Yesterday, the SMPTE released a series of revisions to the SMPTE Interoperable Master Format (IMF) standards documents (SMPTE ST 2067) to ensure compliant implementation, bring additional features to the IMF system, address conflicts among various provisions, and improve consistency for end users. The revisions address results from IMF Plugfests, as well as feedback from implementers and users working with IMF standards to enable real-world content versioning, packaging, and delivery.
IMF provides a single, interchangeable master file format and structure for the distribution of content between businesses around the world. The revisions announced yesterday apply to SMPTE ST 2067-2 IMF Core Constraints, SMPTE ST 2067-3 IMF Composition Playlist, SMPTE ST 2067-5 IMF Essence Component, and SMPTE 2067-21 IMF Application #2E.
Specific changes to SMPTE ST 2067-2 IMF Core Constraints include added support for IMSC 1.1 timed text, added support for Forced Narrative timed text sequences, and definition of asset identification for Sidecar Composition Map assets. Audio Virtual Tracks have been made optional.
Additional CPL Markers have been included in SMPTE ST 2067-3 IMF Composition Playlist, and a provision in SMPTE ST 2067-5 IMF Essence Component was altered to eliminate a conflict with a provision in ST 2067-201. The ST 2067-21 IMF Application #2E has been revised so that it incorporates the provisions of both ST 2067-20 and ST 2067-21, consolidating provisions from SD to UHD formats for IMF mastering with JPEG 2000.
For end users, this revision to Application #2E is most significant, as it eliminates some of the variability between various essence files, in turn increasing the likelihood that files will work “out of the box.” Because SMPTE made no major changes affecting backward compatibility, existing files should continue to work as expected.
As part of the Society’s initiative to support the industry through and beyond the COVID-19 crisis, SMPTE has made several of its IMF standards available for free download, among other standards documents.