1、SMPTE STANDARD for Motion-Picture Film (1 6-mm) - 200-Mil Center-Position Magnetic Audio Record ANSVSMPTE 218M-1996 Revision of ANSI/SMPTE 218M-1991 1 Scope This standard specifies the position, dimensions, and reproducing speed of the nominal 5.08-mm (0.200-in) center-position magnetic audio record
2、 on 16-mm mo- tion-picture film. 2 Audio record 2.1 The lateral location and width of the center- position magnetic audio record shall be as speci- fied in figure 1 and table 1. 2.2 The recording shall be made so that the azimuth of the record is at an angle of 90“ f 3 to the reference edge of the f
3、ilm. 2.3 With the direction of travel as shown in figure 1, the magnetic coating is on the surface toward the observer. 3 Reproducing speed Page 1 of 2 pages DIRECTION OF FILM TRAVEL Figure 1 - Center-position audio record Table 1 - Specifications The recording shall be made so that the audio record
4、 1 Dirneiions ,;iirete; o.628 Inches ref will reproduce properly at 24 perforations per second + 0.05 i- 0.002 alternate reproducing speed may be 25 frames per 7.98 & 0.05 0.314 f 0.002 second. (approximately 11 m 36 ft per minute or 183 mm 7.2 in per second) which is 24 frames per second. An 5.08 -
5、 0.00 0.200 - 0,000 CAUTION NOTICE: This Standard may be revised or withdrawn at any time. The procedures of the Standard Developer require that action be taken lo reaffirm, ravise, or withdraw this standard no later than five years from the date of publication. Purchasers of standards may receive c
6、urrent information on all standards by calling or writing lhe Standard DeveloDer. Printed in USA. Copyright 1996 by THE SOCIETY OF - American National Slandard MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Harlsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved April 8,1996 SMPTE 23BM 96 = 8
7、357403 O002349 043 ANSVSMPTE 218M-1996 Annex A (informative) Additional data A.l Recordwidth The width of the recorded area must be measured with great care as it enters directly into the calculation of flux per unit track width. When the recording head gap is narrower than the width of the coating
8、or stripe, as is normal for all motion-picture test films, there is a measurement complication involving both the uncertainties in seeing the track and in determining the recording fringing. If the recording head is available, the track width is best measured indirectly by measuring the gap width an
9、d adding to this dimension twice the thickness of the test record magnetic coating. This correction will usually be 0.0003 in to 0.0006 in (8 bm to 15 pm). If the recording head is unavailable, the recorded record may be made visible by the use of a carbonyl iron suspen- sion. Care should be taken t
10、o apply the minimum quantity that makes the recording visible, so that the developed image is not wider than the actual recorded area. A.2 Reproducing head gap width If precision measurements or calibrations are to be made on magnetic audio records made in accordance with this stand- ard, reproducin
11、g head gaps of the same width dimension or Annex B (informative) Bibliography ANSVSMPTE 109-1992, Motion-Picture Film (16-mm) - Perforated 1 R and 2R wider than the recorded track must be used to prevent edge effects or fringing. A.3 Erase heads Erasing head gaps used to erase the records specified
12、in this standard should be substantially wider than the record specified. A.4 Film base The film base used for the audio records conforming to this standard is usually made in accordance with ANSI/SMPTE 109. A.5 Picture-audio synchronization The film is used for audio records only. Any accompanying
13、picture is on a separate photographic film. When audio records are intended to be used in synchronization with pictorial material found on a separate film, the picture-audio relationship should be in accordance with SMPTE RP 25. A.6 Magnetic coating The dimensions of the magnetic coating are not specified, but it is assumed to be wide enough to permit placement of the audio records in accordance with this standard. SMPTE RP 25-1995, Audio and Picture Synchronization on Motion-Picture Film Relative to the Universal Leader for Magnetic and Photographic Records Page 2 of 2 pages
