While the Internet has yet to become an ideal medium for distributing premium content, the good news is there’s much more to come from technology advances that have already gone a long way toward enabling secure, efficient delivery of high-quality entertainment to devices of all descriptions.
In fact, these advances promise not only much better performance for unmanaged over-the- top (OTT) content; they will also streamline efforts of service providers that are developing hybrid managed services where IP-based content is a critical component of multi-device service strategies.
One key development along these lines is progress toward a unifying standard for adaptive streaming under the auspices of the International Organization for Standards’ Moving Picture Experts Group (ISO-MPEG). The MPEG Dynamic Adaptive Streaming over HTTP (DASH) working group has proposed a solution that does away with maintaining separate manifest formats for the two most prominent streaming platforms on the Web – Apple’s HTTP Live Streaming (HLS) and Microsoft’s Smooth Streaming.
At the same time, Hollywood studios through their electronic sell-through initiatives, including most notably the Digital Entertainment Content Ecosystem’s (DECE) UltraViolet platform, have created mechanisms essential to a more interoperable and consumer-friendly online content marketplace. Along with equipping UltraViolet to provide in-the-cloud support for single user accounts, DECE has specified a common file format for all UltraViolet content together with rigorous certification procedures to enable the supply of content protection from multiple vendors.
The Benefits of Adaptive Rate Streaming
When it comes to delivering long-form video over the Internet and bandwidth-constrained access links, one of the great tools invented to compensate for bandwidth fluctuations and other disruptions is Adaptive Rate Streaming (ARS). ARS dynamically adjusts bit rates to changing network and device conditions so that content is delivered at the highest level of quality that can be sustained at any given time without dropping frames or interrupting the flow for buffering.
Thus, for example, for streams targeted to HD sets, ARS bit rates might support an optimum resolution of 1080p when conditions allow and then drop down to rates suited to lower resolutions such as 780p when conditions would cause the stream to stop and buffer if the higher bit rates were maintained. Different ranges of bit rates can be set for different ranges of resolution, depending on the screen sizes of targeted devices.
ARS is a device-driven “stateless” technology, which means the ARS system must match the ARS mode that is supported by the client software running on any given device. At the initiation of a video streaming session by any user on any device, the device is presented live manifest files that define each of the available bit rate profiles for the chosen content. The device signals which profile should be streamed based on what the available access data rate is on the network and how much processing power is available on the device to handle the video stream.
To accommodate fluctuations in network bandwidth and other conditions, the ARS servers rely on feedback from the device to continually update the bit rate profile throughout the session. Every few seconds another file segment or “chunk” is sent to the device at the requested bit rate.
The two most commonly used ARS modes, Apple’s HLS and Microsoft’s Smooth Streaming, have much in common. They both rely on H.264 encoding to set the bit rates. And they employ HTTP (HyperText Transfer Protocol), the streaming protocol that supports the sequence of client request and server response transactions that are the foundation to communications on the World Wide Web. But they are incompatible because they employ different transport container formats.
HLS uses the MPEG Transport Stream format while Smooth Streaming uses the Fragmented MP4 file format for its chunks. The differences in container file sizes impose different time sequences on the client-server communications of the respective ARS systems.
The DASH Initiative
If these differences could be resolved, the fact that H.264 has emerged as the dominant codec by far in IP video communications would make it possible to fashion an ARS standard that would easily fit into the existing video streaming ecosystem. This is precisely what the MPEG DASH working group is attempting to do.
In October 2010, the DASH platform achieved Committee Draft status with expectations that it will reach Final Draft International Standard status by July 2011. The core of the draft is closely aligned with the mobile industry’s 3GPP Adaptive HTTP Streaming (AHS) specification.
AHS, adopted by 3GPP in March 2010, relies on the ISO Base Media File Format ISO/IEC 14496-12, the basis for the MP4 container, to create a uniform approach to streaming video and audio content to mobile devices. DASH has expanded on AHS (now commonly referred to as 3GP-DASH) to create the means by which clients can order ARS segments from servers that use either MP4 encapsulation or MPEG-TS.
This functionality is accomplished through a server-to-client communications mode that delivers a structured collection of data in a format known as the Media Presentation Description to define various segments within the stream, each of which is associated with a uniquely referenced HTTP URL. Altogether these segments describe how a DASH client can use the information to establish a streaming service for the user.
Thus, DASH has been structured to not only provide the means by which the DASH client can order chunks in MP4 or MPEG-TS mode, but to open standardized means of accessing many other functionalities as well. These include support for live streaming as well as progressive download of on-demand content; fast initial startup and seeking; enhanced trick modes and random access capabilities; dual streams for stereoscopic 3D presentations; Multi-view Video Coding used in Blu-ray 3D displays, and dynamic implementation of diverse protection schemes. The platform is designed to work with any HTTP 1.1-compliant server and to support distribution through regular Web infrastructures such as HTTP-based CDNs. This is critical to scaling a common streaming mode to a mass consumer base through use of the embedded base of server farms associated with CDNs worldwide.
Support for DASH
The fact that Microsoft and Apple have joined a global lineup of major firms to bring coherence to adaptive streaming represents a major step forward in the evolution of IP-based distribution of premium content. In a recent blog, Christian Kaiser, vice president of engineering at Netflix, extolled the progress on DASH, saying it has addressed most of the major points required to facilitate a standardized approach to video streaming in conjunction with use of the video playback facility in HTML5, the new multi-media optimized version of the Web’s HyperText Markup Language.
“Since HTML5 includes a facility to embed video playback (the <video> tag), it seems like a natural next step for us to use it for streaming video playback within our HTML5-based user interfaces,” Kaiser said. “However, as of today, there is no accepted standard for advanced streaming through the <video> tag.”
He said such a standard should define acceptable A/V container formats; audio and video codecs; the streaming protocol to be used (such as HTTP); how the streaming protocol adapts to available bandwidth; a way of conveying information about available streams and other parameters to the streaming player module, and a way of exposing these functionalities into HTML5. Netflix has resolved all but the last of these requirements with its own proprietary technology, he noted.
If Netflix could replace its proprietary solution with a standardized ARS platform that met all these conditions, the company and “any other video streaming service could deliver to a standard browser as a pure HTML5 web application, both on computers and in CE devices with embedded browsers,” Kaiser said. “Consumers would benefit by having a growing number of continually evolving choices available on their devices, just like how the web works today for other types of services.”
In Kaiser’s view, DASH provides a solution that would meet all his criteria, with the exception of the last one pertaining to having a way of tying the standard into the HTML5 <video> tag. He said Netflix is engaging with the community to help achieve this integration. Kaiser noted that Netflix intends by early next year to publish a limited subset of the MPEG DASH standard, which will refine the requirements for premium on-demand streaming services. Critically, he noted, the Netflix profile “will take advantage of hooks included in the DASH standard to integrate the DRM technologies that we need to fulfill our contractual obligations to the content providers, thus covering the sixth item [conveying parameters to the player] on our list.”
The fact that DASH creates a way to readily communicate to devices what the specific DRM parameters are for a given piece of content overcomes a major barrier to scaling availability of premium content cost effectively. Today, a content supplier who wants to provide a greater level of security than is supported on any given ARS platform must take specific steps to secure each targeted device with the appropriate DRM client. DASH will allow any DASH-compliant DRM to be implemented automatically with no need for intervention by the content supplier.
Challenges to DASH
Needless to say, DASH will not immediately eliminate all the chaos surrounding competing ARS platform with their variations in codecs, DRMs and streaming profiles. Notably, it remains to be seen how Adobe will adjust to the new standard, although the firm’s move away from sole reliance on proprietary compression with its embrace of H.264 on Flash 9 and 10 and its implementation of an HTTP-based ARS system on Flash 10.1 points to a more open approach in the future. Most recently Adobe indicated it is preparing to provide means by which broadcasters who publish video in Flash can deliver that video to HLS-equipped devices, including the iPhone and iPad.
Another development moving against the tide of ARS standardization is Google’s WebM initiative, which aims to provide what it says is an open-source alternative to H.264 without relying on HTTP streaming. Google says its Chrome browser will abandon support for H.264 in favor of WebM, although its YouTube videos continue to use H.264-based Flash as well as older VP6 compression in videos based on pre-9.0 versions of Flash. Suppliers of the Firefox and Opera browsers, which have never used H.264, will go to WebM in their latest versions.
WebM uses the VP8 video compression format developed as a successor to VP6 by On2, which Google acquired in 2010. It uses the Vorbis codec for audio, which comes out of an open-source project headed by the Xiph.Org Foundation. The transport container used by WebM is based on the Matroska Multimedia Container, the product of another open-source initiative.
Rather than relying on the chunk-based process used by ARS, WebM employs proprietary techniques in conjunction with variable bit rate encoding to effect rate fluctuations within a continuous stream. Describing WebM as an “untried technology,” Ben Schwartz, CTO of Innovation Consulting, in a white paper produced by Harmonic and Verimatrix, questioned the practicality of the variable bit rate (VBR) alternative to ARS. “It is much harder to benefit from caching with this approach, and head-end scalability might become an area of concern,” Schwartz said.
At this nascent stage, it is hard to say how much traction WebM will gain or even whether it will prove to be as royalty-free as Google would like. In February, MPEG-LA, which manages the H.264 patent pool, issued a call for patents related to VP8 in what appeared to be preparations for an assessment as to what royalties might be due from users of VP8.
Microsoft, while not opposed to WebM, indicated it wants to know how Google will provide protection to WebM users against patent claims before it whole-heartedly embraces WebM in its Internet Explorer browser. While Internet Explorer 9 users who install third-party WebM video support on their Windows operating systems will be able to play WebM video in IE9, IE9 will otherwise play HTML5 video in the H.264 format, because H.264 “is a high-quality and widely used video format that serves the Web very well today,” said Dean Hachamovitch, Microsoft’s corporate vice president for IE.
Writing in a blog posted in February, Hachamovitch cited Microsoft’s experiences with previous efforts to offer its Window Media Video (WMV) compression technology (later standardized by the SCTE as VC-1) on an open-source basis as a strong reason to doubt that patent infringement claims won’t be made against VP8. “Asserting openness is not a legal defense,” Hachamovitch said. “The risk question is a legitimate business concern,” he continued. “There are hundreds if not thousands of patents worldwide that read on video formats and codec technologies. Our experience with trying to release WMV for free and open use, and the subsequent claims against Microsoft, support this history as do the cases against JPEG, GIF, and other formats.”
Microsoft offered to work with Google to resolve the risk issues. “Microsoft is willing to commit that we will never assert any patents on VP8 if Google will make a commitment to indemnify us and all other developers and customers who use VP8 in the future,” Hachamovitch said. “We would only ask that we be able to use those patent rights if we are sued first by somebody else. If Google would prefer a patent pool approach, then we would also agree to join a patent pool for VP8 on reasonable licensing terms so long as Google joins the pool and is able to include all other major providers of playback software and devices.”
Clearly, with wide support and the blessing of Apple and Microsoft, DASH is by far the best hope for creating an ARS template that content distributors worldwide can rely on to ease the pain of providing premium content with acceptable quality of experience across all networks and a broader range of device types. As DASH comes into commercial use, distributors employing advanced protection mechanisms will be able to upgrade their distribution networks for content delivered to any DASH compatible client.
UltraViolet
Another major force for simplifying IP-based content distribution is UltraViolet, the electronic sell-through platform developed by the Digital Entertainment Content Ecosystem (DECE). The consortium of more than 60 companies is driven by major studios, including Sony Pictures Entertainment, Fox, Lionsgate, NBC Universal, Paramount, and Warner Bros. Many of the powerhouses in media distribution, retailing and technology are also involved with DECE, including Adobe, Best Buy, BT, CableLabs, Cisco, Comcast, Cox Communications, HP, Huawei, IBM, Intel, LG Electronics, Liberty Global, Microsoft, Motorola, Netflix, Neustar, Nokia, Panasonic, Philips, Samsung Electronics, Thomson and Toshiba.
Once the UltraViolet ecosystem is operational, which is scheduled to happen this summer, consumers will be able to create a cloud-based account with digital rights locker via one of many UltraViolet service providers or through the UltraViolet website. They will then be able to access and manage all of their UltraViolet entertainment for use on all their devices, regardless of where the content was purchased.
The UltraViolet Digital Rights Locker serves as the hub for this new marketplace. The authentication service and account management system allows consumers to access content from multiple registered devices over multiple service outlets operating on broadband and mobile networks. DECE will provide an open API (Application Programming Interface) that allows any Web-enabled storefront, service or device to integrate access to the digital rights locker into its own consumer offering.
To the extent UltraViolet eventually scales to mass usage, the platform will drive uniform approaches to file formatting and DRM that could become a force for standard practices across the entire IP video ecosystem. The UltraViolet Common File Format can be licensed by any participating company to create a consumer offering that will play on any service or device built to DECE specifications. Content providers will be able to encode and encrypt one file type in portable, standard and high definition modes with assurance their files can be accessed by consumers from home storage or the cloud from any registered device.
By mandating a common encryption format and setting rigorous requirements for certifying DRMs for use in UltraViolet, DECE is taking the guesswork out of DRM selection by content distributors and greatly simplifying their ability to accommodate multiple DRMs. Because the file format establishes where in the file sequence various DRM functionalities must be implemented, the cloud-based and local storage systems are able to implement whatever UltraViolet-certified DRM is appropriate to a given piece of content.
DECE has gone a step further toward streamlining content protection by embracing Marlin as one of the approved DRM systems – one of the true multi-vendor DRM systems in the marketplace today, and also security standard at the heart of the Open IPTV Forum’s open standards efforts. Marlin, originated by Panasonic, Philips, Samsung Electronics, Sony and Intertrust Technologies, establishes sophisticated, uniform processes for managing rights on devices in a way that can be integrated into a flexible commercial revenue security offering.
Marlin, which is gaining traction in many parts of the world, was recently selected by the U.K. YouView initiative (previously known as Project Canvas) as the common protection model for all content distributed through the group’s new YouView video store. YouView will aggregate and deliver catchup and on-demand content from the BBC, Channel Five, ITV, Channel 4, BT, Arqiva and TalkTalk to set-top box devices from a range of CE vendors.
Critically, there’s a direct tie-in between Marlin and DASH insofar as DASH has drawn heavily on the work of the Open IPTV Forum. Thus the fact that Marlin is intrinsically compatible with DASH serves as another step forward in the content industry’s efforts to overcome encumbrances to efficient operations resulting from DRM incompatibilities.
By Steve Christian, Screen Plays
