This comes a year after the Virtual Reality Industry Forum was founded at CES 2017 and is designed to generate momentum at a time when interest in VR is flagging among many content makers.

The VR industry is determined to avoid the fate that afflicted 3D technology around five years ago and the broad scope and depth of the guidelines suggests that objective at least will be achieved. In any case, VR has already gained significant traction within the gaming sector and also includes several core technological components, such as object based audio and 360-degree video, that are associated with Ultra HD and likely to be quite widely deployed in any case.

Furthermore, the same technologies also underpin the closely related field of Augmented Reality (AR), which at present is more popular with many users. VR is about simulating reality to enable experiences, space walking for example, that the user may never experience directly. AR on the other hand is about applying many of the same technologies, including computer generated imagery (CGI), to enhance actual content rather than simulated reality.

AR also does not necessarily need assistance form additional components. A major barrier against mainstream adoption of VR, which has even deterred some gamers from adopting it, is the plethora of gear needed to deliver the full experience. This includes a head-mounted display with high-resolution OLED (organic light-emitting diode) screen, handheld controllers for signaling the user’s intentions and usually two wall-mounted sensors for tracking the user’s movement. Furthermore, as was the case for 3D, available VR content so far has been underwhelming for many mainstream users.

While the VR guidelines cannot address either of these deficiencies directly, the guidelines can provide the foundation for future delivery of compelling content to evolving VR equipment by encouraging development of a standard infrastructure. "As virtual and augmented reality continue to evolve, the VRIF Guidelines serve two main purposes: first, to support end-to-end interoperability across the virtual reality ecosystem, from production to consumption, and second, to ensure a high-quality user experience," said Rob Koenen, President of the Virtual Reality Industry Forum. "As the industry moves towards standardized VR solutions, we are also cooperating closely with other industry organizations including MPEG, 3GPP, DVB, VR Society and ITU to facilitate technology integration for VRIF member companies and other related partners."

VRIF published the guidelines for IBC in September 2017 to make them publically available for review ahead of the final version. The guidelines cover five key areas. First is the role of HDR (High Dynamic Range) in content presentation, highlighting what works and what does not. Secondly come recommendations for stitching video content into the production domain. Third are master format adaptations to permit distribution over bandwidth-constrained links. Fourthly is a focus on passing the desired viewport to the secure trust zone. The fifth major topic is content encryption and watermarking on viewport dependent media profile. The viewport is simply the 2D window on which a 3D field of view is projected.

Much Work Remains

The parts of the guidelines to provoke most interest perhaps focus on issues with some unique aspects for VR. In the case of 360-degree video the guidelines recommend ensuring through careful design and testing that the viewing experience does not cause disorientation, although at this stage without specific recommendation. For audio, the guidelines point out that in a VR world it cannot be assumed that the action all takes place in front of the viewer. Therefore, it suggests that audio cues be created in all directions, including behind and below ear level, which is not usually done or indeed possible with speaker systems at present. It is therefore confined to headsets. Clearly object based audio could help separate sounds clearly between different cue points.

The guidelines also summarize additional security challenges posed by VR content. Naturally the fundamental objectives are the same, being to protect the rights of the copyright holders and distributors, while ensuring privacy of users. But there may be new levels of rights, such as entitlements for given resolutions, control over output and navigation.

More significantly, the guidelines suggest that the MovieLabs Specification for Enhanced Content Protection (ECP), which describe a widely accepted set of high-level requirements for securing content, will need to be extended for VR. The guidelines stipulate four areas where such extensions will be needed, threats to content, requirements for DRM systems, platform specifications and end-to-end system specifications.

Among threats to content not embraced by the ECP are new forms of return path data generated by VR systems, including the Head Mounted Display tracking data and controller input. The VR Forum describes such data as a form of “digital exhaust”, which must be protected from interception and properly anonymized to avoid its revealing information about the user.

VR also brings some significant challenges under the fourth security heading of end-top-end specifications, for example forensic watermarking. The key point here is that VR audio-visual content is created and rendered differently from traditional content so that current watermarking algorithms will not work. For example, the Field of View in the Head Mounted display may only occupy a small percentage of the full 360° frame, which violates the assumption that a full frame is displayed. This means the watermark may not be recoverable. Furthermore, distortion caused by the various VR display transformations, such as equirectangular projection or spherical lens warping, may also make the watermark difficult to recover. While these problems are solvable they have yet to be addressed and need to be given that watermarking is being mandated not just by MovieLabs but increasingly by holders of rights to other premium content, especially live sports.

What is clear from inspection of these guidelines is that the VR movement is addressing issues that are relevant for the video service industry as a whole as it embraces immersive services.