Area

1
2
3
4

1
2
3

1
2
3

Lead out

A

B

C

D

E

F

G

H

Lead out

A

D

E

F

G

H

A

D

G

H

E

F

Threshold of Hearing:

As sound level diminishes, there is a level below
which the human ear cannot detect. This thres­hold varies with frequency. The threshold of
audibility is lowest for sounds with a frequency
of approximately 4kHz; that is, sounds close to
this frequency are most easily detected by the
ear. By analyzing the frequency components of
an audio signal, it is possible to identify those
components that lie below the threshold of hea­ring. Such components can be removed from
the original signal without affecting perceived
sound quality.

Masking Effect:

If two sounds, one loud and the other soft, are
produced simultaneously and they are close to
one another in frequency, the softer sound be­comes difficult or even impossible to hear.
Therefore, when an audio signal has a high level
component and a low level component at neigh­bouring frequencies, the latter can be removed
without affecting perceived sound quality.
Moreover, with increasing overall signal amplitu­de, it becomes possible to remove a greater num­ber of components without audible effect.

What it is and How it Works

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ATRAC Digital Audio Compression
Technology

In order to provide approximately 74 minutes of
music on the 2.5-inch MiniDisc, a digital audio
compression technology called “ATRAC” (Adaptive
Transform Acoustic Coding) has been newly deve­loped. This technology compresses information
down to approximately one fifth of the amount of
data usually required.
In 16-bit linear encoding, currently used in the CD
and DAT formats, with a sampling frequency of

44.1 kHz, the analog signal is sampled approxim
ately once every 0.02 milliseconds. Each sample is
quantized at 16-bit resolution into one of 65536
possible values. Therefore, with CD and DAT, when
the analog signal is converted to digital data in real
time, 16 bits of data are used every 0.02 millise­conds, regardless of the amplitude of the signal and
whether or not a signal is present at all.

ATRAC starts with the same 16-bit digital data but
analyzes segments of the data for waveform content
every 11.6 msec. Based on this analysis, ATRAC
extracts and encodes only those frequency compo­nents that are actually audible to the human ear.

This method of encoding is far more efficient than
the linear coding technique used for CD and DAT,
yet sound quality remains comparable. The following
underlying psychoacoustic principles are used during
this conversion.

Psychoacoustic principles:

Masking Effect

F6 FnF4F1

50 400 4k 20k

Threshold of
Hearing

Level

Sampling Distribution and Acoustic Effect

Level

F6 FnF4F1

50 400 4k 20k

Freq. (Hz)

Sampling from ATRAC and its Level

Waveform analysis:

Level

512 Samples

0.02 msec

Level

11.6 msec

analyze the waveform
during approx

11.6 msec into
frequency components

Time

Frequency F1

Level

Level

Frequency F4

Frequency Fn

Shock-Resistant Memory

Conventional optical pick-up systems can easily
mistrack when subjected to shock or vibration. In
digital audio CDs, this causes “skipping” or
muting. Resistance to shock and vibration is a vir­tual prerequisite for true portable personal audio
applications. In the MD system, Sony has solved
this problem with a unique shock-resistant
memory.
While the MD pick-up can read information off
the disc at a rate of 1.4Mbit per second, the
ATRAC decoder requires a data rate of only

0.3Mbit per second for real time playback. This
difference in processing speed enables the use of
a readahead buffer, placed between the pick-up
and the decoder. If a 4Mbit memory chip is used
for the buffer, it can store up to 10 seconds of
digital information. Should the pick-up be jarred
out of position, the correct information continues
to be supplied to the ATRAC decoder from the

buffer memory. As long as the pick-up returns to
the correct position within 10 seconds, the
listener never experiences mistracking or muting.
Since signals enter the buffer memory faster than
they leave it, the buffer will eventually become
full. At that point, the MD player momentarily
stops reading information from the disc; it resu­mes reading as soon as there is again room in the
memory chip.
Using a concept called sector repositioning, the
MD pick-up has the ability to quickly resume rea­ding from the correct point after being displaced.
When signals are recorded on the MiniDisc (either
recordable MO or premastered optical media),
address information is assigned every 13.3 milli­seconds. When a pick-up is shifted out of place,
the MD player quickly recognizes the disruption,
identifies the wrong address, and instantly returns
the pick-up to the correct position.

What it is and How it Works

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Shock-Resistant Memory

Optical Pick-up

Digital Music Data
Analog Music Data
Flow of Music Data

4 Mbit Memory

1.4 Mbit / sec

Decoder

0.3 Mbit / sec

D/A converter

Amplifier