Patent Application
20100100742
Digital watermarks are data embedded into digital content such as digital audio and video that may be readable by computers. Watermarks may be used for various purposes. One type, forensic watermarks, is used to identify the source and/or distribution path (e.g., source of copying) of legitimate content that is copied without authorization. An example of a distribution path is the specific set-top box that played the content prior to copying. These marks should, inter alia, be invisible (or inaudible), be able to resist intentional and unintentional attempts of deletion, and be recoverable with sufficient assurance so that they can be relied upon for incriminating individuals fairly.
Forensic watermarking is an anti-piracy tool that compliment Data Rights Management (DRM) systems DRMs and Conditional Access (CA) systems. Forensic watermarking can be defined as the embedding of a message within the video that identifies the last authorized party. A forensic watermark can be placed in content at various points along its distribution. If content is found outside of an authorized distribution path, the forensic watermark contained in the content can be used to identify the source of the leak.
Today, content distributors and system operators often insert a watermark that identifies the system operator. This practice is often of limited help in identifying pirates. It may be the case that system operators are much more interested in placing a forensic watermark at their head-ends, at interim points along the distribution path, and in the consumer playback device itself. This systematic use of forensic watermarks can, at the very least, identify most of the path(s) to an authorized consumer and eliminate the opportunity for anonymous redistribution. It may also provide a way to monitor the overall integrity of DRM and CA systems. Such monitoring helps raise awareness of when a leak is present so that a system operator can adjust or renew their security system to prevent or stop such leak.
Forensic watermarking has already proven very useful in professional video applications, including for example pre-release movie screeners on DVD. Forensic watermarking has also been specifically designed to enable forensic watermarking in consumer applications.
A forensic watermark solution for consumer markets may work across a broad range of playback devices, including, but not limited to, personal computers, set-top boxes, portable media players and mobile phones. To support such a wide range of playback platforms, the forensic watermark should be robust but also require minimal processing power to insert a message. Also, to stay ahead of pirates, it should be renewable without having to update the deployed consumer playback devices. Additionally, to track the path of distribution, the forensic watermarking system should support multiple insertions of marks and be able to recover such marks without any reference to the original digital video content.
Various advantages exist for some embodiments directed to consumers. For example, a “compute-efficient” watermark inserter can be deployed across the entire field of consumer digital media players, including currently fielded models. The “compute-efficient” watermark inserter may insert a unique identifier, such as device ID and date/time of playback. Another advantage is that the system is renewable and can support a “blind” watermark recovery system that requires no information about the original source content, channel of content distribution, or player. Source based recovery is also available with no change to the playback watermark inserter.
Some forensic watermarking technologies may be used in the consumer market to solve critical content rights problems. One such problem is movie content piracy—particularly as play windows collapse and high definition content comes to consumer markets. However, forensic watermarking may also be useful in testing the integrity of a distribution channel, thereby protecting the revenue stream of the system operator by identifying where their system is allowing unauthorized access to programming. This testing may become particularly important as DRMs become more interoperable and the content distribution path includes two or more DRMs, and where system operators want to expand into new types of services, such as network hosted personal video recorders (Virtual PVRs).
To the content owner, forensic watermarking may provide a definitive link between a pirated copy of their content and the legitimate channel where the copy originated. This technology has proven to be a useful tool for identifying and tracking down large scale and individual pirates.
To the system operator, forensic watermarking may provide a tool to positively link (or disassociate) a pirated copy of content to their distribution system. This aspect means that system operators can identify where security in their system needs to be renewed. Once identified, system operators may be able to better manage their operating costs and reduce revenue losses. It may also mean that they can make a case with the content owner for higher value content, and thus increase the value of programming.
To the consumer, forensic watermarking may act to “keep honest people honest.” In the same way that a consumer will not try to steal clothing from a shop with sensors at the door, that same consumer would not illegally distribute content that had a watermark that could be tied back to them.
Forensic watermarking may supplement some DRM systems. In some applications, forensic watermarking may be used to continue to provide protection once the content leaves the DRM envelope.
Users of such traditional watermarking systems include video distribution systems, such as Video-on-Demand (VOD) and web-based downloads, encrypt content prior to storage on the distribution servers. The Conditional Access (CA) system 180 provides encryption keys to the encryptor 120 at the point of content ingest, and to the CA modules at the content viewing point 160 (generally, this is the smartcard at the set-top-box).
Video forensic watermarking processes require access to unencrypted content 110 to perform analysis and modification of the video. Because of this, a content distribution system using a traditional watermarking system to embed a unique watermark on each downloaded stream has three options. First, store the content unencrypted. This solution has obvious security implications, but also does not address the high-performance goals of a large distribution system. Second, use a partial-encryption scheme. While this is a fairly popular field of discussion, this solution is only marginally better than storing the content unencrypted. Even if it succeeds in encrypting a majority of the data, the distributed content has unencrypted portions that may act as markers for the location of watermarks. Also, this solution may have unaddressed performance issues. Third, store the content encrypted and then decrypt it to perform watermarking.
A distribution system that satisfies the third option is illustrated in
This method has several undesirable characteristics. First, The VOD server may need to be able to decrypt content from every CA vendor. Second, the VOD server may need to support decrypt/encrypt for numerous simultaneous streams. Third, the content may be in the clear briefly on the VOD server. It is generally considered unacceptable for the CA to allow any additional entities (such as the VOD server) to have access to content keys.
What is needed is a secure distribution system capable of: storing content completely encrypted, and uniquely watermarking individual content deliveries without requiring any content decryption (i.e., watermarking the individual content deliveries in the encrypted domain).
Embodiments of the present invention enable real-time watermarking of transport streams without the need to encrypt, decrypt, compress or decompress content streams to apply the watermark. Several of these embodiments will now be described in detail with reference to the accompanying drawings. It should be understood that the embodiments and the accompanying drawings have been described for illustrative purposes and that the present invention is limited only by the claims.
One possible use of the embodiments is apply forensic watermarking to digital content such as movies or audio. Forensic watermarking includes steganographic techniques that allow content providers to manage and track content to specific locations. As one example, forensic watermarking can be useful in monitoring the integrity of Data Rights Management (DRM) systems and Conditional Access (CA) systems described earlier.
The embodiments described in the figures are described using block diagrams and flowcharts, many of the actions and blocks described in both the block diagrams and flow charts may be implemented using functional modules. One skilled in the art will recognize that the modules that may be implemented in software, hardware, programmable hardware such as ASICS, FPGA's, etc, or a combination thereof. Modules may include a digital stream reception hardware that immediately is processed by software, hardware or combinations of software and hardware.
The content processed in these embodiments may include muxed audio/video transport stream(s) with at least the payload of the video PID being encrypted. The content may be encrypted prior to storage on the distribution server and may not need to be decrypted until it reaches the set-top box (STB). These embodiments should: (1) provide security of the content asset while it is in storage and transmission; (2) maintain the integrity of the content key by not releasing it from the CA domain; (3) the distribution server, including the watermark insertion process, may be agnostic to the encryption method used by the CA; (4) the distribution server, including the watermark insertion process, may be agnostic to the content compression (codec) being used; and (5) the embodiments should not require significant computational resources, thereby not artificially limiting simultaneous stream processing.
While this document specifically describes a transport stream implementation, the technique may work equally well for many other packaging formats such as QuickTime, 3GPP and MP4.
As shown in
This solution builds on previous art for video watermarking in the compressed domain. An example of such prior art may be found in U.S. Pat. No. 6,285,774 to Schumann et al. entitled “System and Methodology for Tracing to a Source of Unauthorized Copying of Prerecorded Proprietary Material, Such As Movies.” A new feature here is the introduction of a Watermark Descriptor (WMD) that allows the inserter 420 to perform its duties without looking at the content of the video or the carrier packets.
Within the transport stream, the carrier data (including WMD packets 510) may be stored in a different PID than the video content. The encrypted carrier packets are a 1-for-1 replacement for the encrypted video packets. Each of the video packets 502 and carrier packets 501 should be encrypted in such a way as to not rely on the previous or following data packets. This is normally the case. Since the inserter does not need to look at any of the payload in the video or carrier packets, it is acceptable if the entire payload is encrypted.
Based on the message to be conveyed, the encrypted watermark inserter 420 determines if the encrypted video (representing a ‘0’) or the encrypted carrier (representing a ‘1’) should be in the output video stream. If the encrypted watermark inserter needs to convey a ‘0’ in the stream, the carrier is disregarded and the video is allowed to pass through unaltered. If the encrypted watermark inserter needs to convey a ‘1’ in the stream, then the header from the encrypted video packet (in this case, the 4-byte transport stream header) may be copied over the header of the encrypted carrier packet and the encrypted carrier packet is released while the encrypted video packet is disregarded. (The header from the encrypted video must be copied into the encrypted carrier packet so that the PID and continuity counter are correct for the video stream.)
As shown in the examples illustrated in
The transport stream may be an unencrypted transport stream. However, one skilled in the art may practice embodiments where the transport stream may be encrypted. What is important that some kind of content data be extractable in order to generate processed content packets and/or replacement content packets. The transport stream 610 may be any kind of transport stream that includes content data 715 embedded in content packets 710. Examples of such transport streams 610 include MPEG2 transport streams and MPEG2 program stream. Similarly, the content data 715 may of many types including audio data, video data, database data, instructional data, XML data, etc. The content packets 710 should generally be a packaging format suitable for the specific type of content data 715. For example, when the content data 715 includes video data, the content packets may be in a format such as Quicktime, 3GPP or MPEG4.
The watermark descriptor 830 may include: a bit count 832, an associated packet sequence number 834, an insertion number and a flags field 838. The bit count 832 may be used to identify a location within a watermark message 650. The associated packet sequence number 834 may be used to identify the first of the processed content packets 810 to be used in inserting a message 650 into a watermarked transport stream 660. The insertion number 836 may be used to indicate the number of associated carrier packets (dependent upon the message 650) that may be inserted into the watermarked transport stream 660. The flags field 838 may be configured to indicate whether the second watermark data represents a first value or a second value. The watermark descriptor may be implemented as a packet adaptation field. In some embodiments, the packet adaptation field may be kept in the clear.
Additionally, security data 840 may be included in the processed transport stream 630. This security data may be used in numerous well know ways, such as to verify integrity of the processed transport stream 630. For example, the security data could be a checksum value that is used to verify that all or part of the data in the processed transport stream 630 have not been corrupted or tampered with.
The transport stream receiving module 1210 may be configured to receive the transport stream 610. In some embodiments, the transport stream may be part of a larger transport stream 1110. Content data 715 may be passed along with other relevant data to the associated carrier packets generation module 1220 and the content packet processing module 1230. The content packet processing module 1230 may be configured to generate processed content packets 810. The associated carrier packets generation module 1220 may be configured to generate associated carrier packets 820. The watermark descriptor generation module 1240 may be configured to generate a watermark descriptor 830 for a group of the associated carrier packets 820 using data 1225 determined by the associated carrier packets generation module 1220. Finally, the processed transport stream creation module 1250 combines the associated carrier packets 820, the processed content packets 830 and the watermark descriptor 1310 into a processed transport stream 630.
Each of the processed content packets 810 may include a content packet header. Similarly, each of the associated carrier packets 820 may include a carrier packet header. The replacement module may now insert the watermark indicated by the watermark message 650 by coping each of the content packet headers over each of the carrier packet headers; and then discard the processed content packets 810. This replacing may further include replacing at least part of the carrier packet with filler data. An alternative method to insert the watermark involves exchanging at least part of the processed content packets 810 with at least part of the associated carrier packets 820 according to the watermark message 650.
The transport stream watermarker 640 may be implemented in any number of locations including: in a hardware based content processor; in a software based content process; in an end point device; in a set top box; in an intermediate processor; in a multiplexer; or in a video on demand server.
Up until now, most of the description of embodiments has been around functional modules. However, some embodiments maybe described and/or implemented as a series of actions.
However, one skilled in the art will recognize that there are other equivalent actions that may be taken to create a watermarked transport stream 660 from a processed transport stream 630.
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the present invention. In fact, after reading the above description, it will be apparent to one skilled in the relevant art how to implement the invention in alternative embodiments. Thus, the present invention should not be limited by any of the above described exemplary embodiments. In particular, it should be noted that, for example purposes, the above explanation has focused on the examples of specific embodiments. However, those experienced in the art will realize that multiple other embodiments, including, but not limited to ones disclosed, can be used. For example, throughout this disclosure, watermark message 150 has been described as if it is a message containing a series of two values. One skilled in the art will recognize that the innovations taught here could be expanded to insert a watermark that includes a series of more that two values. To do this, one might include a second or third set of associated carrier packets that include replacement watermark data that represents the third and greater values that may be switched with the processed content packets 810.
In addition, it should be understood that any figures, schematic diagrams, system diagrams, or examples which highlight the functionality and advantages of the present invention, are presented for example purposes only. The architecture of the present invention is sufficiently flexible and configurable, such that it may be utilized in ways other than that shown. For example, the steps listed in any flowchart may be re-ordered or only optionally used in some embodiments.
Further, the purpose of the Abstract of the Disclosure is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The Abstract of the Disclosure is not intended to be limiting as to the scope of the present invention in any way.
Furthermore, it is the applicant's intent that only claims that include the express language “means for” or “step for” be interpreted under 35 U.S.C. 112, paragraph 6. Claims that do not expressly include the phrase “means for” or “step for” are not to be interpreted under 35 U.S.C. 112, paragraph 6.
The present invention can be made from a variety of materials, in a variety of shape and size, for a variety of purpose. The scope of the present invention is limited only by the claims as follows.
The present application claims the benefit of provisional patent application Ser. No. 61/029,401 to Courington et al., filed on Feb. 18, 2008, entitled “Transport Stream Watermarking,” which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61029401 | Feb 2008 | US |
