Overview
ISO 7739:2016 is an international standard focusing on cinematography and the specifications of two-track photographic analogue sound records on 16 mm motion-picture prints. This standard defines the lateral positions and width dimensions of two-track variable area sound recordings, ensuring precise placement and size consistency across 16 mm prints. In addition, ISO 7739:2016 specifies the area scanned by the sound reproducer, which is crucial for accurate sound playback.
This standard replaces the earlier 1983 edition with minor revisions and is essential for filmmakers, film processors, projector manufacturers, and archivists who work with analogue soundtracks on motion-picture films.
Key Topics
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Sound Track Positioning and Dimensions
The standard lays down exact measurements and lateral positions for the two variable area sound tracks on 16 mm prints, as well as the reference edge alignment. This ensures compatibility and quality in both recording and playback.
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Sound Record Characteristics
- Channel 1 and Channel 2 sound tracks must be positioned in line perpendicular (90° ± 5’) to the film's reference edge.
- Channel 2 sound record is always nearest the outer edge of the film.
- The septum (separator) between two tracks must be opaque to prevent crosstalk. Minor variations caused by printing are acceptable.
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Picture-Sound Displacement
The relative displacement between the picture and sound tracks follows the specifications set in ISO 4243, ensuring synchronization between audio and moving images.
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Track Usage & Channel Assignment
The two tracks can carry either related stereophonic sound or unrelated audio programs. For stereophonic material, Track 1 corresponds to the left channel, and Track 2 to the right channel (viewed from the auditorium). This facilitates accurate multi-channel sound reproduction.
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Crosstalk and Guard Bands
ISO 7739:2016 recommends minimum crosstalk levels-20 dB for stereophonic and 26 dB for unrelated material-to avoid interference between channels while maximizing usable sound track area.
Applications
ISO 7739:2016 is vital for several practical applications in the film and audio industries:
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Film Production & Distribution
It guides producers and distributors in creating 16 mm prints with standardized sound track placement, enabling seamless playback in various cinemas worldwide.
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Projector and Playback Equipment Design
Manufacturers rely on this standard to design sound reproducers and projectors that accurately scan the two-track sound area with minimal crosstalk, ensuring high-quality audio fidelity.
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Archiving and Restoration
Archives preserving 16 mm film prints use ISO 7739:2016 to identify and maintain sound track standards, crucial for digital transfers and restoration projects.
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Stereophonic Audio Implementation
Facilities implementing stereo sound reproduction in cinemas use the track allocation guidelines for proper speaker configuration and channel mapping.
Related Standards
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ISO 4243: Specifies the picture image area and positions of photographic sound records on 16 mm motion-picture release prints, providing complementary details on picture-sound displacement and general film frame layout.
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ISO/IEC Directives, Part 1 & 2: Outline the procedures for drafting and maintaining ISO standards, ensuring consistent quality and editorial rules compliance evident in ISO 7739:2016.
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Other Cinematography Sound Standards: Various international standards cover analogue and digital sound recording formats on different film gauges to ensure cross-compatible cinematic audio.
Summary
ISO 7739:2016 offers comprehensive specifications for the precise positioning and dimensioning of two-track analogue sound on 16 mm motion-picture prints. By adhering to this standard, the cinematography industry maintains consistent sound quality, accurate channel separation, and effective reproduction compatibility in analogue film presentation. This standard is critical for filmmakers, cinema operators, and equipment manufacturers aiming for superior analogue sound experiences in 16 mm film projection.