The digital cinema technical ecosystem is changing: the first generation of digital projectors is aging while new technologies arrive for display: LED walls and HDR projectors with different levels of imaging performance. Today we use different Digital Cinema Packages (DCP) for Standard Dynamic Range (SDR), Extended Dynamic Range (EDR) and High Dynamic Range (HDR) cinema displays, and we also need different versions for projection and Direct View Displays. It is a problem for versioning and distribution companies as limited timing is available prior to worldwide release.
With UniPix, we propose a unique DCP that can transport all versions within the same SMPTE structured DCP. The HDR/EDR/SDR versions are played from different Composition PlayList (CPL) matching the display capabilities, for both color volume, dynamic range and framerate performance.
What is the problem?
Today movies may have hundreds of different versions, with localized versions of sound, subtitles and technical specifications (sound formats, object audio, HFR…)
DCI provides a framework for HDR DCPs, but as for now it’s a different DCP, one for direct view display, one for HDR projectors. Our proposition is to put all pictures formats into one DCP, using our Hybrid Tone Mapping and Hybrid Framerate Mapping technologies.
Hybrid Tone Mapping
There are different approaches for transporting video signals with different dynamic range (same content):
- Static remapping: a simple transfer function remaps the HDR signal for an SDR display. While being simple, this approach generally compromises the artistic intent, as some decisions should be made on some shots whether a part of the picture should be hidden to allow watching another part, where in HDR both parts are visible.
- Metadata-based remapping: a processing engine is triggered by some information to dynamically affect the colour and brightness rendering of the image. This allows finer control over the picture and artistic intent, at the cost of extra technology (colour processor) to be implemented in the system.
In our context we wanted to have the benefit of the metadata-based remapping with its fine-tuning capabilities (with even more control) while keeping the simplicity of Static Remapping for implementation, especially in legacy projection systems.
We use the concept of CPL (Composition Play List) in the DCP that allows us to intercut different elements. Elements that are not satisfying for the creative team when being automatically converted to a lower dynamic range can be replaced by fine-tuned versions of the same shots for the display technology.
Mastering Process
- In blue: HDR video asset (mxf)
- In yellow: video asset (mxf) graded for EDR display
- In green: video asset (mxf) graded for SDR display
Hybrid Tone Mapping is compatible with different Electro Optical Transfer Functions, including the Perceptual Quantizer.
Distribution
We now have very efficient DCP distribution systems that already manage many versions through CPL management, integrating UniPix system doesn’t disrupt the DCP distribution process.
Presentation
For the presentation of content, the display system loads the CPL corresponding to the Display Performance Profile and enables the matching Tone Mapping Curve. It is managed exact
Hybrid Framerate Mapping
Hybrid Framerate Mapping allows to carry different framerates within the same DCP. It also relies on the CPL (Content Play List) mechanism to load different multiples of a reference framerate. More information coming soon.
What are the benefits?
On the distribution side, cinemas can download the elements associated to the CPL they require for their cinema equipment. This is a practice already in place with latest TMS
Hybrid Tone Mapping and Hybrid Framerate Mapping are simple to implement in traditional mastering workflows and to deploy in cinema display technologies, both legacy and new.
They are designed to be backward compatible with existing cinema technologies, so deployment cost is minimal, with no hardware upgrade nor additional hardware required.