1、 3404583 OLOOLO2 298 EUROPEAN STANDARD EN 60574-21 NORME EUROPENNE EUROPISCHE NORM December 1993 UDC 621.397.13:621.397.4:37 1.333 Descriptors: Electroacoustic equipment, recording apparatus, video recording, television systems, video signals, adjustment, specifications, identification English versi
2、on 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 -anlagen Partie 21: Amorce et fin de bande vido utilise pour lenseignement et la form
3、ation Audiovisuelle, Video- und Fernsehgerte und Teil 2 1 : Videoband-Vorspann und -Nachspann fr Lehr- und bungszwecke professionnelle (IEC 574-21 1992) (CEI574-21 : 1992) This European Standard was approved by CENELEC on 1993-12-08. CENELEC members are bound to comply with the CENKENELEC Internal R
4、egulations 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.
5、 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 me
6、mbers 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. CENELEC European Committee for Electrotechnical Standardization Comit
7、Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels O 1993 Copyright reserved to CENELEC members Ref. No. EN 60574-21 : 1993 E m 3404583 0II00II03 II24 m Page 2 EN 6057421 : 1993 Foreword The CENELEC ques
8、tionnaire procedure, performed for finding out whether or not the International Standard IEC 574-21 : 1992 could be accepted without textual changes, has shown that no common modifications were necessary for the acceptance as European Standard. The reference document was submitted to the CENELEC mem
9、bers for formal vote and was approved by CENELEC as EN 60574-21 on 8 December 1993. 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) 1995-03-15 3404583 OLOOLO4 Ob0 = Pag
10、e 3 EN 6067421 : 1993 AUDIOVISUAL, VIDEO AND TELEVISION EQUIPMENT AND SYSTEMS Part 21 : Video tape leader and trailer for education and training applications 1 Scope 1.1 This part of IEC 574 specifies the minimum requirements for recordings on the leaders and trailers of video recordings to assist u
11、sers to adjust equipment for optimum performance prior to the start of recorded programme material. It also specifies the audio and video information that precedes and follows the recorded programme material to ensure proper identification of the programme and to allow proper cueTup of and exit from
12、 the programme. 1.2 the measurement of the performance of a system. The signals recorded on the leaders and trailers are not intended as test signals for 2 Content 2.1 figure 1. A diagram representing the signals and timings on the leader and trailer is given in 2.2 The leader shall contain video an
13、d analogue or digital audio alignment signals for at least 30 s, and preferably for 60 s, to enable the display equipment to be set 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 f
14、ollowed by programme identification for approximately 12 s, followed by 3 s of black burst and silence, prior to the start of the programme. 3 Speciffcation of signais 3.1 Leader for adjustments - Section A, figure I 3.1.1 Video signal: Colour bars should be recorded for at least 30 s. The compositi
15、on 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): A frequency of approximately 1 O00 Hz may be used for the tone signal, which may be of the same duration as the bars specified in 3.1.1. The level should be at
16、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 tape recorder. 3404583 OLOOLOS TT7 D Page 4 EN 6067421 : 1993 Audio 1 and 2 should carry the same signal in phase, and for stereo the left-hand signal may b
17、e identified by signal interruption of approximately 0,25 s, every 3 s or by recording the left-hand signal only for at least 15 s followed by both left and right for 15 s. NOTE - A frequency of approximately 400 Hz may be used for analogue audio signals. 3.2 Programme identification - Section 6, fi
18、gure I 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 nominally 12 s, but shall cut to black at 3 f 0,l s before the programme starts. 3.2.2 The audio channel may contain a statement of the pro
19、gramme title and/or a short audio signal of one-second intervals to provide a Count-down. These signals shall finish as the video signal in 3.2.1 cuts to black 3 s before the programme starts. 3.3 Black burst and silence - Section C, figure I The start of this section is used as a programme switchin
20、g cue point, and shall commence 3 s before programme. it is essential that true video black level and audio silence, (OOOOH in 16-bit 2s complement form for digital audio), are maintained during this period. 3.4 Programme start - Section D, figure I The programme shall commence 3 f 0,1 s after the c
21、ue point in 3.3, but it is not mandatory for the sound and vision to start simultaneously. I I 4 Trailer - Section E, figure 1 After completion of the programme, black-burst signal and silence shall be recorded without interruption for more than 30 s. This section shall be defined as the trailer. w o V rn c O o o v) .- - 340q583 OLOOLOb 933 m Page 6 EN 6057421 : 1993 - C O Q .- G Io - .- c - E E L L n o, L n Q 1 O O o L - $ z Q c - .- - .J a U c Q c. C O .- : .- =o .- E o u o, L E c O O o E 0 ic I W 2 O
