Broadcast flag
A broadcast flag , also broadcast flag written [ bɹɔːdkɑːstˌflæg ] ( "charisma marking") is a form of digital rights management (Engl. Digital Rights Management , abbreviated DRM) for use in television broadcasts.
At the request of the rights holder, the content providers send this digital signal in the data stream of the television program, whereby compatible devices are controlled accordingly. Among other things, the time-shifted and / or repeated playback as well as the copying and further distribution of individual programs should be restricted or completely prevented, e.g. B. by limiting the number of copies or limiting the playability to only certain, approved hardware.
In contrast to specific implementations for digital rights control , the term broadcast flag only refers to the ability to influence the receiving end in a certain way from the sending end, whether and to what extent recordable (i.e. unencrypted and / or analog) image signals from the receiving device to be delivered.
Implementation
The implementation of a broadcast flag always requires two stages:
The first is that a certain character (a flag) must be transmitted from the sender to the receiver, which sets the protection and / or the level of protection at the outputs.
The second stage is that, depending on the set level of protection, the signal outputs of the receiver are switched accordingly or a signal such as a Macrovision interference pulse is transmitted via them.
At the moment there is a lack of uniform standards, how the flag is transmitted or what it consists of, just as there are already several incompatible approaches for rights management on the output side:
- The widespread (digital) broadcast standard DVB does not contain a general definition of a broadcast flag. Only the audio data contain flags on copyright, which originate from the time of the SCMS - "Copy-Prohibited-Bit" - introduced for digital audio tape . The DVB standard is completely open, so conditions cannot be subsequently attached to the reception of the signals broadcast with DVB. Only the DVB-S 2 standard for satellite transmission with higher bandwidth was only created after the first ideas of a broadcast flag at the end of the 1990s, but it also provides for unencrypted transmission between transmitter and receiver.
- Only a draft for digital transmission according to DVB currently being prepared by industrial committees will presumably result in a “closed” (and presumably also generally encrypted) device standard in which the devices must be approved in order to be able to receive signals transmitted with them.
Three different standards compete for the transmission of rights control information on the output side:
- The oldest "safe" signal transmission is HDCP . However, it does not contain any information about the level of protection, protection can only be achieved by switching on the encryption ( full protection , signal must not be recorded, signal is incompatible for devices not equipped with the "protection system") or by switching off the encryption ( no Protection , no counting of the copy generation).
- There is a variant of the analog signal output, which used to be regarded as "unprotected", with the copy protection standard CGMS-A , which is able to count copy generations and thus e.g. B. to allow a one-time recording, of which however no more copies can be made. But analog signal outputs “protected” by CGMS-A are also considered “defenseless” for HDCP, as there are a considerable number of old recording devices that do not support CGMS-A and so this protection is ineffective on such devices. CGMS-A is a further development of Macrovision (which only works with SDTV and only knows the states no protection ( no interference signal) or full protection (image is output with interference signal)).
- With AACS, there is another type of "protected" signal output, which only works on the level of the digital data stream, i.e. only with the compressed image and sound data. AACS is a complete digital rights control system that z. B. also describes the processes when the signal is saved on a removable data carrier.
Due to these variabilities, a mechanism such as that required for the broadcast flag can currently only be implemented using transmitter-specific restrictions on the receiving devices, as is expressed by the Premiere broadcaster via the requirement for a Premiere HD suitable receiver.
Legal regulations
There are efforts (e.g. on the part of the US regulatory authority FCC ) to force manufacturers of ( HDTV ) reception technology to implement this technology, i.e. only to manufacture devices that are compatible with the copy protection signal (at least for certain markets) and then follow the instructions evaluate correctly and limit usage accordingly. Some manufacturers excel by hurried obedience or use “Hollywood” as the reason for missing or limited product functions. In the USA, a corresponding directive was stopped by a court shortly before it came into force in August 2005.
The planned WIPO Broadcasting Treaty should also require legislative provisions to protect transmitter-specific restrictions on the receiver side.
Although the broadcast flag falls more or less under the protection clauses for copy protection systems of the international WIPO agreements, but since z. If, for example, the transmitter data stream is unencrypted at the latest after decryption by the smart card (for pay TV ), the legal protection is not as comprehensive as would be the case with closed rights control systems.
Many pay TV providers , including cable network operators, (officially) only support devices that meet the requirements they have set; In the future, this will increasingly include the evaluation of a broadcast flag . In return, however, some device classes are also supported that were previously "forbidden" in the terms and conditions for fear of further dissemination , e.g. B. hard disk recorder . However, the use of an unauthorized receiving device may violate clauses in the provider's contracts.