SMPTE ST 6-1998 Video Recording - 2-in Quadruplex Tape - Video Audio and Tracking-Control Records.pdf

1、STD-SMPTE b-ENLL 1770 m 8357401 000311D O74 R SMPTE STANDARD for Video Recording - SMPTE 6-1998 Revision of ANCVCMPTE 6-1993 2-in Quadruplex Tape - Video, Audio and Tracki ng-Control Records 1 Scope This standard specifies both the locations for the edges of the video, audio, and tracking-control re

2、cords, and the mechanical separation of the simul- taneously recorded information of the video and audio records, as recorded at 15 and 7.5 ink on 2-in quad- ruplex video magnetic tape. 2 Definitions 2.1 transverse: Pertaining to dimensions or motions perpendicular to the tape travel. 2.2 longitudin

3、al: Pertaining to dimensions or motions parallel to the tape travel. 2.3 downstream: Pertaining to locations on the tape longitudinally displaced from a given reference point, in the direction of tape travel. 2.4 upstream: Pertaining to locations on the tape longitudinally displaced from a given ref

4、erence point, in the direction opposite to tape travel. I Page 1 of 4 pages 2.5 reference edge: On a video tape containing quadruplex-recorded information, that longitudi- nal tape edge nearest the tracking-control record. 2.6 trailing edge, video track The upstream edge of the video track. 2.7 tran

5、sverse reference line: A I i n e p e r p e n- dicular to the reference edge and passing through a video track trailing edge at its lowest end (point To) as in figure 1. 3 General 3.1 References The transverse reference line and reference edge shall be the references for all dimensions in this standa

6、rd. 3.2 Measurement conditions The dimensions specified in this standard are measured with no transverse or longitudinal tension applied to the tape (see annex A.4). TRAILING EDGE VIM0 TRACK TRACKING CONTROL -I RECORD TAPE TRAVEL t TRANSVERSE REFERENCE EDGE REFERENCE LINE Figure 1 - Definitions Copy

7、right B 1998 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Harisdale Ave., White Plains, NY 10607 (914) 761-1100 Approved September 17, 1998 STD-SMPTE b-ENGL 1998 CMPTE 6-1 998 3.3 Magnetic coating With the direction of tape travel as shown in all figures in this standard, the mag

8、netic coating is on the surface facing the observer. 4 Longitudinal dimensions 4.1 Average video track pitch For a tape recorded at 15 ink (381 mrrs), the longi- tudinal distance, R, from a transverse reference line to a point, T4, four tracks away (see figure 2), shall be greater than 0.062438 in (

9、1 58593 mm) and less than 0.062562 in (1.58907 mm). (An acceptable method for obtaining the accuracy required by the above dimensions is to measure the span occupied by 3072 tracks, which should be greater than 47.952 in (1217.98 mm) and less than 48.048 in (1220.42 mm).) See annexes A.2 and A.3. Fo

10、r a tape recorded at 7.5 ink (190.5 mm/s), the longitudinal distance from a transverse reference line to a point, T4, four tracks away shall be greater than 0.031 21 9 in (0.79296 mm) and less than 0.031 281 in (0.79454 mm). (An acceptable method for obtaining the accuracy required by the above dime

11、nsions is to measure the span occupied by 3072 tracks, which should be greater than 23.976 in (608.99 mm) and less than 24.024 in (610.21 mm).) See annexes A.2 and A.3. 4.2 Video track spacing The longitudinal distance from any transverse refer- ence line to points Ti, T2, and T3 shall be W4, W2, an

12、d 3R/4, respectively, with a tolerance of f 0.00015 in (0.0038 mm), where R is the average video track pitch as determined in 4.1 for the tape being measured (see figure 2). (The tolerance indicated cannot be readily measured on a prerecorded tape by methods presently available. At the present state

13、 of the art, these dimensions are controlled by the head wheel manufacturers ability to achieve coplanarity of the recording pole tips.) See annexes A.2 and A.3. 4.3 Video track curvature and angle The trailing edge of any video track shall fall between two parallel lines spaced apart by 0.001 in (0

14、.03 mm). For a tape recorded at 15 ink, the two parallel lines shall make, with the reference edge, a possible angle no greater than 90“ 36 and no less than 90“ 30, when positioned so as to enclose the entire length of the video track trailing edge. For a tape recorded at 7.5 ink, the two parallel l

15、ines shall make, with the reference edge, a possible angle no greater than 90“ 19 30“ and no less than 90“ 13 30, when positioned so as to enclose the entire length of the video track trailing edge. 4.4 Video track width For a tape recorded at 15 ink, the longitudinal width of any video track shall

16、lie between 0.0095 in (0.241 mm) and 0.01 05 in (0.267 mm), measured at any and all points along its transverse direction. For a tape recorded at 7.5 ir&, the video track width shall lie between 0.0050 in (0.127 mm) and 0.0060 in (0.152 mm). I 1 I I I AUDIO N0.I RECORD (PROGRAM AUDIO) AUDIO N.2 RECO

17、RD (CUE TRACK) I I I I 1 I n T , I I IC- SOUND RECORD RECORD II CORRESPONDING 1- CONTROL Figure 2 - Longitudinal dimensions Page 2 of 4 pages STDOSMPTE b-ENGL 1778 8357401 0003112 747 I SMPTE 6-1 998 4.5 Audio record displacement Audio or other information which is time-coincident with video informa

18、tion recorded at a point, T, of any video track shall be recorded in audio record No. 1 (Program audio) 01 audio rmd No. 2 (cue track), at a distance, L, downstream from that point, T, where L shall be at least 9.200 in (233.68 mm) and no more than 9.300 in (236.22 mm). 5 Transverse dimensions The t

19、ransverse dimensions shall be as specified in figure 3 and table 1. MON AURAL STEREO FULL TRACK (PROGRAM AUDIO) CONTROL REFERENCE EDGE OF TAPE A Figure 3 - Transverse dimensions Table 1 - Dimensions Inches Mi II imeterc Dimensions Minimum Maximum Minimum Maximum A 0.000 0.004 0.00 0.10 B C D E F G G

20、 H J K 0.040 0.058 0.078 0.087 1.902 1.921 1.920 1.945 1.965 1.988 0.049 0.062 0.085 0.094 1.914 1.930 1.928 1.951 1.971 1.996 1 .o2 1.47 1.98 2.21 48.31 48.79 48.77 49.40 49.91 50.50 1.24 1.57 2.16 2.39 48.62 49.02 48.97 49.56 50.06 50.70 Page 3 of 4 pages 6 Program audio (see figure 3) 6.1 Monaura

21、l recording mode The usual method for recording a monaural audio program shall be by means of a recording head pro- ducing an audio l pattern of dimensions G-K (full track) . 6.2 Stereo recording mode Recording of stereo shall be by means of a split recording head producing an audio 1 pattern of dim

22、en- sions G-H for track 1 (left) and J-K for track 2 (right). corded information of the video and audio records (see 4.59, the record/reproducer gaps of the two ste- reo program audio heads shall lie on a common straight line. 6.2.2 Relative polarity For stereo program material, the relative polarit

23、y of the audio signals at the inputs to a stereo television magnetic tape recorder shall be such that any mono- phonic component of the progam shall have the same polarity in the magnetic records of both channels. 6.2.3 Monaural program (while in stereo mode) 6.2.1 Program audio head position In add

24、ition to the required dimensions for the me- chanical separation of the simultaneously re- If there is to be only one audio program recorded by a machine with the stereo recording track record (of 6.2), then both tracks 1 and 2 shall be utilized for that single Program. Annex A (informative) Additio

25、nal data A.l A magnetic record is that area in which magnetization conveying the intended signal exists. A common technique for measurement of record locations and dimensions is the use of carbonyl iron to make them visible. A.2 Since all recorded tapes exhibit wow and flutter to some degree, the sp

26、an of measured tracks should be long enough to average out variations in video track pitch arising from wow or flutter, If other measuring methods are employed, appropriate averaging must be included in the measure- ment. A.3 The track pattern specified in 4.1 and 4.2 results when the tape speed in

27、inches per second and the head wheel rotational rate in revolutions per second are in the ratio of 0.0625:l for 15 ink recording prctice, and in the ratio of 0.03125:l for 7.5 ink recording practice. Since both the head wheel rotational speed and the capstan metering rate are locked to the televisio

28、n frame rate, the speed of the tape will vary with the television frame rate. This speed variation will not alter the pattern placed on the tape. Replay rate of any recording, as well as the replay rate of the information contained in the record, will be determined solely by the reference frequency

29、to which the replay capstan and head wheel are synchronized. Annex B (informative) Bibliography Primary causes of departures from the video track pitch specified in 4.1 are incorrect capstan diameter, capstan slippage, and incorrect longitudinal tape stretch. The tolerances specified in 4.1 reflect

30、the magnitude of allowable changes in the ratio of tape speed to head wheel rotational speed. Variations in excess of those specified will not only result in improper video track pitch, but will also result in an incorrectly placed control track on tapes re- corded on machines having the control tra

31、ck head displaced from the plane of rotation of the video pole tips by approxi- mately 0.7 in (1 8 mm), as is common practice in present-day transports. (See SMPTE RP 16 for a description of the tracking-control record.) A.4 Although, with sufficient care, measurements of track dimensions may be mad

32、e with no transverse or longitudinal tension applied to the tape, tape-handling problems during measurements may be lessened by making two sets of measurements at two different longitudinal tensions and extrapolating data thus obtained to the zero-tension condition. A.5 Current technology restricts the application of this standard to those applications, such as stereo, which can tolerate a moderate amount of crosstalk between channels or tracks. SMPTE RP 16-1993 (R1997), Specifications of Tracking Control Record for 2-in Quadruplex Video Magnetic Tape Recordings Page 4 of 4 pages