IMF: An Open Standard with Open Tools
As Netflix expanded into a global entertainment platform, our supply chain needed an efficient way to vault our masters in the cloud that didn’t require a different version for every territory in which we have our service. A few years ago we discovered the Interoperable Master Format (IMF), a standard created by the Society of Motion Picture and Television Engineers (SMPTE). The IMF framework is based on the Digital Cinema standard of component based elements in a standard container with assets being mapped together via metadata instructions. By using this standard, Netflix is able to hold a single set of core assets and the unique elements needed to make those assets relevant in a local territory. So for a title like Narcos, where the video is largely the same in all territories, we can hold the Primary AV and the specific frames that are different for, say, the Japanese title sequence version. This reduces duplication of assets that are 95% the same and allows us to hold that 95% once and piece it to the 5% differences needed for a specific use case. The format also serves to minimize the risk of multiple versions being introduced into our vault, and allows us to keep better track of our assets, as they stay within one contained package, even when new elements are introduced. This allows us to avoid “versionitis” as outlined in this previous blog. We can leverage one set of master assets and utilize supplemental or additional master assets in IMF to make our localized language versions, as well as any transcoded versions, without needing to store anything more than master materials. Primary AV, supplemental AV, subtitles, non-English audio and other assets needed for global distribution can all live in an “uber” master that can be continually added to as needed rather than recreated. When a “virtual-version” is needed, the instructions simply need to be created, not the whole master. IMF provides maximum flexibility without having to actually create every permutation of a master.
OSS for IMF
Netflix has a history of identifying shared problems within industries and seeking solutions via open source tools. Because many of our content partners have the same issues Netflix has with regard to global versions of their content, we saw IMF as a shared opportunity in the digital supply chain space. In order to support IMF interoperability and share the benefits of the format with the rest of the content community, we have invested in several open source IMF tools. One example of these tools is the IMF Transform Tool which gives users the ability to transcode from IMF to DPP (Digital Production Partnership). Realizing Netflix is only one recipient of assets from content owners, we wanted to create a solution that would allow them to enjoy the benefits of IMF and still create deliverables to existing outlets. Similarly, Netflix understands the EST business is still important to content owners, so we’re adding another open source transform tool that will go from IMF to an iTunes-compatible like package (when using Apple ProRes encoder). This will allow users to take a SMPTE compliant IMF and convert it to a package which can be used for TVOD delivery without incurring significant costs via proprietary tools. A final shared problem is editing those sets of instructions we mentioned earlier. There are many great tools in the marketplace that create IMF packages, and while they are fully featured and offer powerful solutions for creating IMFs, they can be overkill for making quick changes to a CPL (Content Play List). Things like adding metadata markers, EIDR numbers or other changes to the instructions for that IMF can all be done in our newly released OSS IMF CPL Editor. This leaves the fully functioned commercial software/hardware tools open in facilities for IMF creation and not tied up making small changes to metadata.
The IMF Transform uses other open source technologies from Java, ffmpeg, bmxlib and x.264 in the framework. These tools and their source code can be found on GitHub at (https://github.com/DSRCorporation/imf-conversion).
imf-conversion - NF IMF media conversion utility allows to handle flat file creation from a specified CPL within the…github.com
IMF CPL Editor
The IMF CPL Editor is cross platform and can be compiled on Mac, Windows and/or Linux operating systems. The tool will open a composition playlist (CPL) in a timeline and list all assets. The essence files will be supported in .mxf wrapped .wav, .ttml or .imsc files. The user can add, edit and delete audio, subtitle and metadata assets from the timeline. The edits can be saved back to the existing CPL or saved as a new CPL modifying the Packing List (PKL) and Asset Map as well. The source code and compiled tool will be open source and available at (https://github.com/IMFTool):
We hope others will branch these open source efforts and make even more functions available to the growing community of IMF users. It would be great to see a transform function to other AS-11 formats, XDCAM 50 or other widely used broadcast “play-out” formats. In addition to the base package functionality that currently exists, Netflix will be adding supplemental package support to the IMF CPL Editor in October. We look forward to seeing what developers create. These solutions coupled with the Photon tool Netflix has already released create strong foundations to make having an efficient and comprehensive library in IMF an achievable goal for content owners seeking to exploit their assets in the global entertainment market.
— by Chris Fetner and Brian Kenworthy
Originally published at techblog.netflix.com on September 15, 2016.