A Stitch in Time: How Stream Stitching Beats the Ad Blockers
Ad blockers are the bane of online video publishers everywhere. Can stream stitching, also known as server-side ad insertion, save the day?
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Premium content owners that monetize their content via video ads face an enormous financial constraint: the effectiveness of ad blocking software.
“Ad blocking software and its impact on video strategies is a topic that we hear in four out of five meetings today,” says Matt Smith (right), chief evangelist for Anvato. “In short, broadcasters, publishers, and programmers are seeing as much as one-third of their video views being compromised as a result of this technology.”
How did we get here, and what can an industry built on pre-roll, interstitial, and post-roll advertising do to combat this massive decline in ad playback?
The answer, according to some, is the concept of “stitching” together the ad and primary content into a single stream. This process is known by several names, but the most common is server-side ad insertion (SSAI).
SSAI allows the playlist, also known as a manifest file, to be delivered to an end user’s device, but with a twist. Rather than the manifest making calls to multiple locations—one for primary content, one or more for ad serving services— the manifest only requests content from a single location. In theory, this makes it difficult for ad blocking technologies to differentiate between primary content and ad content.
There are a few approaches to SSAI, some of which only manipulate the manifest and others that truly stitch the ad directly into the live or on-demand bitstream, but for simplicity, this article won’t differentiate between the two. Instead we will generically call the whole process stream stitching.
According to Smith, “more than $21 billion in ad payload (display and video, to be clear) is being lost in 2015 as a result” of ad blocking. How did we get to this point?
We’ve Come Full Circle
In the early days, before ad serving technologies were required, the ads were “baked in” to the stream. For a live event, an ad might be played into the master control or video mixer via a digital disk recorder (DDR), while an ad destined to play in a piece of on-demand content would be encoded as part of the on-demand content.
These kinds of baked-in ads were referred to as static ads, and often were only available for pre-roll delivery. One of the promises of online video delivery, though, is an ability to customize content to any viewer—a viewer in India might see an ad for a Mumbai sweet shop, while a farmer in Montana might see an ad for the local John Deere dealership—which meant the static ad solution was lacking.
One way to address the issue would be to create hundreds of versions of the same on-demand content, with each version playing in a particular locale. On a global scale, though, that would be unwieldy at best, and the level of granularity for ad targeting would still be lacking.
On the other hand, most streaming companies weren’t equipped with sophisticated ways to serve up thousands of playlists, with each playlist containing the same on-demand primary content with diverse ads based on demographic or geographic information.
Companies serving up dynamic banner ads, though, already had the technology to granularly target content to browsers. A few of these companies saw video ad serving as a large opportunity and began to offer services to premium video content owners.
Because HTML rendering in a web browser works roughly the same way for images and banner ads, with the use of inline content delivery with a “call” or request to a specific URL coded into the HTML pages, these still image ad services had an Achilles’ heel: Anyone who understood the way HTML code worked could simply write a program to block particular calls to particular URLs.
And did they ever. The open-source community created ad blocking software apps, and the crowdsourcing community has continued to improve those over the years. These ad blockers have proven to be very effective against both banner ads and more recent video ads.
Ad serving companies tried to write generic code, which then was interpreted by the ad server as a request for a particular type of ad, but the ad blocking community would find these code strings and block the request.
Then ad serving companies tried obfuscating the ad request, at first by using URL or IP addresses that weren’t part of the standard list of known ad serving companies’ URLs or IP addresses. Those were also blocked effectively. Obfuscation went a step further, with ad requests using multiple redirects before hitting the actual ad server. Even these options have been effectively thwarted by the open-source ad blocking community.
Part of the problem with video ad serving was the need for a seamless end-user experience. No one wants to wait for an ad to load, so most client-side ad insertion (CSAI) required a dualplayer approach: one player for ads and another for primary content.
The dual-player approach had a number of technical challenges, but did allow some ads to be prepopulated to the local user’s computer. But that also presented an opportunity for the ad blocking community to identify the caches and eliminate the ad altogether.
Advances in CSAI continued, including some clever solutions by Adobe that are used as part of its Primetime Player service, yet it seems that a better solution was in order—one that bears a surprising resemblance to the original concept of baking in ads into the stream. Essentially it brings us full circle, but with a twist.
Beyond the Dual Player
That solution, at least as it stands today, is SSAI, the ad stitching technique described earlier.
Brigthcove acquired one of the original stream stitching technology companies, Unicorn Media, a few years ago. Unicorn had labeled its product Once, because it was able to deliver streams to the hundreds of Android and iOS devices from a single source. Brightcove now offers a derivative solution called Lift.
Brightcove’s server- side ad insertion SSAI solution, Lift (formerly called Once, as shown in this diagram), delivers streams to the hundreds of Android and iOS devices from a single source.
Mike Green, vice president of marketing and business development at Brightcove, cites a specific example from Vox Media, a Brigthcove customer, to explain the benefits of Lift and SSAI in general, as opposed to CSAI.
“By implementing Brightcove Lift to stitch ads directly into the video content via server-side ad insertion, Vox Media removed some of the variables and obstacles of client-side ad calls that commonly impact performance for digital publishers,” Green says.
According to Green, Vox faced CSAI challenges prior to implementing Lift. One challenge involved a less-than-seamless end-user experience for mobile devices. “Trying to do client-side ad calls with HLS on Android mobile web was so poor that Vox had actually decided to remove ads there altogether,” Green says. “With Lift, Vox was able to restore monetization on Android and more broadly, on mobile web, the company significantly improved playback consistency and quality, and shortened the time to first frame between ads and video content.”
Anvato’s Smith says that he can’t think of a scenario where his clients would prefer CSAI to SSAI.
“CSAI was good in its day, but introduced characteristics that needed to be improved upon,” Smith says, “including introduction of latency, mismatched quality between program and ad payload, and others.”
Smith says that the ad blocking technologies used against CSAI may have other unintended consequences.
“Client-side ad blockers see many outbound requests that video players make as a call for an ad,” Smith says. “Think of it in military terms as friendly fire. The initial request for playback may be viewed in this way by the ad blockers, in the way that they see subsequent calls for video payload in a CSAI model. As a result, program content is sometimes not able to reach the viewer, and the ad payload almost certainly isn’t.”
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