IMF for a Multi-Platform World
Posted: 30 Nov 2011 02:15 AM PST
Among other things, the looming arrival of the Interoperable Master Format (IMF) is illustrating that the digital media industry is now capable of moving "nimbly and quickly" to create technical standards to address and evolve the ways that it packages, moves, and protects precious content in the form of digital assets in a world where the technology used to do all that, and the very industry itself, is fundamentally changing at a startling rate. The term "nimbly and quickly" comes from Annie Chang, Disney's VP of Post-Production Technology who also chairs the SMPTE IMF work group (TC-35PM50).
Six Hollywood Studios through the University of Southern California Entertainment Technology Center (USC ETC) started to develop IMF in 2007, and in early 2011, they created an input document that the SMPTE IMF working group is now using as the basis of the IMF standardization effort. Over time, IMF has developed into an interchangeable, flexible master file format designed to allow content creators to efficiently disseminate a project's single master file to distributors and broadcasters across the globe.
Chang reports that progress has moved quickly enough for the work group to expect to finalize a basic version of the IMF standard in coming months, with draft documents possibly ready by early 2012 that focus on a core framework for IMF, and possibly a few of the potential modular applications that could plug into that framework.
Once that happens, content creators who have prepared for IMF will be in a position to start feeding all their distributors downstream far more effectively than has been the case until now in this world of seemingly unending formats. They will, according to Chang, be able to remove videotape from their production workflow, reduce file storage by eliminating the need for full linear versions of each edit or foreign language version of their content, and yet be able to take advantage of a true file-based workflow, including potentially automated transcoding, and much more.
The rollout will still need to be deliberate as various questions and unanticipated consequences and potential new uses of IMF begin to unfold. But that said, Chang emphasizes that the goal of being able to streamline and improve the head end of the process—creating a single, high quality, ultimate master for all versions is real and viable, and with a little more work and input, will be happening soon enough.
"Today, we have multiple versions, different resolutions, different languages, different frame rates, different kinds of HD versions, standard-definition versions, different aspect ratios—it's an asset management nightmare," she says, explaining why getting IMF right is so important to the industry.
"Everyone creates master files on tape or DPX frames or ProRes or others, and then they have to create mezzanine files in different formats for each distribution channel. IMF is designed to fix the first problem—the issue of too many file formats to use as masters."
Therefore, IMF stands to be a major boon for content creators who repeatedly and endlessly create different language versions of their material.
"For a ProRes QuickTime, you are talking about a full res version of a movie each time you have it in a new language," Chang says. "So 42 languages would be 42 QuickTime files. IMF is a standardized file solution built on existing standards that will allow people to just add the new language or whatever other changes they need to make to the existing master and send it down the chain more efficiently."
Chang emphasizes the word "flexible" in describing IMF, and the word "interoperable" in the name itself because, at its core, IMF allows content distributors to uniformly send everybody anything that is common, while strategically transmitting the differences only to where they need to go. In that sense, IMF is based on the same architectural concept as the Digital Cinema specification—common material wrapped together, combined with a streamlined way to package and distribute supplemental material. Eventually, each delivery will include an Output Profile List (OPL) to allow those transcoding on the other end a seamless way to configure the file as they format and push it into their distribution chain.
Unlike the DCI spec, however, IMF is not built of wholly new parts. Wherever possible, the file package will consist of existing pieces combined together in an MXF-flavored wrapper. This should, Chang hopes, make it easier for businesses across the industry to adapt without huge infrastructure changes in most cases as IMF comes to fruition.
"With IMF, we are using existing standards—a form of MXF (called MXF OP1A/AS-02) to wrap the files, and parts of the Digital Cinema format and other formats that many manufacturers already use," she says. "So, hopefully, there is not much of a learning curve. We hope that most of the big companies involved in the process won't be caught unaware, and will be able to make firmware or software upgrades to their systems in order to support IMF. Hopefully, companies will not have to buy all new equipment in order to use IMF.
"And with the concept of the Output Profile List (OPL), which essentially will be global instructions on output preferences for how to take an IMF file and do something with it relative to your particular distribution platform, companies that are doing transcoding right now will have an opportunity to use that to their advantage to better automate their processes. IMF has all the pieces of an asset management system and can use them all together to create standardized ways to create packages that fit into all sorts of other profiles. It's up to the content owners to take these OPL's and transcode the files. As they do now, they could do it in-house or take it to a facility. But if transcoding facilities get smart and use IMF to its potential, they can take advantage of IMF's capabilities to streamline their processes."
Chang says major technology manufacturers have been extremely supportive of the SMPTE standardization effort. Several, such as Avid, Harmonic, DVS, Amberfin, and others have actively participated and given input on the process, which is important because changes to existing editing, transcoding, and playback hardware and software, and the eventual creation of new tools for those tasks, will eventually need to happen as IMF proliferates. After all, as Chang says, "what good is a standard unless people use it?"
She emphasizes that manufacturer support is crucial for IMF, since it is meant to be a business-to-business tool for managing and distributing content, and not a standard for how consumers will view content. Therefore, outside of the SMPTE standardization effort, there is a plan to have manufacturers across the globe join in so-called "Plugfests" in 2012 to create IMF content out of draft documents, interchange them with each-other, and report on their findings.
As Chang suggests, "it's important to hit IMF from multiple directions since, after all, the first word in the name is 'interoperable.' " As a consequence of all these developments, it's reasonable to assume that IMF will officially be part of the industry's typical workflow chain where content distributors can start sending material to all sorts of platforms in the next year. Some studios and networks are already overhauling their infrastructures and workflow approaches to account for IMF's insertion into the process, and encoding houses and other post-production facilities should also, in most cases, have the information and infrastructure to adapt to the IMF world without any sort of fundamental shift. But the post industry will be somewhat changed by IMF, especially if some facilities or studios decide on processes for automating encoding at the front end of the process that changes their reliance on certain facilities currently doing that kind of work.
However, Chang adds, the broadcast industry specifically will probably have the most significant learning curve in terms of how best to dive into IMF since, unlike studios, which have been discussing their needs and pondering IMF since about 2006, the broadcast industry was only exposed more directly to IMF earlier this year when SMPTE took the process over. IMF was originally designed and intended as a higher bit-rate master (around 150-500MB/s for HD, possibly even lossless, according to Chang), but broadcasters normally use lower bit-rate files (more like 15-50MB/s).
"However, I feel that broadcasters would like to have that flexibility in versioning," Chang says. "But because they need different codecs and lower bit-rates, there is still discussion in SMPTE about what those codecs should be. Broadcasters are only now starting to evaluate what they need out of IMF, but there is still plenty of time for them to get involved."
Of course, as the explosion of mobile devices and web-enabled broadcasting on all sorts of platforms in a relatively short period of time illustrates, viewing platforms will inevitably change over time, and therefore, distribution of data will have to evolve, as well. As to the issue of whether IMF is relatively future-proofed, or merely the start of a continually evolving conversation, Chang is confident the standard can be in place for a long time because of its core framework—the primary focus to date. That framework contains composition playlists, general image data, audio data (unlimited tracks, up to 16 channels each), sub-titling/captioning data, any dynamic metadata needed, and so on.
Modular applications that could plug into that framework need to be further explored, Chang says, but the potential to allow IMF to accommodate new, higher compressed codecs, new or odd resolutions or frame rates, and all sorts of unique data for particular versions is quite high.
"The core framework we created with documents is something we tried to future proof," she says. "The question is the applications that might plug into that core framework (over time). We are trying to make it as flexible as possible so that if, in the future, even if you have some crazy new image codec that goes up to 16k or uses a new audio scheme, it will still plug into the IMF framework. So image, audio, or sub-titling could be constrained, for example, but as long as the sequence can be described by the composition playlist and the essence can be wrapped in the MFX Generic Container, the core framework should hold up for some time to come."
To connect with the SMPTE IMF effort, you can join the SMPTE 35PM Technology Committee, and then sign up as a member of 35PM50. The IMF Format Forum will have the latest news and discussions about the status of the IMF specification.
More information about IMF:
Overview of the IMF presentation at NAB 2011's Post Pit event.
Amberfin's Bruce Devlin SMPTE PDA Now Educational Webcasts, discussing MXF application designs coming out of the IMF Work Group.
By Michael Goldman, SMPTE Newswatch
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