The interactive PDNE

Cable set-top boxes, such as the Scientific-Atlanta HDTV-capable unit pictured above, are not required to include off-air ATSC tuners, but they may need to honor the Broadcast Flag if the cable system carries protected broadcast content. Cable boxes already include robust content protection and will likely use many of the same content protection technologies as ATSC receivers and STBs..

In a recent report, “5 Technologies to Watch,” the Consumer Electronics Association prognosticates about the future of the “intelligent home.” A future where in-home networks, computing and home entertainment devices are interconnected to control the home environment and share digital media content. When it comes to prognostications, this author has established a credible track record. For example, I first wrote about the personal video recorder (PVR) concept in 1992, laying out the reasons that this technology would change the way we consume entertainment and information. Based on the ever-increasing storage capacities for hard disk drives, I predicted that the PVR would become a viable and successful product when the cost of a sufficiently large hard disk reached $100. That happened last year.

TiVo now has more than one million subscribers. DirecTV and Dish have deployed more than two million set-top boxes (STBs) with PVR capabilities. And cable is scrambling to catch up. Scientific Atlanta announced that it has shipped 177,000 Explorer 8000 cable STBs in the last fiscal quarter, for a cumulative total of 563,000 units since its introduction last year.

Seeds of discontent

In the December 2002 Download column, we examined the debate surrounding the development of a content management system for DTV broadcasts. At the time, the Broadcast Protection Discussion Group (BPDG) was trying to reach consensus on a method to implement the redistribution control descriptor, already standardized by the ATSC. Any product encountering a broadcast bitstream marked for protection by this descriptor would be required to implement an approved technology to prevent the content from being redistributed via the Internet. The BPDG did not reach consensus, leaving the thorny issues for the FCC to decide.

A year later, the FCC has ordered that beginning on July 1, 2005, DTV tuners and downstream devices will be required to look for the “Broadcast Flag” and to implement a content management technology that will prevent Internet redistribution of DTV content. In this ruling, the FCC tried to address the concerns of all interested parties. In so doing, it has added another incomprehensible layer of complexity to future DTV products. From here, it looks like this action will further delay the broadcast DTV transition, rather than accelerate it.

Irrational behavior?

Sadly, the entire rationale behind the Broadcast Flag is based upon the prognostications of an industry with a history of resisting any technological change that is viewed as having the potential to be disruptive, and then using the technology to increase the profits of the industry.

That industry is loosely called “Hollywood.” The effort to raise the Broadcast Flag has been headed by the Motion Picture Association of America (MPAA), with help from the big conglomerates that now control the creation and distribution of more than 85 percent of the television content consumed in the United States — content that is now the largest economic export of the United States. It was the MPAA that went all the way to the Supreme Court in an attempt to block the sale of the VCR.

The MPAA successfully lobbied for the Broadcast Flag by predicting the “Napsterization of DTV.” The FCC order says that content owners and broadcasters equally assert that DTV broadcast content must be protected and that, in the absence of some protection mechanism, high-value content will be withheld from broadcast television and migrate to pay services.

The reality is that high-value content has been migrating to pay services for two decades. A highly profitable niche market for HDTV products and content already exists, and there is a strong correlation between the homes that historically have subscribed to premium TV services and those that are buying HD-capable displays.

Those opposed to the concept that free-to-air broadcasts must be protected claim that the threat is overblown. They point out that it's easy to convert today's analog broadcasts into files that can be shared, yet this has not resulted in widespread redistribution of broadcast TV content. They note also that broadband speeds are far too slow to support HD file sharing, and that there is little evidence that most people are interested in sharing TV programs in a manner akin to music.

The FCC sided with those who predict a future problem by saying that although technological constraints may inhibit the redistribution of HDTV today, the potential for piracy will increase as technology advances.

Death of the integrated TV?

Let's look at some facts. While the majority of HD-capable displays sold today do include an NTSC/analog cable-ready tuner, they do not include a DTV tuner. This means the largest group of installed DTV tuners today is in the form of HD STBs for DirecTV's satellite service.

The recent FCC action to bless the agreement between the cable and CE industries for plug-and-play compatibility puts the CE industry in competition with the vendors of proprietary digital cable STBs. Thus, the most likely path for manufacturers will be to separate the display from the STB. In that way, they can offer consumers their choice of cable or DBS subscription services, or an STB optimized only for off-air reception of NTSC and ATSC signals. This means it will still be possible for consumers to buy a video monitor, and then add an external STB supplied by a retailer, cable or DBS service that won't receive OTA broadcasts!

The FCC order mandating DTV tuners includes the following footnote (page 12): “The discussion herein pertains only to broadcast television receivers as defined in Section 15.(3)(w), i.e., those intended for reception of service on the television channels authorized for service under Part 73 of the rules. See 47 C.F.R. 15(3)(w). The requirements adopted in this action do not apply [emphasis added] to devices such as cable and satellite service receivers that are not designed to receive broadcast TV signals over-the-air.” This provision allows the CE industry to build STBs that do not implement any of the DTV tuner and Broadcast Flag mandates.

So what does all of this really mean? In essence, there is no way to protect digital broadcasts reliably unless they are encrypted, and there is tight control of the devices that can decrypt and view digital broadcasts. This would instantly obsolete all of the DTV receivers sold to date. It's not feasible to eliminate analog outputs without making most HD displays obsolete.

The FCC's interim solution is to place the burden of content protection in three areas: DTV tuners, with the networks potentially being used to move these bits around your “home” network and the viewing devices. The exact boundaries of permitted use are still being negotiated. The FCC's Further Notice of Proposed Rulemaking seeks comment on the usefulness of defining a personal digital network environment (PDNE), within which consumers could freely redistribute digital broadcast television content.

The Broadcast Flag order does not mandate any specific content protection technology. Instead, it calls for the creation of a process by which competing technologies will be approved by the FCC; and a process to withdraw the approval if the technology is widely breached after deployment. The FCC is expected to bless two technologies already approved for use in digital-cable-ready TVs.

For security, digital transmission content protection (DTCP) will be used to encrypt protected streams as they travel across user-accessible buses. DTCP is fully implemented for IEEE 1394 (Firewire), with a specification being developed to extend this to Ethernet-based IP networks. For uncompressed digital links between a device and a display, high-bandwidth digital content protection (HDCP) will be used to encrypt the baseband digital signal as it travels across a protected DVI connection. DTV tuners with unprotected DVI outputs must down-res HD content to no more than 330,000 samples per frame (roughly 480p resolution).

Downstream devices such as a PC with a DTV tuner board also are affected. Tuner boards with unprotected DVI outputs are required to down-res HD content to no more than 330,000 samples per frame (roughly 480p resolution). If a PC is to display HD content, the system must be protected so users cannot copy or distribute the compressed bitstreams.

In order to share a bitstream between devices, the devices must agree if the target device is authorized to decrypt and view the content. If the device is physically connected outside of the PDNE, it can access devices in the PDNE via the Internet.

Digital format wars?

The FCC decision to allow for the approval of competing solutions may be the worst aspect of the Broadcast Flag order. This approach creates the real possibility that products may not interoperate, even if the intended use is authorized. In order for a product to play all available content from any protected device, it would need to support all of the approved protection technologies. Philips strongly objected to FCC selection of DTCP, pushing their alternative of watermarking the content. Thus, a DVD recorder using DTCP could produce a disc that would not play on a Philips DVD player that used a different protection method.

The prospect of manufacturers using different protection technologies could effectively lock consumers into the products of a particular manufacturer (or group of manufacturers). All this could give new meaning to the term “Format Wars.”

Craig Birkmaier is a technology consultant at Pcube Labs, and he hosts and moderates the OpenDTV forum.

Web links

CEA Report “5 Technologies to Watch”
December 2002 Broadcast Engineering, “Retransmission control”
Digital Transmission Licensing Authority (DTCP for IEEE 1394 and IP networks)
Digital Content Protection, LLC (HDCP for DVI)

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