1、BRITISH STANDARD BS EN 60574-21:1994 BS 5817-21: 1994 IEC 574-21: 1992 Specification for Audiovisual, video and television equipment and systems Part 21: Video tape leader and trailer for education and training applications The European Standard EN60574-21:1993 has the status of a British Standard U
2、DC 621.397.13:621.397.4:371.333BSEN60574-21:1994 This British Standard, having been prepared under the directionof the Electronic Equipment Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 15 April1994 BSI 12-1999 The following BSI reference
3、s relate to the work on this standard: Committee reference EEL/32 Draft for comment 89/21779 DC ISBN 0 580 23302 2 Cooperating organizations The European Committee for Electrotechnical Standardization (CENELEC), under whose supervision this European Standard was prepared, comprises the national comm
4、ittees of the following countries: Austria Italy Belgium Luxembourg Denmark Netherlands Finland Norway France Portugal Germany Spain Greece Sweden Iceland Switzerland Ireland United Kingdom Amendments issued since publication Amd. No. Date CommentsBSEN60574-21:1994 BSI 12-1999 i Contents Page Cooper
5、ating organizations Inside front cover National foreword ii Foreword 2 1 Scope 3 2 Content 3 3 Specification of signals 3 4 Trailer Section E, Figure 1 3 Figure 1 Diagram showing the signals recorded on the leader andtrailerandthe relevant timings 4 National annex NA (informative) Committees respons
6、ible Inside back coverBSEN60574-21:1994 ii BSI 12-1999 National foreword This British Standard has been prepared under the direction of the Electronic Equipment Standards Policy Committee and is the English language version of EN60574-21:1993 Audiovisual, video and television equipment and systems P
7、art21: Video tape leader and trailer for education and training applications, published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC574-21:1992, published by the International Electrotechnical Commission (IEC). Agreement has been given for this s
8、tandard to be cross-referenced as Part21 of the BS5817 series for ease of reference in relation to other Parts of the series. BS5817 consists of the following Parts. Part 1: General; Part 2: Definitions; Part 3: Specification for connectors for the interconnection of equipment in audiovisual systems
9、; Part 4: Specification for matching values for the interconnection of equipment in a system; Part 5: Control, synchronization and address codes; Section 5.1: Synchronized tape/visual operating practice; Section 5.2: Method of operation, for pulsed cue tone control systems for two still projectors;
10、Part 6: (Not allocated); Part 7: Guide for safe handling and operation of audiovisual equipment; Part 8: Symbols and identification; Part 9: (Not allocated); Part 10: Specification for audio cassette systems; Part 11: Methods for operating video recording systems to facilitate browsing; Part 12: (No
11、t allocated); Part 13: Specification for a digital counter for audio cassette systems; Part 14: Specification for audio striped card system; Part 15: Specification for audio pages; Part 16: Specification for labelling for educational audio cassettes; Part 17: Methods for specifying and measuring the
12、 performance characteristics of audio-learning systems; Part 18: Specification for connectors for automatic slide projectors with built-in triacs for audiovisual application; Part 19: (Not allocated); Part 20: Methods of measuring and reporting the performance of16mm sound film projectors; Part 21:
13、Video tape leader and trailer for education and training applications.BSEN60574-21:1994 BSI 12-1999 iii A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Stand
14、ard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi toiv, theENtitle page, pages2 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendmen
15、ts incorporated. This will be indicated in the amendment table on the inside front cover.iv blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 60574-21 December 1993 UDC 621.397.13:621.397.4:371.333 Descriptors: Electroacoustic equipment, recording apparatus, video recording, television syste
16、ms, video signals, adjustment, specifications, identification English version Audiovisual, video and television equipment and systems Part 21: Video tape leader and trailer for education and training applications (IEC 574-21:1992) Equipements et systmes audiovisuels, vido et de tlvision Partie 21: A
17、morce et fin de bande vido utilise pour lenseignement et la formation professionnelle (CEI 574-21:1992) Audiovisuelle, Video- und Fernsehgerte und -anlagen Teil 21: Videoband-Vorspann und -Nachspann fr Lehr- und bungszwecke (IEC 574-21:1992) This European Standard was approved by CENELEC on1993-12-0
18、8. 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 obtain
19、ed 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 Centra
20、l Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
21、CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1993 Copyright reserved to CENELEC members Ref.No.EN60574-21:1993EEN60574-21:1993
22、BSI 12-1999 2 Foreword The CENELEC questionnaire procedure, performed for finding out whether or not the International Standard IEC574-21:1992 could be accepted without textual changes, has shown that no common modifications were necessary for the acceptance as European Standard. The reference docum
23、ent was submitted to the CENELEC members for formal vote and was approved by CENELEC as EN60574-21 on8December1993. The following dates were fixed: latest date of publication of an identical national standard (dop) 1995-03-15 latest date of withdrawal of conflicting national standards (dow) 1995-03-
24、15EN60574-21:1993 BSI 12-1999 3 1 Scope 1.1 This part of IEC574 specifies the minimum requirements for recordings on the leaders and trailers of video recordings to assist users to adjust equipment for optimum performance prior to the start of recorded programme material. It also specifies the audio
25、 and video information that precedes and follows the recorded programme material to ensure proper identification of the programme and to allow proper cue-up of and exit from the programme. 1.2 The signals recorded on the leaders and trailers are not intended as test signals for the measurement of th
26、e performance of a system. 2 Content 2.1 A diagram representing the signals and timings on the leader and trailer is given in Figure 1. 2.2 The leader shall contain video and analogue or digital audio alignment signals for at least30s, and preferably for60s, to enable the display equipment to be set
27、 to the optimum levels. The audio alignment signals shall be of the same type (analogue or digital) as the audio programme signals. 2.3 The alignment section should be followed by programme identification for approximately12s, followed by3s of black burst and silence, prior to the start of the progr
28、amme. 3 Specification of signals 3.1 Leader for adjustments Section A, Figure 1 3.1.1 Video signal: Colour bars should be recorded for at least30s. The composition of the bars signal should be the recommended form for the system to be recorded, and the tape format. 3.1.2 Audio (analogue or digital):
29、 A frequency of approximately1000Hz may be used for the tone signal, which may be of the same duration as the bars specified in3.1.1. The level should be at the reference level specified for the tape format which is generally set by the AGC circuit and indicated on the audio level meter of the video
30、 tape recorder. Audio 1 and 2 should carry the same signal in phase, and for stereo the left-hand signal may be identified by signal interruption of approximately0,25s, every3s or by recording the left-hand signal only for at least15s followed by both left and right for15s. NOTEA frequency of approx
31、imately400Hz may be used for analogue audio signals. 3.2 Programme identification Section B, Figure 1 3.2.1 The video signal should contain details of the programme title or sub-title and may also include a count-down clock. The duration of this signal is nominally12s, but shall cut to black at3 0,1
32、s before the programme starts. 3.2.2 The audio channel may contain a statement of the programme title and/or a short audio signal of one-second intervals to provide a count-down. These signals shall finish as the video signal in3.2.1 cuts to black3s before the programme starts. 3.3 Black burst and s
33、ilence Section C, Figure 1 The start of this section is used as a programme switching cue point, and shall commence3s before programme. It is essential that true video black level and audio silence,(0000H in16-bit2s complement form for digital audio), are maintained during this period. 3.4 Programme
34、 start Section D, Figure 1 The programme shall commence3 0,1s after the cue point in3.3, but it is not mandatory for the sound and vision to start simultaneously. 4 Trailer Section E, Figure 1 After completion of the programme, black-burst signal and silence shall be recorded without interruption fo
35、r more than30s. This section shall be defined as the trailer. EN 60574-21:1993 4 BSI 12-1999 NOTEThe video part of the tape may include F.M. or P.C.M. audio signals, which should be muted during the3-second interval between the cue-point and the start-point. Figure 1 Diagram showing the signals reco
36、rded on the leader and trailer and the relevant timingsBSEN60574-21:1994 BSI 12-1999 National annex NA (informative) Committees responsible The United Kingdom participation in the preparation of this European Standard was entrusted by the Electronic Equipment Standards Policy Committee (EEL/-) to Te
37、chnical Committee EEL/32, upon which the following bodies were represented: Association of British Theatre Technicians Audio Engineering Society British Broadcasting Corporation British Educational Suppliers Association British Kinematograph, Sound and Television Society British Radio and Electronic
38、 Equipment Manufacturers Association British Telecommunications plc Consumers Association Electronic Components Industry Federation Federation of British Audio Independent Television Association Institution of Electrical Engineers International Association of Broadcasting Manufacturers National Coun
39、cil for Educational Technology (NCET) Professional Lighting and Sound Association Radio Electrical and Television Retailers Association Royal Institute of British Architects Royal National Institute for Deaf People Society of Cable Television Engineers Sound and Communication Industries Federation T
40、he Association of Electronics, Telecommunications and Business Equipment Industries (EEA)BS EN 60574-21:1994 BS5817-21: 1994 IEC574-21: 1992 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It pre
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