This standard specifies the position and dimensions of the picture and optical soundtrack on the release prints of 35mm motion pictures with non-anamorphic picture and anamorphic picture with a lateral compression ratio of 2:1 and a screen aspect ratio of 1:2.35, as well as the size and position of the stimulus light blade. GB/T 4638-1997 Position and dimensions of the picture and optical soundtrack on the release prints
of 35mm motion pictures with non-anamorphic picture and anamorphic picture with a lateral compression ratio of 2:1 and a screen aspect ratio of 1:2.35. GB/T 4638-1997 Position and dimensions of the picture and optical soundtrack on the release prints of 35mm motion pictures with non-anamorphic picture and anamorphic picture with a lateral compression ratio of 2:1 and a screen aspect ratio of 1:2.35, as well as the size and position of the stimulus light blade.

GB/T4638\u20141997
This standard is a revision of GB4638\u201484 based on ISO2939:1986. This standard is equivalent to ISO2939:1986 in terms of technical content and writing rules.
GB4638-84 is formulated with reference to the international standard ISO2939:1975 "Position and size of pictures and optical soundtracks on 35mm film distribution copies".
In 1986, ISO/TC36 revised ISO2939:1975. The revised standard ISO2939:1986 made technical modifications to Section 2.3 of the original standard.
After this revision, GB4638 added the provisions on the positional relationship between the picture and the corresponding optical soundtrack on the 35mm film distribution copy in the film projection operation, as well as detailed film loading instructions to ensure the fast-forward effect of sound and sound synchronization in the theater audience seats. In addition, this standard restores the maximum limit of the screen aspect ratio of the distribution copy of the masked film from 1.66:1 to 1.85:1 in accordance with the international standard.
This standard will be implemented from June 28, 1998. All draft standards submitted for approval from the date of implementation shall comply with the provisions of this standard. From the month of implementation, this standard will replace GB4638-84. This standard was proposed by the Ministry of Radio, Film and Television of the People's Republic of China. This standard is under the jurisdiction of the China Film Science and Technology Research Institute of the Ministry of Radio, Film and Television. This standard was drafted by the China Film Science and Technology Research Institute of the Ministry of Radio, Film and Television. The drafter of this standard is Sun Yanwei.
CB/T4638-1997
ISO Foreword
ISO (International Organization for Standardization) is a worldwide federation of national standards associations (ISU member bodies). The development of various international standards is completed by ISO technical committees. Any member body interested in the topic being studied and discussed by an existing technical committee has the right to select representatives to join the committee. Official and non-official international organizations in liaison with ISO may also participate in this work. All draft international standards adopted by the technical committee shall be circulated to the member bodies for comments before being approved as international standards by the ISO Council. According to the relevant ISO procedures, at least 75% of the members must vote in favor for the standard to be approved. International Standard ISO2939 was prepared by ISO/TC36 (Film) Technical Committee. This standard is the first edition and cancels and replaces the original first edition (15) 2939:1975). The technical content of Sections 2 and 3 of the second edition has been changed.
Users should be reminded that all international standards are subject to gradual revision over time. Therefore, the referenced standards listed in this document and any other international standards refer to the latest published versions unless otherwise specified. 1 Scope
National Standard of the People's Republic of China
Plcture image area and photographic sound record on 35 mm motion-picture release prints-Position and dimensions
GB/T4638\u20141997
eqxISO 2939:1986
Replaces GB/T 4638--84
This standard specifies the position and dimensions of the picture and optical sound track on 35 mm motion-picture release prints of non-anamorphic pictures and anamorphic pictures with a horizontal compression ratio of 2:1 and a screen aspect ratio of 1:2.35, as well as the dimensions and position of the excitation light blade. 2 Dimensions
2.1 The dimensions are shown in Figure 1 and Table 1 below. D
Light source directionbzxZ.net
Axis position of the face
Centre line of the production trace
(The film shown in the figure is viewed from the projector light source, with the emulsion side facing the observer) Figure 1
National Technical Supervision High Court Approved by
Jiajin on 1997-06-28
Film running direction
EF- 0. 25 mm, K and I, should be approximately equal. 1998-03-01 Implementation
B(reference value)
C(rated value)
D(minimum value)
Reference value (see Note 1)
H(Note 2)
H(see Note 3)
G4/T 4638\u20141997
7. 80-8 1
16. 00 9 3
1G. 50 Maximum
12.80 Minimum
J(see Note 4)
N(maximum vertical)
R(maximum value)
1 For anamorphic screens, with a screen aspect ratio of 2.35\u00b7. 2 For non-anamorphic screens, with a screen aspect ratio of 1.3711. Dimensions
1.93-0.8
6.17-0.08
6.10-0.03
3 For non-anamorphic images with aspect ratios up to 1.85:1 (including 1.66:1 for anamorphic films). 4 For anamorphic optical soundtracks.
2.2 All dimensions are given for unrecorded film. 2.3 For optical soundtracks on copies, the center of the corresponding frame in the normal projection room is 21 \u00b1 1/2 frames ahead, mm
. For 35mm film copies, the frame for the optical soundtrack to synchronize sound and picture is 21 = 1/2 frames. In a normal movie projection in a cinema, since the speed of sound propagation in the air is lower than the speed of light, if the audience sitting in the center of the cinema seat area wants to feel the synchronization of sound and screen, the sound should appear on the screen before the corresponding picture. Generally, the distance between the center of the cinema seat area and the screen is about 15 degrees. The time it takes for the sound wave to pass through this distance is equivalent to the time required for the copy to run one frame. For this reason, ISO4241 stipulates that in the head of the optically produced 35mm film distribution, the "sound head" is 20 frames ahead of the film gate, that is, 21 frames minus 1 frame.
3 Technical performance
The frames between the frames on the film copy, the interval between the frames and the sound track, and the sound track and the perforation should all be opaque. 4 Examination Standards
SU 70 Cinemagraphs \u2014 Mono 35 mm motion picture negative soundtrack position and maximum width dimensions IS0 491 Cinemagraphs \u2014 35 mm film and magnetic film \u2014 Cutting dimensions IS0 2906 Cinemagraphs \u2014 Picture area formed by the film window of a 35 mm motion picture camera on the film stock \u2014 Position and dimensions
IS0 2907 Cinemagraphs \u2014 Maximum projectable picture area on 35 mm motion picture film \u2014 Position and dimensions IS0 4241 Cinemagraphs \u2014 Title and trailer for 35 mm and 16 mm motion picture release prints \u2014 Technical requirements
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