VOD Delivery of Client-Watermarked Content. Deterring piracy of high-value video content via individualized watermarking

Transcription

1 VOD Delivery of Client-Watermarked Content Deterring piracy of high-value video content via individualized watermarking August 2013

2 Executive Summary This paper describes an architecture that serves as a deterrent to piracy of highvalue video content delivered on-demand to devices using adaptive HTTP streaming. The system works by uniquely altering, or watermarking, video delivered to each viewer in such a way that it is visually imperceptible, persistent though video processing (such as re-encoding or re-capturing via a camera pointing at a screen), and detectable through special forensic techniques. The alterations in the video store information uniquely identify the user to which the video was served, so that if the video is pirated and distributed, it is possible to identify the pirating customer. The system is designed to be highly scalable and to work with both caching content delivery networks (CDNs) or direct distribution, delivering video using just-in-time (JIT) packaging technology that can provide multiple benefits for video-on-demand (VOD) applications, including a flexible, future-proof design, significant storage cost savings, and delivery of content in multiple HTTP delivery formats. The Emergence of Multiscreen Video Two market trends are changing the way video is delivered to consumers. First, there is a growing proliferation of consumer devices tablets, smartphones, smart TVs and gaming consoles that can display high-quality H.264 video delivered over internet protocol (IP). Second, new protocols for adaptive HTTP streaming of video have enabled an optimal user experience over dynamic network connections, supported by an inexpensive CDN infrastructure that can work over both managed and unmanaged networks. The ecosystem to support the on-demand delivery of high-value content includes, among many other components, the following key functional elements below: 1) Transcoders/Video Processors to prepare source video at multiple bitrates and resolutions for delivery over adaptive HTTP streaming protocols; 2) Just-in-Time Packagers (or Segmenters) that encapsulate and deliver the video to clients using specific HTTP streaming delivery protocols, such as Apple s HTTP Live Streaming (HLS), Microsoft s Smooth Streaming (MSS), Adobe s HTTP Dynamic Streaming (HDS), and the emerging MPEG Dynamic Adaptive Streaming over HTTP (DASH); 3) Scramblers that encrypt the video, often integrated into the Packager; 4) Key Management Servers (KMS) for client device authentication, entitlement and encryption key creation/distribution to clients; 5) Content Delivery Networks (CDNs) that allow large numbers of clients to view video without overwhelming the core network by caching video closer to the edge of the network RGB Networks Page 2

3 In this architecture, video content is created as high-quality source files that must be processed to utilize the video and audio codecs, resolutions and bitrates used to deliver video using HTTP streaming. Because there are multiple formats in use today, it is desirable to store the processed assets just once, in a mezzanine format, and not in every final delivery format. A Just-in-Time (JIT) Packager is the component that can deliver a user request for a specific segment in a specific delivery format by extracting the video and audio data from the mezzanine file and converting it to the requested format. For high-value content, the video segments are encrypted by the packager as well, working together with a Key Server that creates encryption keys and ensures their secure delivery to authenticated clients for decryption. In a multiscreen world, there is an increased potential for piracy with illegal content being distributed across multiple networks and screens threatening revenues and requiring additional security. Even encrypted content can still be captured by recording it from a video display using a video camera, and so encryption may not be a sufficient hurdle to stop piracy. Forensic video watermarking technology, described in the next section, can be used to identify the source of these and other leaks of protected content. Overview of Forensic Video Watermarking The use of watermarking for digital video content directly addresses key challenges in the fight to maintain and enhance the revenue potential in content distribution systems. Digital watermarking is a technology that seeks to securely, robustly and imperceptibly embed identifying information within copies of media content. These aspects are worth understanding in more detail: 2013 RGB Networks Page 3

4 Imperceptible marking is required to preserve the quality of the viewer experience and avoid any implication that the watermarked delivery channel reduces the integrity of the original material. Imperceptible marking draws a specific contrast to some visible overlay techniques used to help trace illegitimate channel rebroadcasting. Security is necessary to preserve the integrity of the inserted information, and especially to prevent any modification of embedded watermark information as copies are distributed. Robustness ensures that the watermark remains readable through any reasonable manipulation or transformation of the media. The most robust watermarks will survive multiple transitions from digital to analog format and be unaffected by filtering and distortion. Forensic watermarking offers pay-tv operators new revenue opportunities by enabling access to content, such as premium on-demand content for the early release window (ERW) the timing of which runs in parallel with the theatrical release and presents a subscriber retention and growth opportunity. Several U.S. studios are committed to ERW and require digital watermarking (together with encryption and selectable output control) to ensure the security of this valuable asset. Reliability, security and quality of the digital watermark are required to get support from studios and content owners, but they are only one side of the equitation to enable watermarking. The other requirements stem from the ability to implement content variations that are unique to every subscriber. With the segmentation of client devices and multiple playback environments, the modification in the client device after the content has been received is not always practical. The other approach, that involves modifying content in the headend, delivers uniquely prepared streams to each recipient. This approach requires the modifications to be applied to the encoded content stream, so they can be efficiently applied with minimum overhead during streaming of individual sessions. This is enabled with a pre-processing step that determines modifications that are applied during the delivery of the content. The figure below illustrates the entire process from pre-processing to embedding, and eventually the forensic tracking stage RGB Networks Page 4

5 Pre-processing The content is pre-processed once at ingest time to analyze the media, while considering factors such as compression requirements, invisibility, robustness and security variations. Locations for individual modifications are identified and formatted such that they are directly applicable to the compressed bit stream. Embedding Payload embedding is performed on every uniquely delivered copy of the content and is driven by the analysis output from the pre-processing step. A unique payload identifier is embedded by performing predetermined modifications that do not require decoding of media content itself. In the case of pre-processed segments, the embedded process is reduced to the individual selection of the segments that uniquely identify the client device RGB Networks Page 5

6 Just-In-Time Packaging (JITP) When delivering VOD HTTP streams, two options are possible: either the assets are stored in an HTTP-ready format, so that clients can make HTTP requests for video segments directly from a plain HTTP server; or, assets can be stored in a canonical or mezzanine format which is then converted to HTTP segments as the client makes requests for them just-in-time. The first option is more disk storage intensive, while the second is more computationally intensive. In a typical JITP use case, file assets are transcoded into a mezzanine format which uses H.264/AAC for the video/audio codecs and a pre-selected container format. MPEG-2 TS container format is a natural choice for the mezzanine files, since it can contain much of the signaling present in the original signals in an industry-standard way. This is particularly useful when the video mezzanine files are captured from live streams for ondemand catch-up TV or network digital video recorder (ndvr) functionality. Clients that request a stream from the JIT Packager first receive a client-manifest describing the available profiles (bitrates, resolutions, etc). The JIT Packager will create the manifest when it is requested the first time; subsequent requests are served from a cached copy. Clients subsequently request specific segments from the Packager which extracts the requested segments from the mezzanine files and delivers them to the clients. Thus, each client request is served from the JIT Packager the more subscribers in a deployment, the more JITP capacity is needed RGB Networks Page 6

7 Why Use JITP? There are a number of reasons why JITP may be a better alternative to pre-positioning assets in all final delivery formats. Storage Cost Savings When multiple HTTP streaming formats are used, every asset must be stored in multiple formats, with associated storage costs. This is especially true for ndvr where legal requirements in some regions mandate that separate copies are stored for each customer. Format Future-proofing The HTTP streaming protocols in use today are still evolving; using JITP of mezzanineformat assets eliminates the need to re-package VOD libraries when these formats change. Changes in formats can be addressed via software updates of the JIT Packager, which can then also manage a heterogeneous ecosystem of different format versions (e.g. various flavors of HLS). This is a huge boon to operators who must otherwise decide on a specific version of a format and thus potentially miss features in new format versions or not serve subscribers who haven t updated their video players. Single Workflow Using JITP for VOD with a caching CDN can automatically lead to an efficient distribution of contents in the CDN that is, the caching of short tail (or commonly viewed) assets in the CDN and the use of JITP for un-cached long tail (rarely viewed) assets. This ensures that new assets automatically migrate into the CDN without requiring a separate offline packaging step in the workflow, as well as a separate, offline determination of which assets are short tail and which are long tail. Graduated Investment New VOD service offering using storage rather than JITP would require all assets to be stored in all formats up front, leading to large initial capital expenditure. With JITP, operators can add VOD capacity as the number of subscribers grows with capital expenses that match subscriber growth and revenue. URL Obfuscation JITP offers the opportunity to obfuscate ads or other sections of video, so that all segments in HTTP requests have the same appearance. Without this feature, automated systems could potentially be employed to extract and remove ads from the main video, leading to reduced returns for operators. Unicast Relationship Because the JIT Packager has a unicast session with the client, it can be used to encrypt VOD sessions uniquely for each client. Moreover, other unicast services, such as targeted ad insertion, can be integrated into the Packager. Note that when segments are encrypted per user, they cannot be cached in the CDN RGB Networks Page 7

8 Cacheable, Scalable, Individualized Watermarking of Content As we describe in the next section, JITP can be combined with watermarking techniques to create client-specific watermarks that can serve as an effective deterrent to piracy. JITP with Watermarking JITP can be combined with watermarking methods described above as follows. Mezzanine file content is watermarked in two distinct ways, denoted 0 or 1. That is, the asset contains segments with watermark bits set to all true in one version, say 1, and all false in the second 0 version. When a client requests an asset, the client identity is detected at the JIT Packager. The client identity may be its IP address, a cookie or other header in the HTTP session, or a token in the HTTP request. This client ID is then encoded as a binary sequence of bits using segments from the 0 and 1 version of the asset, as shown in the figure below RGB Networks Page 8

9 Fingerprinting Fingerprinting is a process by which content can be identified. A fingerprint is a collection of features or characteristics of a video stream that can be used to automatically identify a specific piece of content, e.g. a specific movie. Fingerprinting plays a role in the deterrence of piracy by creating an automatic process for detecting piracy. The process works as follows: the figure below shows high-value, copyrighted content that is fingerprinted before distribution. During distribution, the content is watermarked uniquely for each client. Automatic scraping of content-sharing networks (e.g. YouTube or peer-to-peer file sharing networks) reads content and uses the fingerprints to identify copyrighted material. Content that is identified as copyrighted and illegally distributed is then checked for watermarks, which can then point to the last legal recipient client device of this specific copy that, by implication, was involved in its pirated distribution. Verimatrix StreamMark Applied by the RGB TransAct Packager The patent pending StreamMark technology has been specifically developed by Verimatrix to support a highly efficient, server-side embedding process to uniquely mark compressed and possibly encrypted content during delivery. The particular focus is on minimal overhead of the number and size of modifications to support mass delivery of uniquely marked content in the latest video consumption models, such as over-the-top (OTT) delivery to standard consumer electronics devices including games consoles, Bluray players, connected TVs, PCs and mobile devices, as well as pre-dvd release content on pay-tv networks. These distribution networks need to support a variety of client 2013 RGB Networks Page 9

10 devices and integration in the headend, and Verimatrix StreamMark accommodates these requirements as it does not require any control or modification on the client side. For other distribution networks that offer more device control, client side watermark integrations such as offered by Verimatrix VideoMark remain an important alternative. The embedding process is architected to have extremely low overhead to the point where it can be easily added as a component of stream-based media delivery environments with negligible performance impact. It enables the embedding of a robust, secure and imperceptible transaction or customer identifier in compressed and even encrypted content before distribution to standard decoders and media players in set-top boxes, PCs and mobile devices. All downstream copies of compressed or re-recorded media will contain the unique payload identifier, which can be extracted by systematic, machine aided comparison with the original content, even after severe distortion or degradation. Extraction of the embedded watermark is performed through the Verimatrix Reveal Service. Suspect files to be analyzed are submitted to Verimatrix for extraction of the embedded information along with the original unmarked file as reference. The RGB TransAct Packager is an advanced, scalable multi-feature packager that supports JITP and its associated advantages. When combined with Verimatrix s StreamMark watermarking system, and with additional feature development from RGB, it can provide the following functionality: JITP can work with HLS, HDS, MSS, and DASH and since the watermarking is carried in the video payload, the end-to-end system works with all of these protocols. The individual 0 and 1 watermarked segments can be cached, leading to a highly scalable solution. The system can be protected against mixing attacks in which segments from multiple different client ID watermarked streams are mixed together. This is done by distributing the information in a sparse and redundant way within the watermarking intervals. It is worth noting that the watermarking could be done just-in-time as well, because it is a low computational complexity operation whose associated storage requires a small fraction of the storage space compared to the complete asset. This would lead to a significant reduction in storage, since in this case, separate 0 and 1 versions of the mezzanine do not need to be stored. One version of the mezzanine with the addition of only the areas of the video that are marked with 1 watermarks is sufficient. In a further optimization, it is possible to add watermarks to encrypted content (even without knowing the encryption key), since entire encryption blocks can be replaced during the marking process RGB Networks Page 10

11 Robustness Against Attacks A combined solution of the RGB TransAct Packager and the Verimatrix StreamMark watermarking system provides robustness to various attacks: StreamMark watermarking survives camcording of screens and reencoding of video. URL obfuscation 1 in the TransAct Packager hides the embedding locations and variations, spoiling analysis of protocol with the aim to gather information about the embedding process. Verimatrix s SME codes further distribute information throughout the stream, so that attacks that aim to analyze, mix and obfuscate the embedded information can be detected and the original watermark extracted. Conclusion Delivery of high value content, especially content released during the highly monetizable early release window, requires strong anti-piracy measures. Content owners have already accepted the value and efficacy of watermarking in digital distribution of content to theaters, and the natural extension of this system for unicast VOD OTT delivery is inevitable. Verimatrix s StreamMark watermarking technology, combined with RGB s widely-deployed TransAct Packager can provide a robust, flexible, scalable and studiovetted solution that allows service providers to offer high- value content in multiple formats with reduced storage costs and assurance to their content owners that hurdles to piracy are nearly impossible to circumvent. About RGB Networks RGB Networks provides the industry s most scalable solutions for multiscreen IP video delivery and monetization. Built around a highly reliable transcoding platform and unique adaptive streaming products, RGB s flexible, standards-based evia architecture enables operators to deliver premium live and on-demand video services to any device and generate new revenues through adaptive streaming ad insertion. RGB s high-capacity products uniquely offer the density and scalability required to support the growing demand for video delivery to TVs, tablets, PCs and mobile devices with integrated functionality that simplifies operators network architectures and minimizes operational costs. RGB s award-winning products are deployed with over 400 video service providers worldwide, delivering solutions for traditional and OTT video services. For more information, please visit 1 Future functionality RGB Networks Page 11

12 About Verimatrix Verimatrix specializes in securing and enhancing revenue for multi-screen digital TV services around the globe. The award-winning and independently audited Verimatrix Video Content Authority System (VCAS ) and ViewRight solutions offer an innovative approach for cable, satellite, terrestrial and IPTV operators to cost-effectively extend their networks and enable new business models. As the recognized leader in software-based security solutions for premier service providers, Verimatrix has pioneered the 3- Dimensional Security approach that offers flexible layers of protection techniques, including encryption, key management and digital watermarking, to address evolving business needs and revenue threats. Maintaining close relationships with major studios, broadcasters, industry organizations, and its unmatched partner ecosystem enables Verimatrix to provide a unique perspective on digital TV business issues beyond content security as operators seek to deliver compelling new services. Verimatrix is an ISO 9001:2008 certified company. For more information, please visit RGB Networks Page 12