What Is the Interoperable Master Format? A Closer Look at IMF

By in Video Editing

Content demand for online platforms and digital viewing devices is ever-increasing, leaving teams to face complicated delivery processes, increased costs, and long production timelines. The Interoperable Master Format (IMF) addresses these challenges by offering a standard package that simplifies the creation of multiple tailored versions of the same content for different audiences.

IMF has existed for several years, and more editing tools are making it easier to export footage to meet IMF delivery specs. Yet, there’s still considerable confusion about it within the industry. This guide will provide a high-level overview of how IMF works and the unique industry challenges that make it a necessity.

Defining the Interoperable Master Format

IMF is a file-based framework held up by the Society of Motion Picture and Television Engineers (SMPTE) as standard 2067-2. It’s designed to simplify the file exchange process by creating a single master file for distribution. That means distribution of content between businesses, however, not for delivery directly to the consumer.

IMF is actually an evolution of the Digital Cinema Package (DCP), which has been the standard for distributing theatrical content since 2012. Over the last few years, IMF has been adapted to suit the particular challenges of broadcast and online distribution. Specifically, it’s made it easier to manage and process multiple versions of a film or promo to fit, say, airline edits, special editions, alternate languages, or territorial compliance.

IMF gives teams a solid workflow that helps them stay consistent—even across different countries—as they tackle QC, mastering, and versioning for productions.

How IMF Works

Instead of a single master file that holds a particular version of a program, an IMF package contains all the essence (audio and video) and the metadata (including subtitles and captions) associated with a piece of content. These are treated as individual assets.

When combined in various ways, these assets create different versions of the content in a composition, such as the Chinese theatrical cut or an airline edit. The Composition Playlist (CPL) defines the playback timeline for the composition. Prime Focus Technologies uses a great analogy: if the assets are the ingredients, then the CPL is the recipe.

An IMF can contain unlimited CPLs. Each represents a unique combination of the files contained in the package, such as different cuts of a program. The CPL isn’t designed to contain media itself—instead, it references external track files that contain the actual essence. This structure makes it possible to manage multiple compositions and process them without duplicating common essence files.

Since IMF can help create many different distribution formats from the same composition, it needs a set of technical instructions to keep it all in order. Enter the Output Profile List (OPL). The OPL specifies the processing and transcoding instructions for the CPL, incorporating additional modifications like sizing, audio, and channel mixing to produce the finished product.

Why IMF Makes a Difference

IMF simplifies distribution workflows and lowers both costs and time to market. After all, it’s easier to manage and keep track of assets when there aren’t hundreds of standalone versions of a title.

For Netflix—one of the principal architects of IMF—a key benefit is reducing several of its most frustrating content tracking issues, namely those related to “versionitis” or the complexities of supplying multiple versions to global markets.

For example, Netflix explained that it frequently runs into problems when trying to sync dubbed audio and subtitles. To preserve the original creative intent, Netflix requests content in its original format, which includes the native aspect ratio and frame rate. Before IMF, Netflix might receive a 24 fps theatrical version of the video for a feature film—only to discover afterward that the dubbed audio and subtitles didn’t match, since they may have been created from the 29.97 fps version or even another version that was recut for international distribution. This is exactly the kind of asset management frustration IMF is meant to address, and ultimately it makes handling acquired content for compliance and outgoing programming for sales a lot more straightforward.

From the facility’s point of view, IMF circumvents the need to put together individual edits and ship them to each market. Rather than shipping a specific media file to Italy, for example, a facility just has to validate the editing list and send that to the territory. There, the appropriate version will be rendered from the master media files.

Not only will the data transfer be significantly less, but this cuts down on the processes involved, the duplication of effort within the team, and the number of files that have to be created due to varying file formats.

There are other benefits to incorporating IMF delivery into a facility’s pipeline. IMF offers improved video quality, since the distributor gets direct access to high-quality IMF masters. It’s also a way to reduce the opportunity for human error: since metadata is kept intact with physical assets, it’s able to be tracked and synced to at all times. IMF also offers a streamlined approach to making incremental changes like new logos and content revisions.

A Look at IMF Going Forward

IMF for broadcast and online was ratified by SMPTE in 2018, and it’s still maturing as a standard.

It went through revisions in June 2020 based on users’ feedback as they came across early teething problems. For example, the revisions address conflicts among various provisions, improve consistency for end users, and introduce additional features to the IMF system.

Bruce Devlin, SMPTE standards vice president, said the revisions “reflect increasing adoption of the standard and learned wisdom through operational practice across the theatrical and broadcast communities.”

Finish and Deliver with Precision

Media Composer’s IMF packaging tools make OTT-destined content a speedy delivery.

Adrian Pennington is a journalist, editor, commentator, and copywriter on film and TV production. Follow him on Twitter: @Pennington1.