[April 5, 2009 email update from Howard Lukk to IMF Contributors reflector]

Greetings from the IMF Tech Chair,

I wanted to take some time a give everyone a general sense of the direction and status of the IMF Technical Committee work. The first thing you may have noticed is that the name has changed from DVP (Digital Video Package) to IMF or Interoperable Master Format. There was much debate about this at both the technical and management level of this project. One of the main reasons for the change was that both Package and Video are not exactly true to the “Master” set of files that we were discussing. One obvious reason is that some of these files may not be “video” at all. They could be still images, audio subtitles or any other combination of such content. The second term “Package” can also be incorrect when describing some of these files as well. Generally a “package” is something that is bundled up and shipped. One of the main differences between the Digital Cinema Package (DCP) and the IMF is that the IMF may or may not be shipped. For example, one could conceive that the IMF would reside on a large storage device and immediately be transcoded to the delivery formats required. In that case, it does not ship at all and therefore would not be a “package”. As the discussion progressed it was clear that we were talking about an “interoperable” “master” set of files. IMSF just did not hold anyone’s attention, and so Interoperable Master Format took hold and a consensus was gained around that. We have now begun collecting dollars from everyone at the committee meetings that uses the old name “DVP”. I believe that I am the largest contributor to that fund.

Most of the work at the technical committee has been around establishing the framework of the IMF Specification document. To that end, we have created the general requirements and scope of the work. We have broken some of the work into the sections of Essence, Metadata, Track Files, Composition Playlists and Packages. We are now concentrating on the Composition Playlist, as the area to define more of the detailed requirements. This is truly where everything is tied together, so we are looking at some concepts that are an expansion on the current DCP Composition Playlist. To that end, we are looking into the concepts of another layer to the CPL with more granularity allowing for simple transitions in the image and audio. We are also discussing the way to convey the Image metadata such as pan and scan information, color conversion and simple color correction similar to the CDL concept. As for the audio portion, we have started a sub group of audio experts to examine the requirements specifically for audio such as sampling rate, down-mixing and dynamic range control.

We have also narrowed down for the moment the image formats to work on. We have chosen a limited set of “swim lanes” so that our work would not get out of control with trying to provide for everyone’s favorite format at this time. This lets us concentrate on the framework instead of nuances between image formats, so for the moment, we are concentrating on the 1920×1080 23.98/24p and 1280×720 59.94/60p formats. This is not to say that we have ruled out any other format, we are just concentrating on these to get through the first process in creating the IMF framework. Along with this, we have a group within the tech committee looking into accommodating both an uncompressed version and mezzanine level compressed version within the IMF.

We are now beginning version 0.4 of the IMF Specification document. We have the first chapter reviewed and have started reviewing chapter two. We are looking forward to sharing the work in progress with you, and will do so as soon as we have enough of the framework for discussion completed (so as to avoid any confusion that may arise). We will keep you posted via email, but we are hoping to have a completed first pass review document ready around the first part of the summer. There is a lot of work to be done to get to this milestone. I am hopeful, however, that we can reach this deadline as I believe that we have now come to a consensus around the core issues of the IMF and can now get some details added to the document.
I hope you have found this helpful. Please understand that this is always subject to change and is meant to be a base for discussion not any final resolution. We do encourage feedback from everyone and take each comment seriously.

Best Regards,
Howard Lukk
Chairman, IMF Tech Committee