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EUROPEAN STANDARD EN 62156
NORME EUROPÉENNE
EUROPÄISCHE NORM December 2001
ICS 33.160.40
English version
Digital video recording with video compression 12,65 mm
type D-9 component format 525/60 and 625/50 (digital S)
(IEC 62156:2001)
Enregistrement vidéo numérique Digitale Videoaufzeichnung
avec compression vidéo mit Videokompression 12,65 mm
sur bandes de 12,65 mm format D-9-Komponentenformat
à composante 525/60 et 625/50 525-60 und 625-50 (Digital-S)
(numérique S) type D-9 (IEC 62156:2001)
(CEI 62156:2001)
This European Standard was approved by CENELEC on 2001-12-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,
Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62156:2001 E
Foreword
The text of document 100/394/FDIS, future edition 1 of IEC 62156, prepared by IEC TC 100, Audio,
video and multimedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and
was approved by CENELEC as EN 62156 on 2001-12-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2002-09-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2004-12-01
Annexes designated "normative" are part of the body of the standard.
In this standard, annex ZA is normative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62156:2001 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 60735 NOTE Harmonized as EN 60735:1991 (not modified).
__________
- 3 - EN 62156:2001
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
1)
ITU-R BT.470-6 - Conventional television systems - -
1)
ITU-R BT.601-5 - Studio encoding parameters of digital--
television for standard 4:3 and wide-
screen 16:9 aspect radios
SMPTE 12M 1999 Television, audio and film - Time and--
control code
1) Undated reference.
NORME CEI
INTERNATIONALE IEC
INTERNATIONAL
Première édition
STANDARD
First edition
2001-10
Enregistrement vidéo numérique avec
compression vidéo sur bandes de 12,65 mm
format à composante 525/60 et 625/50
(numérique S) type D-9
Digital video recording with video compression
12,65 mm type D-9 component format 525/60 and
625/50 (digital S)
 IEC 2001 Droits de reproduction réservés  Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun procédé, any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission in
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
XF
PRICE CODE
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue

62156  IEC:2001 – 3 –
CONTENTS
FOREWORD.7
1 Scope.15
2 Normative references .15
3 Abbreviations .17
4 Environment and test conditions .19
4.1 Environment .19
4.2 Reference tape.19
4.3 Calibration tape.19
5 Video tape cassette.19
5.1 General specifications .19
5.2 Datum plane.19
5.3 Window and labels .21
5.4 Colour .21
5.5 Accidental erasure prevention hole.21
5.6 Video tape.21
5.7 Leader/trailer tape.23
5.8 Reels.25
5.9 Lid.25
6 Helical recording – physical characteristics .27
6.1 Tape speed .27
6.2 Sectors.27
6.3 Record location and dimensions.27
6.4 Helical track record tolerance zones.27
6.5 Relative positions of recorded information .29
6.6 Gap azimuth.29
6.7 Transport and scanner .29
7 Helical recording – electrical characteristics .31
7.1 Track contents.31
7.2 Signal processing.31
7.3 Magnetization.33
8 Programme track data .35
8.1 ITI sector.35
8.2 Audio sector .35
8.3 Video sector .41
8.4 Subcode sector .43
8.5 Edit gap.47
9 Longitudinal tracks .47
9.1 Control track .47
9.2 Cue track .49
10 Audio processing.49
10.1 Introduction .49
10.2 Encoding mode .51
10.3 Audio channel allocation.51
10.4 Frame structure.51

62156  IEC:2001 – 5 –
10.5 Audio shuffling .53
10.6 Audio auxiliary data (AAUX) .55
10.7 Error correction code addition .59
11 Video processing.61
11.1 Introduction .61
11.2 Video structure.63
11.3 DCT processing.69
11.4 Quantization.73
11.5 Variable length coding (VLC).75
11.6 The arrangement of a compressed macro block .77
11.7 Arrangement of a video segment .77
11.8 Relationship between compressed macro block and data-sync block.81
11.9 Re-ordering of compressed macro blocks.81
11.10 Video auxiliary data (VAUX) .83
11.11 Error correction code addition .91
12 Subcode processing .93
12.1 Introduction .93
12.2 Subcode data .93
12.3 Error correction code addition .95
13 Interface.97
13.1 Introduction .97
13.2 Data structure .97
13.3 Transmission order.111
13.4 Frame period.113
13.5 Playback speed .113
Figure 1 – Cassette overall shape and dimensions . 155
Figure 2 – Cassette top and side view dimensions (1). 157
Figure 3 – Cassette top and side view dimensions (2). 159
Figure 4 – Cassette bottom and side view dimensions (1). 161
Figure 5 – Cassette bottom and side view dimensions (2). 163
Figure 6 – Cassette bottom and side view dimensions (3). 165
Figure 7 – Cassette datum plane Z and supporting areas. 167
Figure 8 – Detector holes. 169
Figure 9 – Cassette internal construction . 171
Figure 10 – Reel dimensions. 173
Figure 11 – Reel and reel disk relationship . 175
Figure 12 – Tape winding and tape pull out angle . 177
Figure 13 – Reel brake release . 179
Figure 14 – Front cover lock and open/close view. 181
Figure 15 – Rear cover open/close view . 183
Figure 16 – Area for tape loading mechanism . 185
Figure 17 – Cassette top and bottom half securing screw positions. 187
Figure 18 – Location and dimensions of recorded tracks. 189

62156  IEC:2001 – 7 –
Figure 19 – Sector location from programme area reference point . 189
Figure 20 – Location and dimensions of tolerance zone of helical track record. 191
Figure 21a – Possible scanner configuration (525/60 and 625/50 system)-Overhead view . 193
Figure 21b – Possible scanner configuration (525/60 and 625/50 system)-Side view . 193
Figure 21c – Possible scanner configuration (525/60 and 625/50 system)-Side view
with control track head.195
Figure 22 – Sector arrangement on single helical track (525/60 and 625/50 systems) . 197
Figure 23 – Bit stream before interleaved NRZI modulation . 199
Figure 24 – Pre-coding . 199
Figure 25 – Structure of ITI sector . 199
Figure 26 – Structure of audio sector after 24-25 modulation . 199
Figure 27 – Structure of sync blocks in audio sector . 201
Figure 28 – Structure of video sector after 24-25 modulation . 201
Figure 29 – Structure of sync blocks in video sector . 203
Figure 30 – Structure of subcode sector after 24-25 modulation. 203
Figure 31 – Structure of sync blocks in subcode sector. 205
Figure 32 – Structure of ID data. 207
Figure 33 – Flux polarity of control track . 207
Figure 34 – Flux levels.209
Figure 35 – Sample to data byte conversion for 16 bits . 209
Figure 36 – Audio shuffling pattern for 525/60 system. 211
Figure 37 – Audio shuffling pattern for 625/50 system. 213
Figure 38 – Arrangement of AAUX packs in audio sector . 215
Figure 39 – Transmitting samples for 525/60 systems. 217
Figure 40 – Transmitting samples for 625/50 system . 219
Figure 41 – DCT block and the pixel coordinates . 219
Figure 42 – DCT block arrangement . 221
Figure 43 – Macro block and DCT blocks. 221
Figure 44 – Super blocks and macro blocks in a video frame for 525/60 system . 223
Figure 45 – Super blocks and macro blocks in a video frame for 625/50 system . 225
Figure 46 – Macro block order in a Super block . 227
Figure 47 – The output order of a weighted DCT block. 227
Figure 48 – Measurement method of DCT operation precision . 227
Figure 49 – Area number . 229
Figure 50 – Arrangement of compressed macro block. 229
Figure 51 – Arrangement of video segment after bit rate reduction . 231
Figure 52 – Video error code . 231
Figure 53 – Relation between the macro block number and the data sync block for
sector 0 . 233
Figure 54 – Relation between the macro block number and the data sync block for
sector 1 . 235

62156  IEC:2001 – 9 –
Figure 55 – Arrangement of VAUX packs in VAUX sync blocks . 237
Figure 56 – Arrangement of VAUX EXTRA LINE packs in VAUX sync block. 237
Figure 57 –Data allocation of VAUX EXTRA LINE pack for 525/60 system. 239
Figure 58 – Data allocation of VAUX EXTRA LINE pack for 625/50 system. 241
Figure 59 – Arrangement of subcode data packs in subcode sector . 243
Figure 60 – Bit assignment for the subcode data and subcode parity . 243
Figure 61 – Block diagram of digital interface. 245
Figure 62 – Data structure for transmission. 245
Figure 63 – Transmission order of DIF blocks in a DIF sequence. 247
Figure 64 – ID data in a DIF block. 249
Figure 65 – Data in the header section . 249
Figure 66 – Data in the subcode section . 251
Figure 67 – Data in the VAUX section . 251
Figure 68 – Data in the audio section. 251
Figure 69 – Data in the video section. 253
Table 1 – Record location and dimensions. 113
Table 2 – Sector location from programme area reference point (525/60 system) . 115
Table 3 – Sector location from programme area reference point (625/50 system) . 115
Table 4 – Possible scanner design parameters (525/60 and 625/50 systems) . 117
Table 5 – Bit stream of SSA. 117
Table 6 – Bit stream of TIA . 119
Table 6a . 119
Table 6b . 119
Table 7 – ID0 in audio sector . 119
Table 8 – Audio application ID . 119
Table 9 – Track pair number . 119
Table 10 – Sequence number (525/60 and 625/50 systems) . 121
Table 11 – Bit assignment of ID code words . 121
Table 12 – ID data in video sector. 121
Table 13 – Video application ID . 121
Table 14 – Subcode application ID. 123
Table 15 – Application ID for track . 123
Table 16 – Construction of audio block . 123
Table 17 – The number of samples per frame (sequence locked mode) . 123
Table 18 – The number of samples per frame (average locked mode). 125

62156  IEC:2001 – 11 –
Table 19 – The allowance range of the accumulated difference of values between the
numbers of audio samples per frame in CH1, CH2, CH3 and CH4 . 125
Table 20 – AAUX data of the main area . 125
Table 21 – Mapping of AAUX source pack . 125
Table 22 – AAUX source control pack . 127
Table 23 – Mapping of AAUX NO INFO pack . 127
Table 24 – The construction of video signal sampling . 127
Table 25 – Class number and the DCT block . 129
Table 26 – An example of the classification for reference. 129
Table 27 – Quantization step . 129
Table 28 – Length of code word. 131
Table 29 – Code words of variable length coding . 133
Table 30 – Definition of STA . 135
Table 31 – Code words of QNO . 135
Table 32 – VAUX data of the reserved area . 137
Table 33 – Mapping of VAUX source pack . 137
Table 34 – Mapping of VAUX source control pack. 137
Table 35 – Mapping of VAUX format pack. 137
Table 36 – Mapping of VAUX EXTRA LINE pack. 137
Table 37 – Mapping of NO INFO pack. 139
Table 38 – Mapping of subcode data . 139
Table 39 – Mapping of MTC. 141
Table 40 – Mapping of STC . 141
Table 41 – Mapping of subcode NO INFO pack. 141
Table 42 – Mapping of MUB. 141
Table 43 – Mapping of SUB . 141
Table 44 – DIF block type . 143
Table 45 – DIF sequence number (525/60 system) . 143
Table 46 – DIF sequence number (625/50 system) . 143
Table 47 – Application ID for track . 145
Table 48 – DIF blocks and subcode sync blocks . 145
Table 49 – DIF blocks and VAUX data sync blocks . 147
Table 50 – Mapping of VAUX source pack for interface. 147
Table 51 – Mapping of VAUX source control pack for interface . 147
Table 52 – DIF blocks and audio data sync blocks . 149
Table 53 – Mapping of AAUX source pack for interface. 151
Table 54 – Mapping of AAUX source control pack for interface . 151
Table 55 – DIF blocks and compressed macro blocks . 153

62156  IEC:2001 – 13 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIGITAL VIDEO RECORDING WITH VIDEO COMPRESSION
12,65 mm TYPE D-9 COMPONENT FORMAT
525/60 AND 625/50 (DIGITAL S)
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62156 has been prepared by IEC technical committee 100: Audio,
video and multimedia systems and equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
100/394/FDIS 100/425/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
The committee has decided that the contents of this publication will remain unchanged until
2005. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
62156  IEC:2001 – 15 –
DIGITAL VIDEO RECORDING WITH VIDEO COMPRESSION
12,65 mm TYPE D-9 COMPONENT FORMAT
525/60 AND 625/50 (DIGITAL S)
1 Scope
Intraframe bit rate reduction is applied to video data prior to recording.
This International Standard specifies the content, format and recording method of the data
blocks containing video, audio, and associated data that form the helical records on 12,65 mm
tape in cassettes.
In addition, this standard specifies the content, format and recording method of the
longitudinal record containing tracking information for the rotating head associated with the
helical records, and also cue audio, and control tracks.
One video channel and four independent audio channels are recorded in the digital format.
Each of these channels is capable of independent editing.
The video channel records and reproduces a component television signal in the 525 line
system with a frame frequency of 29,97 Hz (hereinafter referred to as the “525/60 system”)
and in the 625 line system with a frame frequency of 25,00 Hz (hereinafter referred to as the
“625/50 system”).
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. For dated references, subsequent
amendments to, or revisions of, any of these publications do not apply. However, parties to
agreements based on this International Standard are encouraged to investigate the possibility
of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of IEC
and ISO maintain registers of currently valid International Standards.
ITU-R BT.470-6, Conventional television systems
ITU-R BT.601-5, Studio encoding parameters of digital television for standard 4:3 and wide-
screen 16:9 aspect ratios
SMPTE 12M-1999, Television, Audio and Film – Time and Control Code

62156  IEC:2001 – 17 –
3 Abbreviations
AAUX: Audio auxiliary data
AP1: Audio application ID
AP2: Video application ID
AP3: Subcode application ID
APT: Track application ID
Arb: Arbitrary
AS: AAUX source pack
ASC: AAUX source control pack
B/W: Black and white flag
CGMS: Copy generation management system
DBN: DIF block number
DCT: Discrete cosine transform
DIF: Digital interface
DSF: DIF sequence flag
ECC: Error correction code
EFC: Emphasis channel flag
EOB: End of block
FSC: DIF block set number
IDP: ID parity
ITI: Initial track information
LF: Locked mode flag
MUB: Main users binary group pack
OM: Overwrite margin
QNO: Quantization number
QU: Quantization
Res: Reserved for future use. Default value shall be set to “1”
SMP: Sampling frequency
SSA: Start sync area
SSYB: Subcode sync block number
STA: Status of the compressed macro block
STC: Sub time code pack
SUB: Sub users binary group pack
Syb: Sync block number
TF: Transmitting flag
TIA: Track information area
Trp: Track pair number
VAUX: Video auxiliary data
VLC: Variable length coding
VS: VAUX source pack
VSC: VAUX source control pack
VSM: Vibrating sample magnetometre

62156  IEC:2001 – 19 –
4 Environment and test conditions
4.1 Environment
Tests and measurements made on the system to check the requirements of this standard
shall be carried out under the following conditions.
Temperature:
(20 ± 1) °C
Relative humidity:
(50 ± 2) %
Barometric pressure: from 86 kPa to 106 kPa
Tape conditioning: not less than 24 h
Tape tension: from 0,3 N to 0,45 N
(Measured at the entrance of the drum)
4.2 Reference tape
Blank tape for reference recordings shall be available from any source producing tape
meeting the tape characteristics as defined by this standard.
4.3 Calibration tape
The calibration tapes meeting the requirements of 4.3.1 and clause 5 should be available from
manufacturers who produce digital tape recorders and players in accordance with this
standard.
4.3.1 Record locations and dimensions
Tolerances shown in table 1 will be reduced by 50 %.
4.3.2 Calibration signals
Video, audio and cue channels shall be recorded on the calibration tape:
Video: 100/0/100/0 colour bars
Audio and cue: 1 kHz tone at 20 dB below full scale
5 Video tape cassette
5.1 General specifications
5.1.1 The dimensions of the cassette used for recording shall be in accordance with figures
1 to 17.
5.1.2 The magnetic coating on the tape shall face out of the cassette as specified in
figure 12.
5.2 Datum plane
5.2.1 Datum plane Z is determined by datum areas A, B and C as specified in figure 7.

62156  IEC:2001 – 21 –
5.2.2 Datum plane Y shall be orthogonal to datum plane Z and shall run through the centre
of datum hole (A) and datum hole (B) as specified in figures 4 and 5.
5.2.3 Datum plane X shall be orthogonal to both datum plane Y and datum plane Z and shall
run through the centre of datum hole (A) as specified in figures 4 and 5.
5.3 Window and labels
Window and label areas shall be as specified in figures 2 and 3.
5.4 Colour
Window and reel upper flange: transparent
Cassette shell: A colour shall be selected so that overall light transmission of the cassette
shell including wound tape is less than 2 % when the light onto the cassette
upper surface is measured at the positions of the VTR light sensors. The VHS
cassette optical tester VT-2M manufactured by JVC or equivalent measuring
instrument shall be used.
5.5 Accidental erasure prevention hole
The dimensions and locations of the accidental erasure prevention hole are shown in figure 8.
The function shall be defined as follows:
Open: total record lock out (audio, video, cue, time code, and control track)
Closed: possible to record
5.6 Video tape
5.6.1 Base
The base material shall be polyester or equivalent.
5.6.2 Width
The tape width shall be 12,650 mm ± 0,010 mm.
5.6.3 Width fluctuation
Width fluctuation of the video tape shall be less than 6 μm.
5.6.4 Reference edge straightness
Maximum deviation of the reference edge straightness shall be 6 μm peak-to-peak. Edge
straightness fluctuation is measured at the edge of a moving tape positioned by three guides,
having contact on the same edge of the tape. Distance between guides is 85 mm from the first
to the second guide, and 85 mm from the second to the third guide. Edge measurements are
averaged over a 10 m length of tape. Measurements are made at a point 5 mm in the direction
towards the first guide from the midpoint between the first and second guide.
5.6.5 Tape thickness
The tape thickness shall be 14,4 μm ± 0,5 μm or 12,4 μm ± 0,4 μm.

62156  IEC:2001 – 23 –
5.6.6 Transmissivity
Transmissivity shall be less than 1,2 %, measured over the range of wavelength 800 nm to
1 000 nm.
5.6.7 Strength
Both of the following conditions A and B shall be fulfilled.
(A) Dynamic collapse strength (Sd) is greater than 0,6 N.
3 2
(B) Young's modulus (E) is greater than 10,3 × 10 N/mm
E = El + Et
El: Longitudinal direction Young's modulus(N/mm )
Et: Transverse direction Young's modulus(N/mm )
Sd is the force in the tape transverse direction that can cause tape edge buckling when the
tape is pressed against the flange of the VTR guide roller. Sd shall be measured with the JVC
VG-5 measuring instrument that simulates such tape edge buckling and measures the force in
the transverse direction.
5.6.8 Yield strength
The yield strength shall be 18 N or more by the following test method:
Fix one end of a sample tape of length 200 mm and pull the other end at a speed of
100 mm/min. The yield strength is the force at which 5 % elongation is observed.
5.6.9 Magnetic coating
The magnetic layer of the tape shall consist of a coating of metal particles or equivalent, and
the coercivity shall be a class of 1 800 (approximately 1 800 Oe / 143 000 A/m) with an
applied field of 800 000 A/m (10 000 Oe) as measured by a vibrating sample magnetometer
(VSM).
5.6.10 Length
Tape length and record time shall be as follows:
Record time Length
min m
+3
+3
104 370
+3
+3
5.7 Leader/trailer tape
5.7.1 The light path shall be as specified in figure 9.
5.7.2 The cassette shall include leader and trailer tape. When attached to the hub, the
length between the splice point and the clamping point on the reel hub shall be
170 mm ± 20 mm.
62156  IEC:2001 – 25 –
5.7.3 The leader/trailer tape material shall be polyester or equivalent having transmissivity of
at least 50 %. The light transmission shall be measured with a measuring instrument based
on the following combination of devices:
Light source: 2 000 K halogen lamp
Light sensor: Photo diode having maximum sensitivity at 940 nm
The JVC VT-1M tape optical tester that conforms to the above condition shall be used to
measure light transmission of leader/trailer tape.
5.7.4 The width of the leader/trailer tape shall be 12,65 mm ± 0,03 mm.
+5
5.7.5 The thickness of the leader/trailer tape shall be 40 μm. The splicing tape used to
−25
attach the leader/trailer tape shall be applied to the back of the tape.
5.7.6 Length of splicing tape shall be 12 mm to 19 mm.
5.7.7 Splicing gap shall be 0 μm to 70 μm.
5.7.8 When attached to the hub, the leader/trailer tape shall not separate when subjected to
a force of 30 N or less.
5.8 Reels
5.8.1 The dimensions of the reels and the relationship between the reels and the reel disks
shall be as specified in figures 10 and 11.
5.8.2 The reels shall be locked automatically when the cassette is removed from the
recorder/player.
5.8.3 When a cassette is inserted into the recorder/player, the reels shall be unlocked
automatically as specified in figure 13. The force needed to release the reel lock shall be
0,7 N or less when the reel brake release pin is inserted 9,5 mm from the datum plane Z.
+0,4
5.8.4 The reels shall be held in position by a reel spring with a force of 1,75 N as
−
0,2
specified in figure 11.
5.9 Lid
5.9.1 The lid shall be unlocked and opened by the recorder/player when the cassette is
inserted. The force needed to unlock the lid shall be less than 0,15 N as specified in figure 14.
5.9.2 The front cover opening force shall be less than 1 N at the 27 mm opening distance as
specified in figure 14.
5.9.3 The front cover shall be lifted by the recorder/player to the position shown in figure 14.
5.9.4 The rear cover shall be lifted by the recorder/player to the position shown in figure 15.

62156  IEC:2001 – 27 –
5.9.5 The minimum space within the cassette for the VTR loading mechanism shall be as
shown in figure 16. The shaded area of figure 16 is intended to indicate the areas available
for loading (threading) the tape. Note that the dimensions defining this space are not cassette
dimensions.
6 Helical recording – physical characteristics
6.1 Tape speed
The tape speed shall be 57,737 mm/s for the 525/60 system and 57,795 mm/s for the 625/50
system.
The tolerance is ±0,5 %.
6.2 Sectors
Each recorded track contains ITI sectors, audio sectors, video sectors and a subcode sector.
6.3 Record location and dimensions
6.3.1 Record location and dimensions
Record location and dimensions for continuous recording shall be as specified in figure 18
and table 1. In recording, sector locations on each helical track shall be contained within the
tolerance specified in figure 20 and in tables 2 and 3. Sector locations are derived from
clause 6, figure 22 and the total length of the helical track (L).
The reference edge of the tape and dimensions specified
...