1、 STD-SMPTE 25bM-ENGL L97b 8357401 0002b4b ?Li7 W SMPTE STANDARD for Television - Specifications for Video Tape Leader ANSVSMPTE 256M-1996 Revision of ANSIISMPTE 256M-1991 Page 1 of 4 pages 1 Scope 3 Runup section 1.1 This standard specifies the minimum re- quirements for the content and duration of
2、Sig- nals recorded prior to the start of the recorded program material to permit setup and adjustment of equipment for optimum performance during reproduction. In video tape systems which do not employ a tape cassette, there shall be a 10-second minimum dura- tion runup section of blank tape (see fi
3、gure l (A) prior to the recording of any signals on the tape. 4 Noise reduction 1.2 The standard also specifies a visual and aural countdown sequence to facilitate program cuing and specifies the duration of video tape that precedes and follows the recorded material to provide the minimum lengths of
4、 tape required to ensure proper threading in video tape systems which do not employ tape cassettes. -k+ -L 2 Normative references This segment of the video tape leader shall be used only if an external audio noise-reduction encoding system, not inherent to the video tape format being used, is applie
5、d to the program audio material and decoding is required during the playback. The use of external audio noise reduction is not covered by SMPTE specifications, and must be by mutual agree- ment. The tape shall be labelled with information about the form of external audio noise reduction used. The fo
6、llowing standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the
7、 possibility of applying the most recent edition of the standards listed below: 4.2 Audio 4.1 Video Avideo Signal as specified in 5.1 shall be recorded in this video segment (See figure for a duration equal to the total duration Of the audio signals speci- fied in 42.1 and 42.2. EIA-l89-A, Encoded C
8、olor Bar Signal 4.2.1 Noise-reduction identification An interrupted tone of 5-second minimum duration 1 (C) at the level and frequency specified in 5.2.1. The SMPTE EG 1-1990, Alignment Bar Test Signal shall be recorded in this audio segment (see figure for Television Picture Monitors interruptions
9、may be of any duration and frequency that will be observed or heard by the operator during playback, nominally of 1 -second duration at 1 -second SMPTE RP 142-1 993, Stereo Audio Track Allocations and Identification of Noise Reduction for Video Tape Recording intervals. CAUTION NOTICE: This Standard
10、 may be revised or withdrawn at any time. The procedures of the Standard Developer require tha1 action be taken to reaffirm, revise, or withdraw this standard no Later than five years from the date of publication. Purchasers ot standards may receive current information on ail standards by calling or
11、 writing the Standard Developer. Printed in USA. Copyright O 1996 by THE SOCIETY OF L American Nalianal Standard MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdaie Ave., White Plains, NY 10607 (914)761-1100 Approved December 3,1996 STD-SMPTE 25bfl-ENGL 177b (BI Signal n 3 c Color Bar (when aud
12、io NR 1s used) d n ANSVCMPTE 256M-1996 (1 3% $ Signal g“1 coa s Color Bar oz VIE W 4.2.2 Noise-reduction alignment If the external audio noise-reduction system being used requires an alignment signal or signals, they shall be recorded in this audio segment (see figure 1 (D) for a minimum of 30 secon
13、ds. This signal must not be recorded unless the noise-reduction identifica- tion specified in 4.2.1 is also recorded. 4.3 Leader noise reduction If an extemal audio noise-reduction encoding system is used for the program material, the audio signals specified in 5.2 should be recorded without externa
14、l audio noise-reduction encoding whenever practical. 5 Basic leader 5.1 Video 5.1.1 Color bar signal Acolor bar pattern as defined by EIA-189-Aor SMPTE EG 1 shall be recorded in this video segment (see figure 1 (E) for a duration equal to the total duration & of the audio signals specified in 5.2.1,
15、5.2.2, and 5.2.3. Color bar signals shall be recorded with maximum luminance at 77 IRE units corresponding to a 75% chroma level, and shall include a reference white bar and a reference black bar. The recording of the color bar signal shall be made under the same conditions of equipment adjustment a
16、s used for recording the program video material. For original recording, the color bar signal shall originate in and be fed through the same studio and equipment used for the program. In the case of monochrome recordings, a stair- step signal may be substituted for the color bar signal. 5.1.2 Slate
17、and countdown Visual identification information shall be recorded in this video segment (see figure 1(F) for a duration equal to the duration of the audio signals specified in 5.2.4. The identification shall contain the following information (if known): 1) title 2) subject 3) production number - Dir
18、ection of tape travel rrl I 1 10s I 10s I Segment iZnlj-2 min min times 35s 50s I : I min min t bb NOTE - See 5.2.2 for content of this audio segment. Figure 1 - Video tape leader Page 2 of 4 pages . STD-SMPTE 25bM-ENGL 377b 4) take number 5) name of recording studio 6) date of recording 7) broadcas
19、t date In addition, a visual seconds countdown shall be recorded in this video segment, beginning with the number representing the seconds remaining until the start of program, decreasing with each elapsed sec- ond, and ending with the number 2. Each visual countdown number shall appear coincident w
20、ith the beginning of the corresponding tone burst specified in 5.2.4 and shall remain until the beginning of the next tone burst, with the exception of the number 2, which shall appear for a single video frame beginning 2 seconds before the program start. 5.1.3 Black A video black signal (sync, colo
21、r burst, and setup) shall be recorded in this video segment (see figure 1 (G), beginning with the video frame following the countdown number 2 and ending with the video frame preceding the start of program. 5.2 Audio 3 5.2.1 Setup tone An audio setup tone shall be orded in this audio segment (seefig
22、ure l(H) for a minimum of 30 sec- onds. The tone shall consist of a sine wave of a single frequency between 400 Hz (nominal) and 1000 Hz (nominal) at a level matching the operating level of the 8357403 0002b11 7LT H ANSUSMPTE 2561-1 996 program material (normally reference level flux for the tape fo
23、rmat being used). The tone recorded on all audio tracks shall originate from the same oscillator and be coherent in phase on all audio tracks. 5.2.2 Channel identification 5.2.2.1 Monophonic audio recording When the program audio is a monophonic recording, the audio setup tone specified in 5.2.1 sha
24、ll continue on all audio tracks in this audio segment (see figure 1 (I) for a 1 O-second nominal duration. 5.2.2.2 Stereophonic audio recording When the program audio is a stereophonic recording, a sequence of audio tones of frequency and level as specified in 5.2.1 shall be recorded in this audio s
25、egment (see figure l(1) for a 10-second nominal duration. The pattern of this sequence of audio tones shall be as given in table 1. The exact duration of these tones is not critical providing there is a single burst of audible tone on the left channel followed by two bursts of audible tone on the ri
26、ght channel. The left and right channels are defined in SMPTE RP 142 and the individual recording format standards. 5.2.3 10 kHz A 1 O-kHz sine wave with the same input level as the signal specified in 5.2.1 shall be recorded on all tracks in this audio segment (see figure 1 (J) for a minimum of 1 O
27、 seconds. Table 1 - Sequence of audio tones for stereophonic audio channel identification Segment 1 Segment 2 Segment 3 Segment 4 Segment 5 Segment 6 Segment 7 Left channel Right channel Nominal duration Silence Silence 1.4 seconds Tone burst Silence 1.4 seconds Silence Silence 1.4 seconds Silence T
28、o ne burst 1.4 seconds Silence Silence 1.4 seconds Silence Tone bu rst 1.4 seconds Silence Silence 1.4 seconds Page 3 of 4 pages ANCVSMPTE 256M-1996 5 4 32 Black 5.2.4 Slate and countdown tone bursts Program A series of countdown tone bursts shall be recorded on all tracks in this audio segment (see
29、 figure 1 (K). The tone bursts shall be of a frequency and level as specified in 5.2.1, and shall each be of 1 video frame duration. The start of each tone burst shall be coinci- dent with the corresponding seconds transition before the program start (see figure 2). The tone bursts shall begin 8 or
30、more seconds preceding the program start and shall end with the tone burst 2 seconds before the program start. In addition, an aural recording of all or patt of the information in 5.1.2 may be recorded in this audio segment, but it shall not interfere with the intel- ligibility of the countdown tone
31、 bursts. 7 - d- m 4 CI a, al Silence e Silence Silence e 6 End hl I 2 2 t: O v) U N E s! 2 0 a -I a, l- Silence Program 2 6.1 Video A video black signal (sync, color burst, and setup) shall be recorded in this video segment (see figure 1 (M) for a minimum of 1 O seconds. 6.2 Audio Silence shall be r
32、ecorded on all tracks in this audio segment (see figure 1(N) for a minimum of 10 sec- onds. 7 Runout section 5.2.5 Silence Silence shall be recorded on all tracks in this audio segment (see figure 1 (L) from the end of the 2-sec- ond tone burst to the beginning of the program. - Direction of tape In
33、 video tape systems which do not employ a tape cassette, there shall be a 1 O second minimum dura- tion runout section of blank tape (see figure l(0) following the recording of all signals on the tape. travel A VIDEO Segment times in seconds Time from program start in seconds Duration in video frames AUDIO Figure 2 - Countdown signal alignment Page 4 of 4 pages
