SMPTE ST 112-2004 Motion-Picture Film (16-mm) - 100-Mil Magnetic Audio Record.pdf

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1、 1 Scope 1.1 This standard specifies the position, dimensions, and reproducing speed of the nominal 100-mil (2.54-mm) magnetic audio record on 16-mm motion-picture film. 1.2 This standard also specifies the longitudinal picture-audio displacement on the film. 2 Audio record 2.1 The lateral location

2、and width of the magnetic audio record shall be as specified 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 5 to the reference edge of the film. 2.3 With the direction of travel as shown in figure 1, the magnetic coating is on the surf

3、ace toward the observer. 3 Reproducing speed The recording shall be made so that the audio record will reproduce properly at 24 perforations per second (approximately 36 ft 11 m per minute or 7.2 in 183 mm per second) which is 24 frames per second. 4 Longitudinal picture-audio displacement The magne

4、tic audio record on the film shall precede the center of the corresponding picture by a distance of 28 frames frame (see annex A.5). Page 1 of 3 pages SMPTE 112-2004 Revision of SMPTE 112-1999 SMPTE STANDARD for Motion-Picture Film (16-mm) 100-Mil Magnetic Audio Record Copyright 2004 by THE SOCIETY

5、OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved November 8, 2004 SMPTE 112-2004 Page 2 of 3 pages Figure 1 Lateral location and width of magnetic audio record Table 1 Specifications Dimensions Inches Millimeters A 0.573 0.002 14.55 0.0

6、5 B 0.085 0.004 2.16 0.10 C 0.628 ref 15.95 ref SMPTE 112-2004 Page 3 of 3 pages Annex A (informative) Additional data A.1 Record width 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

7、 is narrower than the width of the coating 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 measur

8、ed indirectly by measuring the gap width and 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 m to 15 m). If the recording head is unavailable, the recorded record may be made visible by the use of a carbonyl

9、iron suspension. Care should be taken to apply the minimum quantity that makes the recording visible, so that the developed image is not wider than the actual recorded area. A.2 Recording head gap width The recommended recording head gap width is 0.085 in 0.004 in (2.16 mm 0.10 mm). Combination reco

10、rd-reproduce heads should also have a gap width of 0.085 in (2.16 mm). A.3 Reproducing the head gap width If precision measurements or calibrations are to be made in accordance with this standard, reproducing head gaps of the same width dimension or wider than the recorded track must be used to take

11、 into account edge effects or fringing. A.4 Basic standards Motion-picture prints conforming to this standard are usually made on film manufactured in accordance with SMPTE 109, magnetically striped in accordance with ANSI/SMPTE 87M, which specifies the minimum striping width as 0.095 in (2.41 mm),

12、and projected in accordance with SMPTE 233. A.5 Longitudinal picture-audio displacement As a working procedure, the accuracy of picture-audio displacement in a projection print is frequently judged by screening in a review room. It is important that the standard thread-path in this review room proje

13、ctor be set accurately to the value specified in this standard minus 1 frame for every 50 ft (15 m) separating the loudspeaker from the observer. Otherwise, nonstandard prints may be produced. A.6 Audio record position The centerline, dimension A, of the magnetic record may be determined only by the

14、 measurement of the record position relative to the reference edge. This derived centerline is a very useful dimension assisting interchangeability among various recorders and reproducers. Annex B (informative) Bibliography ANSI/SMPTE 87M-1996, Motion-Picture Film (16-mm) 100-Mil Magnetic Striping SMPTE 109-2003, Motion-Picture Film (16-mm) Perforated 1R and 2R SMPTE 233-2003, Motion-Picture Film (16-mm) Projectable Image Area and Projector Usage