WebRTC World Feature Article

December 03, 2014

Peer-to-Peer Architecture Could Save Streaming Video


Not a newsflash: the online video market is booming. And escalating demand from consumers for longer and higher-definition content is driving a mass migration of digital fare to content delivery networks (CDNs), to support a good end-user experience. But online video needs a future savior: There’s a clear event horizon where delivery overhead outstrips even CDN capacity.

Ideas for a next-gen approach to digital video distribution are brewing: according to a recent trial, peer-assisted delivery could be the key to optimizing video playout and minimizing infrastructure risks as traffic volumes tax capacity.

The Trouble with CDNs

CDNs were developed as a way of caching copies of popular streaming content closer to the end user, offloading delivery from the content provider's origin infrastructure, resulting in a better use of capacity and possible cost savings for the content provider. But as capacity grows, it will require additional network infrastructure investment to avoid serving up dicey end-user experiences.

“Increasing broadband penetration and faster devices make high-quality viewing experiences possible, but network latency issues and heavy traffic loads can often result in disappointing video streaming performance, with frequent pauses for rebuffering,” said Kurt Michel, CDN giant Akamai’s director of product marketing, in a blog. “Current distribution models are already starting to show their limits.”

And indeed, CDN-based digital distribution has already had a few highly publicized, capacity-related “issues,” like HBO GO’s crashing during the True Detective finale and the Game of Thrones season 4 premieres.  Also, ESPN’s website crashed when 1.4 million simultaneous viewers attempted to watch the U.S.-Germany World Cup match; and ABC’s debut live stream of the Oscars was down for most of the evening.

There are fresh looming issues as well: 4K ultra HD is the next generation in definition for video, four times sharper than 1080p HD. But an UHD file instance is 16 times larger than the same file in HD. While there are compression and encoding technologies like HEVC that lower the impact of packets on networks, there’s no doubt that UHD will increase traffic volume overall.

“The quality expectations of these ever-increasing audiences continue to grow,” Michel added. “Not only is HD quality for online video desired - it is becoming the de-facto standard for all viewing experiences, from HDTV home viewing to anywhere-viewing on mobile devices with ‘better than HD’ quality displays.”

Akamai, which commands the CDN market, is addressing this with new optimization approaches. Its Sola Media Experience portfolio offers a global media workflow and delivery platform that simplifies and optimizes live video streaming. It’s designed to provide the capacity, performance and security for both browser and mobile environments.

Peer-to-Peer Approaches

In addition to optimization for existing network strategies, new ideas are headed to market too. For instance, Streamroot has a WebRTC-based peer-to-peer video streaming solution that it says can address many of the existing limitations in CDNs.

Peer-to-peer streaming eliminates the unicast architecture that until now has been the hallmark of online streaming. Instead of one endpoint pulling down a single unique stream, the P2P approach allows simultaneous users to exchange video segments among themselves rather than each connecting to a server to do so. The more peers involved, the more streams are available, turning traffic into an asset. In theory, this allows broadcasters to scale up, improve quality of streams and handle traffic peaks, all while reducing costs and lightening the burden on saturated network infrastructures.

Decentralizing the exchange of data also significantly improves the quality of service for the end user, as each viewer is able to collect the segment needed from the source that can provide it most quickly. And, peer-assisted delivery can work in tandem with a CDN, offering a fallback solution when traffic levels start to affect the end user quality of experience. Thus, it also reduces economic dependence on CDNs and ensures that viewers can continue watching their content even if the CDN and local server experience temporary outages.

“Traditional unicast protocols based on one-to-one relations between client and server have proven insufficient, with frequent network over-capacity and congestion,” said Streamroot, in a white paper. “Content delivery networks are racing to palliate the situation by multiplying peering points and surrogate servers around the globe. This solution, however, is not scalable ad infinitum, and risks to ultimately fail to provide the reliability sought at an acceptable cost.”

StreamRoot’s specific solution uses a hybrid peer-to-peer video streaming architecture, based on the latest Internet technologies: HTML5, JavaScript, Media Source Extensions and WebRTC. As such, it’s a native solution that requires no plugin, extension or other installation on the part of end users. When a StreamRoot user accesses a Web page, the video content begins loading directly from the server. At the same time, the viewer connects to the StreamRoot tracker and retrieves an intelligently selected list of peers, establishes a direct connection with them and requests video segments. If the peers cannot provide the segments quickly enough, it automatically switches back to the origin/CDN server, guaranteeing at the very least the same quality of service as a CDN-only solution.

Real-World Test Drive

StreamRoot recently partnered with a Russian video-on-demand platform to test its P2P solution on the website’s most popular video during a Friday night peak.

According to the company’s white paper, the trial used 120 minutes of video, in MPEG-DASH, h264/AAC, at 1,000kbps, delivered to a large geographical area spanning six Russian-speaking countries. It had 2,089 users at peak, with a total bandwidth of 2.1Gbps or 1TB per hour.

“In this trial, StreamRoot achieved up to 58 percent peering, with percentages rising at peak use times

(42 to 58 percent streaming at traffic peaks),” the company said. “This data clearly demonstrates the scalability of the P2P model, as the more peers there are, the more data is transferred between them.”

In the middle of the test, the origin server went down entirely for four minutes. But, P2P streaming ensured half of the service during the outage, so that 50 percent of users were entirely unaware that the server had malfunctioned.

“Even the most robust infrastructures are not ready to handle the influx of users that large broadcasters are beginning to experience today,” Streamroot noted. “Another model is needed in addition to traditional unicast distribution. Peer-to-peer adaptive streaming provides a viable, scalable supplement to traditional CDN distribution. With its ability to transform increasing viewer numbers into an asset, peer-assisted streaming based on the latest Internet technologies such as HTML5, Media Source Extensions and WebRTC can offer broadcasters a key competitive advantage, enabling them to reduce costs, improve streams and lighten the burden on saturated network infrastructures.”




Edited by Maurice Nagle




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