Overview
ISO 26428-11:2011, titled Digital Cinema (D-cinema) Distribution Master - Part 11: Additional Frame Rates, is an international standard developed by ISO to define supplementary frame rates for digital cinema content delivery. Supplementing the primary frame rates of 24 and 48 frames per second (fps), this standard specifies additional frame rates of 25, 30, 50, and 60 fps. These are established to maintain the artistic intent of content producers during digital cinema distribution, ensuring accurate and consistent playback.
Developed in cooperation with the Society of Motion Picture and Television Engineers (SMPTE), ISO 26428-11:2011 supports extended use of digital cinema technologies by defining technical parameters for these additional frame rates, including the corresponding image characteristics and audio sample rates per edit unit. This facilitates compatibility and interoperability within the digital cinema ecosystem.
Key Topics
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Additional Frame Rates: The standard defines four new frame rates beyond the primary 24 and 48 fps. These frame rates are 25, 30, 50, and 60 fps.
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AFR Levels: Additional Frame Rate (AFR) levels are specified to align maximum horizontal and vertical pixel dimensions with each additional frame rate, forming a structured system for implementation:
- AFR Level 1: 4096 x 2160 pixels at 25 fps
- AFR Level 2: 2048 x 1080 pixels at 25 fps
- AFR Level 3: 4096 x 2160 pixels at 30 fps
- AFR Level 4: 2048 x 1080 pixels at 30 fps
- AFR Level 5: 2048 x 1080 pixels at 50 fps
- AFR Level 6: 2048 x 1080 pixels at 60 fps
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Audio Sample Rates: Audio samples per edit unit are specified based on frame rate and audio sampling frequency (48 kHz or 96 kHz), ensuring precise synchronization between video frames and audio data.
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Conformance and Compatibility: The standard outlines conformance notations, defining requirements ("shall"), recommendations ("should"), and optional elements ("may") for implementers. It maintains alignment with other parts of the SMPTE ISO 26428 suite, specifically SMPTE 428-1 (image characteristics) and 428-2 (audio characteristics).
Applications
ISO 26428-11:2011 is essential for digital cinema professionals including content producers, post-production houses, cinema distributors, and projection system manufacturers who require:
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Accurate Artistic Rendering: Support for varying frame rates preserves directors' and cinematographers' artistic choices, especially when films are produced in non-standard frame rates aligned with regional broadcast standards (e.g., 25 fps in PAL regions).
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Interoperable D-Cinema Delivery: Enables interoperability across digital cinema delivery platforms, ensuring that theaters worldwide can project content at supported frame rates while maintaining audio-video integrity.
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Flexible Production Pipelines: Facilitates production workflows involving a variety of equipment and regional standards, allowing seamless integration of films shot at alternate frame rates without compromising quality or synchronization.
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Enhanced Viewing Experience: Higher frame rates such as 50 and 60 fps accommodate smoother motion portrayal especially for action sequences and stereoscopic 3D, improving viewer immersion.
Related Standards
ISO 26428-11:2011 is part of a comprehensive suite of digital cinema standards ensuring consistent content distribution and playback. Relevant related standards include:
- ISO 26428-1:2008 – Digital cinema distribution master, Part 1: Image characteristics (primary frame rates and image parameters).
- ISO 26428-2:2008 – Digital cinema distribution master, Part 2: Audio characteristics.
- ISO 26428-9:2009 – Digital cinema distribution master, Part 9: Image pixel structure and serial digital interface signal formatting.
- ISO 26429-4:2008 – Digital cinema packaging, Part 4: MXF JPEG 2000 application.
- ISO 26429-10:2009 – Digital cinema packaging, Part 10: Stereoscopic picture track file.
This standard interfaces with broader SMPTE standards like SMPTE 428-11 and supports evolving technologies in digital cinema production, distribution, and exhibition.
Keywords: ISO 26428-11, digital cinema, D-cinema, additional frame rates, 25 fps, 30 fps, 50 fps, 60 fps, SMPTE 428-11, digital cinema distribution master, AFR levels, digital cinema audio, edit unit, digital cinema standards.
