Interoperable Master Format: Difference between revisions

Revision as of 19:54, 24 October 2022

Revision as of 17:15, 3 January 2023

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In IMF, each kind of [[Essence (media)|essence]] (video, audio, subtitles, etc.) is stored in individual media files (“Track Files”) and the instructions for synchronizing these media files are stored in a separate playlist file (“Composition Playlist”).<ref name=":3" /> This component-based approach allows the large media files to be reused across multiple playlists, each representing a different version of the content..<ref>{{Cite web |last=2018-09-16T11:26:00+01:00 |title=IMF: A gateway to component-based workflows |url=https://www.ibc.org/thought-leadership/imf-a-gateway-to-component-based-workflows/3204.article |access-date=2022-05-20 |website=IBC |language=en}}</ref>

The IMF family of standards, ST 2067, is maintained by [[Society of Motion Picture and Television Engineers|SMPTE]].<ref name=":0">{{Cite journal |date=August 2021 |title=OV 2067-0-2021 - SMPTE Overview Document - Interoperable Master Format |url=https://ieeexplore.ieee.org/document/9521128/ |journal=OVOv 2067-0-2021 |pages=1–4 |doi=10.5594/SMPTE.OV2067-0-2021|isbn=978-1-68303-248-9 }}</ref> Its first edition was published in 2013.

IMF is closely related to [[Digital Cinema Package]] (“DCP”), leveraging several of the same standards for packaging and architecture.

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Each Track File contains a specific essence corresponding to a single aspect of the presentation. Track Files are both organized and limited by parameters such as resolution, color space, frame rate, audio sound field, etc. Track Files of disparate parameters may not be mixed in a Composition. Track Files use a constrained version of the MXF OP1a format [[Material Exchange Format]]<ref name=":1" />

The Composition Playlist is an [[XML]] document.<ref>{{Cite journal |date=May 2020 |title=ST 2067-3:2020 - SMPTE Standard - Interoperable Master Format — Composition Playlist |url=https://ieeexplore.ieee.org/document/9097510/ |journal=STSt 2067-3:2020 |pages=1–35 |doi=10.5594/SMPTE.ST2067-3.2020|isbn=978-1-68303-214-4 }}</ref> It assembles the Track Files<ref>{{Cite journal |date=May 2020 |title=ST 2067-5:2020 - SMPTE Standard - Interoperable Master Format — Essence Component |url=https://ieeexplore.ieee.org/document/9099734/ |journal=STSt 2067-5:2020 |pages=1–15 |doi=10.5594/SMPTE.ST2067-5.2020|isbn=978-1-68303-213-7 }}</ref> onto virtual tracks that are synchronized onto a timeline. It also contains metadata associated with that timeline.The combination of a Composition Playlist and the Track Files it references is called a Composition.

Each Composition represents a different version of an audio-visual work. Separating the Composition Playlist from the Track Files allows reuse of Track Files across multiple Compositions, as shown in the reuse example diagram. [[File:IMF Track File Re-use Example.svg|alt=IMF can re-use Track Files to minimize resource usage for versions of audio-viual works.|thumb|IMF Track File Reuse]]

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* plug-ins, which contain optional technology that can be used across multiple applications.

The core constraints are specified in SMPTE ST 2067-2 (Core Constraints).<ref name=":1">{{Cite journal |date=May 2020 |title=ST 2067-2:2020 - SMPTE Standard - Interoperable Master Format — Core Constraints |url=https://ieeexplore.ieee.org/document/9097478/ |journal=STSt 2067-2:2020 |pages=1–43 |doi=10.5594/SMPTE.ST2067-2.2020|isbn=978-1-68303-211-3 }}</ref> An example of an application is Application #2E, which is specified in SMPTE ST 2067-21<ref name=":2">{{Cite journal |date=May 2020 |title=ST 2067-21:2020 - SMPTE Standard - Interoperable Master Format — Application #2E |url=https://ieeexplore.ieee.org/document/9097487/ |journal=STSt 2067-21:2021 |pages=1–34 |doi=10.5594/SMPTE.ST2067-21.2020|isbn=978-1-68303-212-0 }}</ref> and targets studio masters. One of the plugins is the Immersive Audio Bitstream Level 0 Plug-in, which is specified in SMPTE ST 2067-201<ref>{{Cite journalbook |date=January 2021 |title=ST 2067-201:2021 - SMPTE Standard - Immersive Audio Bitstream Level 0 Plug-in |url=https://ieeexplore.ieee.org/document/9343937/ |journal=STSt 2067-201:2021 |pages=1–14 |doi=10.5594/SMPTE.ST2067-201.2021|isbn=978-1-68303-238-0 }}</ref> and adds support for immersive sound.

== Example uses ==

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* Video up to 8192x6224 rasters, lossy and lossless compression, high-dynamic range, wide color gamut and stereoscopic 3D,<ref name=":2" />

* 24-bit 48 kHz channel-based sound, arranged in arbitrary configurations

* Immersive Audio Bitstream (IAB) immersive sound<ref>{{Cite journal |date=June 2019 |title=ST 2098-2:2019 - SMPTE Standard - Immersive Audio Bitstream Specification |url=https://ieeexplore.ieee.org/document/8752533/ |journal=STSt 2098-2:2019 |pages=1–54 |doi=10.5594/SMPTE.ST2098-2.2019|isbn=978-1-68303-178-9 }}</ref>

* Subtitles and captions that conform to the TTML Profiles for Internet Media Subtitles and Captions 1.1 (IMSC 1.1) W3C Recommendation<ref>{{Cite web |title=TTML Profiles for Internet Media Subtitles and Captions 1.1 |url=https://www.w3.org/TR/ttml-imsc1.1/Overview.html |access-date=2022-03-04 |website=www.w3.org}}</ref>