1、SMPTE 208M 92 m 8357403 0000845 T98 ANSI/SMPTE 208M-1992 Revision, redesignation and consolidation of and ANSI PH22.208M-1984 ANSIISMPTE 213M-1984 SMPTE STANDARD e for Motion-Picture Film - 35- and 16-mm Magnetic Audio Records - Recorded Characteristics 1 Scope This standard specifies the recorded c
2、haracteristics of magnetic records on 35-mm motion-picture film intended for reproduction at 24 frames per second, and on 16-mm motion-picture film intended for repro- duction at 24 frames per second. (See notes 1 and 2.) 2 Recorded characteristics With a constant-amplitude sine-wave signal applied
3、to the input of the recording system, the nominal characteristic of the short circuit magnetic flux versus frequency shall decrease with increasing frequency proportionately to the impedance of a parallel combi- nation of a capacitance and a resistance having the time constant z = 35 ps for 35-mm mo
4、tion-picture film, and the time constant z = 70 ps for 16-mm motion-pic- ture film. (See note 3.) a The characteristics defined above are represented by the following equation: where LQ is the recorded relative short circuit mag- netic flux level in decibels, f is the frequency in hertz, z is the ti
5、me constant described above, and is a constant calculated to make b = O at the reference frequency of 1 kHz for 35-mm motion-picture film, and to make b = O at the reference frequency of 400 Hz for 16-mm motion-picture film: for 35-mm film for 16-mm film Lo = 0.2051 1 O. 13238 Approximate numerical
6、values for each curve are given in table 1, Page 1 of 2 pages Table 1 - Recorded characteristics Frequency MZ 20 31.5 40 50 63 80 1 O0 125 160 200 250 31 5 400 500 630 800 1 O00 1250 1600 2000 2500 3150 4000 5000 6300 8000 1 O000 12500 14000 16000 20000 Relative 35-mm film 35 ys 0.20 0.20 0.20 0.20
7、0.20 0.20 0.20 0.20 0.20 0.20 0.19 0.1 8 0.1 7 0.1 5 0.1 2 0.07 0.00 -0.1 1 -0.30 -0.56 -0.94 -1 -50 -2.28 -3.24 -4.45 -5.92 -7.46 -9.12 -1 0.00 -1 1 .O6 -1 2.88 ?vel, dB 16-mm film 70 ys 0.13 0.13 0.13 0.13 0.13 0.12 0.12 0.1 1 0.10 0.08 0.05 0.00 -0.07 -0.1 9 -0.37 -0.64 -1 .o1 -1.61 -2.36 -3.31 -
8、4.52 -5.99 -7.53 -9.25 -11.13 -12.95 -14.81 -1 5.77 -1 6.90 CAUTION NOTICE: This Standard may be revised or withdrawn at any time. The procedures of the Standard Developer require that action be taken to reaffirm, revise, or withdraw this Standard no later than five years from the date of publicatio
9、n. Purchasers of standards may receive current information on all standards by calling or writing the Standard Developer. Printed in USA. Copyright01992 byTHESOCIETYOF L American National Standard MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdah Ave., White Mains, NY 10607 (914) 761-1 100 App
10、roved November 12,1992 ANSI/SMPTE 208M-1992 3 Tolerances 2 The film velocity of 16-mm film is also commonly stated as 7.2 inches Der second or 183 millimeters Der second, and historically stated as 36 feet or 1 I meters per minute. Magnetic audio records on motion-picture film shall be recorded to t
11、he characteristics specified in clause 2 with the tolerances shown in figure 1 for 35-mm magnetic audio records, and with the tolerances shown in figure 2 for 16-mm magnetic audio records. 3 The time constant is only a convenience in defining the desired response curve and is never intended as a rec
12、om- mended electrical circuit. NOTES 4 This standard has substantiallv the same technical con- tent as that of IS0 1 188:1984 ani IS0 1 189:1986. 1 The film velocity of 35-mm film is also commonly stated as 18 inches per second or 457 millimeters per second, and historically stated as 90 feet or 27
13、meters per minute. n U a, c a, -3 -4 -5 20 3 n U a, S a, -3 -4 -5 m2 VI O 0 -1 y -2 - 31.5 63 125 250 500 lk 2k 4k 8k 6k 20k Frequency (Hz) Figure 1 - Tolerance on 35-mm recorded records 20 31.5 63 125 250 500 lk 2k 4k 8k 6k 20k Frequency (Hz) Figure 2 - Tolerance on 16-mm recorded records Annex A (
14、informative) Bibliography IS0 11 88:l 984, Cinematography - Recorded Characteris- tic for Magnetic Sound on Full-Coat 16 mm Motion-Picture Film - Specifications IS0 1189:1986, Cinematography - Recorded Characteris- tic for Magnetic Sound Records on 35 mm Motion-Picture Film Excluding Striped Release Prints - Specifications Page 2 of 2 pages
