Digital cinema has thrived as a license-free format. Anyone can make a DCP without concern for royalties associated with packaging or distribution. The distribution format does not cross any known patents, so that even “royalty-free” use of the distribution format at the grace of a patent holder doesn’t apply. It’s completely open. Likewise, it’s homogenous. Every product in exhibition can read every track file in every Composition without fear of crossing patents.
However, all of this could change in an important way. Dolby would like to create a new type of digital cinema in which proprietary, manufacturer-specific track files can be defined, the use of which will likely require a technology license. This intent, presumably, is targeted for the introduction of its Atmos sound format. To be fair, Dolby may be the most vocal, but it is not alone in this desire. There are other uses for a customizable file format, too, such as motion seats.
The theory of operation for a new “auxiliary track file” is quite simple. The server will recognize the presence of the auxiliary track file. Included in the track file will be instructions for identifying the appropriate auxiliary processor. The server will transfer the track file to the auxiliary processor, and a tightly controlled synchronization signal will keep the auxiliary processor in sync with the media block.
A motion seat processor would follow a similar process. The server doesn’t need to know what’s inside the auxiliary track file. It only needs to ship it off to the correct outboard processor. The outboard processor will not only processes the proprietary file, but it will do so while remaining synchronized with the media block.
To initiate this work, Dolby proposed two new projects this month in SMPTE. One project would standardize the synchronization signal. The other project would standardize the auxiliary track file. Typical of Dolby’s approach to new committee work, no committee discussion preceded these requests. No presentation of the concept was made in ISDCF. No presentation was made in SMPTE to pitch these projects. This significant undertaking was afforded just a few meagerly worded project requests that were dumped on the committee. Accordingly, the explanations offered in this report are not Dolby’s, but an interpretation of Dolby’s actions in an attempt to make sense of them.
The concept of carrying proprietary data in the Composition deserves careful examination by the industry. It is true that proprietary data already exists in distribution, in the form of non-audio data carried as a channel in the audio track file for the purpose of controlling motion seats. It would be fair to say this is a borderline application. No one is enthralled with the use of the audio file for carrying custom non-audio data. However, the introduction of audio channel labeling, recently passed by SMPTE, offers a clean solution to such applications. By making the media block aware of the actual content of each audio channel, a data track won’t end up watermarked or in an auditorium loudspeaker. The argument for allowing the carriage of data in the audio track file is that it is a low cost way to enable the operation of outboard equipment in tight synchronization with the show. If Dolby’s auxiliary processor concept were to be required for operating all outboard devices, such as motion seats, it would surely lead to more costly systems for the exhibitor, if not systems that are more complex and difficult to operate.
Most importantly, the question must be asked as to whether the industry will benefit from custom auxiliary track files. It may be a convenient engineering concept, but it will significantly increase the burden already placed on the distributor. For example, if each 3-D sound format were to require its own auxiliary track file, and, say, two or three such sound systems were to enter the market, each requiring a track file containing up to 128 sound channels, the size of the DCP would grow enormously.
In fact, the concept of the custom auxiliary track file is completely counter to the open track file concept now employed in digital cinema. The core concept behind the structure of the Composition today is to minimize the burden on the distributor. Every track file today can be read and utilized by every server and media block. With the notable exception of motion seats, the distributor is not asked to do something special that benefits only one manufacturer.
There is another argument against customized distributions that is often overlooked. The marketplace embraces new technologies best when they share common distributions. Open standards for closed captions, for instance, were initially booed by those manufacturers that wanted proprietary distributions. But once open distribution was introduced, the exhibition market threw its doors open to closed captions, as competition was allowed to flourish.
The industry is faced with a dilemma. It can either bend over for the manufacturers and go down the path of custom, manufacturer-specific track files, and forever suffer. Or it can tell the manufacturers to clean up their mess and propose standardized track files that support the products that they wish to sell. It’s easy to predict where this will go.