Electronic Cinema: The Need for Interoperability
by Michael Karagosian
© 1999 MKPE Consulting All Rights Reserved Worldwide
Published June 1999 in Systems Contractor News
While much talk has been given to recent advances in video projector technology and the potential for server-based playback of media in cinemas, not much has been said concerning the nature of the products that will make up the systems in Electronic Cinema. The introduction of server-based technology to cinema systems implies networked distribution of media signals and control and monitoring communication. New technologies will be developed to meet the security and maintenance requirements of electronic cinema. It is important at this early stage to push for an interoperable architecture that will encourage competition and not create monopolies around particular product areas. Without competition, much of the potential for electronic cinema will be lost.
Let's look at the system architecture itself to better understand where a closed architecture should be avoided. Many of the areas discussed are areas where SMPTE standards activity could benefit the industry.
In the server-based system architecture, a central storage bank becomes the electronic repository for all media shown in the cinema. Both video and audio signals emanate from the server to the screen projectors and sound systems.
Figure 1. Block Diagram of Media Server
From the audio perspective, the server concept replaces the need for the complicated cinema processor. A much simpler speaker processor will replace it, supplying gain control, active crossovers and equalization. The recent trend in cinemas to place amplifiers behind screens will lead to the placement of the speaker processor behind the screen as well.
Out of physical necessity, film storage methods such as platters have been located near the projector. Sound equipment has also been located near the projector since the sound storage medium is usually the film itself. Obviously, in the electronic cinema, the need for physical proximity of source and projector or speaker processor will no longer be the case. Though early retrofit systems will likely have their components physically close, the model of choice should be server-based. The transmission of media data to the projector and speaker processor should use the same technologies both in the physically-close model and in the server-based model.
Figure 2. Screen System Block Diagram
Video compression needs special consideration for quality, acceptable storage requirements and security. Certainly, electronic cinema should be perceptibly different from consumer formats. Standards regarding aspect ratios might be considered.
Multichannel audio is not new to the industry, as the film industry has a rich history of multichannel audio formats. Existing digital multichannel formats are limited in channel count by their storage mechanism, that being either data bits on film or on CDROM. A new storage method should support at least 12 channels of audio to bring flexibility to future productions. Compression is expected but should be light to ensure quality.
Special effects have been introduced on occasion to the viewing audience. New digital storage methods should provide space for control data that would trigger future special effects.
Sophisticated automation and remote monitoring have not always been a consideration in the design of current products available in the cinema world. With a networked, all electronic format, networked automation and monitoring will allow sophisticated remote on-screen consoles to be developed for entire complexes. The same technology can provide a means for remotely located maintenance personnel to monitor the health of the systems. The result should be improved consistency in quality in the cinema.
Security of the video signal is of prime importance to the system. The system itself has to be intrinsically secure without the need for any support from the theatre owner. For the video signal, that means an encoded signal that requires a key to decode. Keyed security is not new to the industry as similar security is performed today with the DTS audio CDROMs distributed around the world. It seems prudent that the same keyed encoding method used to store the video signal also be used to transmit the signal to the projector and speaker processor, providing a fully locked signal path.
Figure 3. Block Diagram Showing Transports, Decoders,
and Keys Interoperability
The system architecture and the system requirements identify the areas where technologies have to be developed, or at least standardized, to have interoperable products. These are:
- Video compression and secure decoding
- Audio compression and secure decoding
- Transport for encoded video from server or playback unit to the projector
- Transport for encoded audio from server or playback unit to the speaker processor
From the control and monitoring aspect, these areas should also be addressed:
- Video projector control and monitoring
- Audio speaker processor control and monitoring
- Server control and monitoring
To prevent splintering of the industry over the choice of these technologies, a "committee of experts", usually meaning a standards body, should stand behind the choices. The technologies chosen may be proprietary, but should be made uniformly available to those manufacturers who choose to license them. Ownership of a technology should not become the means for building a monopoly, or a near monopoly, at the product level. Monopolies stifle innovation, and innovation is what keeps this industry alive.
I have had considerable experience with the standardizing of control methods through my experience in the AESSC. My suggestion for control methods is that standard protocols not be considered. Instead, a combination of software technology and transport technology should be standardized. IP transports have proven their utility in the network world, and are supported by a large body of knowledge that can be readily tapped. The technology provided through Microsoft's ActiveX Controls or Sun Computer's JavaBeans should be relied upon so that innovative, custom displays can be easily created by third-parties both for use in the cinema and for use by remote maintenance technicians.
For the implementation of electronic cinema, there are several areas of technology that should be standardized by an organization such as SMPTE. The results of standardized technology will be interoperable and innovative products that will promote competition and provide users with quality choices.