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Retransmission control

We have reached the end of another year filled with all-too-familiar stories. The U.S. transition to DTV is beginning to feel a bit like “Ground Hog Day.” We could just make a digital copy of this year's editorial calendar and toggle a few bits during 2003 to reflect the glacial pace of the terrestrial transition.

This column is supposed to tell a story about “broadband for broadcasters.” Broadband vs. broadcasters would put a more interesting spin on the subject.

Figure 1. A key authentication and exchange subsystem and a digital encryption/decryption subsystem would typically be required for a device to be compliant with digital transmission content protection, as applicable to the IEEE 1394 interface.

In October we looked at conditional access technology for broadcasters. The bottom line is that they don't have a CA system, or an infrastructure to deploy one and collect fees for premium programming. Broadcasting has been built on a foundation of “unconditional access.” But that foundation is crumbling because of the digital transition and the threat from the Internet.

According to the media moguls, the ability to make and share digital copies of content is turning consumers into a bunch of thieves and pirates.

This leads one to ask how broadcasters could possibly have survived without retransmission control for all of these decades? And it raises another question: What is stopping consumers from redistributing analog television content via the Internet today?

The answer to the first question is simple: There are laws to prevent the unauthorized redistribution of copyrighted content. There are two possible answers to the second question. First, consumers have no compelling reasons to redistribute TV content via the Internet. Second, they lack the bandwidth needed.

One might assume that existing laws requiring a broadcaster's consent for retransmission adequately protect broadcasters. One might also assume that professional pirates are not going to be intimidated by a few bits in an ATSC transport stream that any hacker can easily get around.

Content owners seem more concerned about controlling their customers than the pirates. They are concerned that the quality of digital — especially HDTV — is too good; that perfect copies will quickly show up around the world, spread via the Internet. For this reason, they will not make their best stuff available to digital broadcasters unless it is protected from redistribution via the Internet.

So broadcasters created the broadcast flag. Unfortunately, the October story propagated a bit of misinformation about the flag: “On the surface, the broadcast flag appears innocuous enough. Just a few bits that tell a receiver whether a program can be copied unlimited times, once or never.”

A friendly e-mail from the NAB Office of Science and Technology noted an error in this description:

“The so-called broadcast flag effectively has only two states, assertion that redistribution to the Internet should not occur (the descriptor present) and no assertion.…It says NOTHING about copy once. See ATSC Amendment 3 to A/65A.”

Equipped with a broadband connection, I hit the Internet in search of an understanding of the full scope of the conflict.

The “hole” story

First stop, the ATSC. Amendment 3 to A/65 tells us that the purpose of the Redistribution Control (RC) descriptor is to convey a certain type of redistribution information held by the program rights holder for audio, video or data events, and to signal “technological control of consumer redistribution.”

As outlined in the NAB e-mail, the rc_descriptor is either present or not. If present, there is an expectation for control of redistribution. Rather than defining this control, however, the amendment simply states: “It is out of the scope of this standard to assert how any receiving device reacts when the rc_descriptor is present.”

The burden of implementing the broadcast flag does not fall upon the broadcasters or the content owners. By enabling one bit for each program in the ATSC transport stream, broadcasters have done their part to control redistribution. The same is true for the content owners; they just put a provision in their contracts requiring that the rc_descriptor be turned on.

The burden falls to the product manufacturers, and the networks that transport the bits. The consumer will be forced to pay for the hardware, software and license fees needed to protect content when the rc_descriptor is present. And the consumer will be subject to the inevitable frustrations of not being able to use products they purchase legally when the technology does not work properly.

As an example, a cable system recently turned on a content control bit (similar to the rc_descriptor), and consumers with new D-VHS recorders suddenly found that they could not record any programs from the cable system.

The scope of the problem grows larger and larger as the number of digital devices and connections grows.

The consumer electronics industry and broadcasters appear to be in sync when it comes to protecting the “fair use” rights of consumers. But there are still disagreements about where fair use rights end, as related to making legal copies of media and moving media files across networks that extend outside the home. For example, you might be allowed to play a DVD you own on a DVD player in your vacation home, but you probably could not use an Internet connection to move a legal copy of a movie or broadcast program to a PVR in your vacation home.

Meanwhile, the content moguls are seeking perfect control — the ability to be compensated for every use of their content. But even if redistribution control is possible with new digital devices, there is still no way to plug the analog hole. A consumer could still point a camcorder at a TV display and use legacy equipment to encode it and distribute it via the Internet. The real question, however, is: Why would they bother?

Encouraging “legal” behavior

Is it really necessary to protect content producers from the consumers who are sending them billions of dollars each year? And how much is all of this protection going to add to the cost of future digital media products?

The movie industry does not appear to be suffering. Box office receipts are at an all-time high, and DVDs are turning into a digital gold mine.

Implementation of the retransmission control descriptor could burden every digital media appliance and networking device with added hardware costs and license fees. A major contender is the digital transmission content protection (DTCP) system. This system requires each device to implement a key authentication and exchange subsystem and a digital encryption/decryption subsystem to protect all content moving over the digital link (see Figure 1).

High-definition displays are now beginning to incorporate the digital video interconnect with HDCP, another form of encryption, to protect the bits that flow between a set-top box or video recording device and a display. If HDCP becomes a required form of protection for HD content, several million first-generation HDTV monitors may not be able to display HD content. The HD source would be limited to 480p resolution for output on analog component connections.

Now you may understand why broadband for broadcasters is not in the picture. And why DTTV is not in the picture for many confused consumers.

Craig Birkmaier is a technology consultant at Pcube Labs, and hosts and moderates the Open DTV Forum.

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