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26 March 2020

Global bandwidth constraints could accelerate AV1 uptake

Last week was a tale of solidarity in the communications world with North American operators rallying together in a 60-day grace period to protect subscribers, particularly the most vulnerable. Days later, the US OTT video giants responded to calls from European top dogs by implementing bitrate reductions to alleviate network traffic. End users will hardly notice, but will there be ramifications for the technology distribution chain?

Should lockdowns become more stringent in the US, just as they have escalated dramatically in Europe over the past two weeks, then sweeping video bitrate reductions are likely to become commonplace globally. Latin American service providers have already lumped pressure on the streaming majors to commit to bandwidth reductions, while India’s Cellular Operators Association has made similar pleas. But, as Netflix alluded to in a statement, this is not as simple as turning a dial.

Netflix, Amazon Prime Video, YouTube, Disney+, Apple TV+, Facebook and many more have all committed to bitrate squeezes for the next 30 days across Europe to help ease the continent’s now monolithic traffic load. Tier 1 providers typically build in-house CDNs, often supported by mainstream CDNs, giving them extra control of what is delivered and how it is delivered. These companies can bring in extra compression clout, roll out more encoders, more edge caching capabilities, or more niche bandwidth-crunching techniques like P2P networking, but the ISP situation is a little trickier.

Providing some clarity while fishing for a little sympathy, Netflix suggested in a statement that the job of helping to reduce global network traffic is not a simple task for its Open Connect CDN program, in part because of the way ISPs around the world have built their networks in different ways and operate within different constraints.

“Building a residential ISP network in a dense metropolitan area is quite a different prospect from building a residential ISP network in a sparsely populated rural area. Some ISPs build their networks with a substantial amount of excess capacity (“headroom”) others do not. Fortunately, we have a lot of experience delivering Netflix efficiently through our Open Connect program – as well as other technologies we’ve pioneered – and so we can respond to these different scenarios quickly,” read a statement from Netflix.

Open Connect was founded in 2011 with the fundamental aim of reducing traffic load on networks and therefore bringing better video quality to subscribers. Netflix designed a directed caching system with efficiency gains over standard on-demand-driven CDNs – to reduce overall demand on upstream network capacity by several orders of magnitude.

In February, Faultline described how adoption of the AV1 codec was set to skyrocket after Netflix added AV1 support on Android smartphones via a new Data Saving feature. Only select titles are available to stream in AV1, which got us thinking that perhaps Netflix is busy encoding a larger share of its library in AV1 to reduce bandwidth congestion, although the company may be setting its priorities on less intensive tasks and unfortunately did not respond to our request for comment. Netflix has reported 20% compression efficiency gains over VP9 by replacing it with AV1, however, AV1 decoding is 30% more complex than VP9 or AVC.

If indeed Netflix is planning to accelerate its use of AV1, then support for Apple devices may come sooner than expected and rival streaming service providers may be encouraged to follow suit. However, Apple’s Safari browser still does not support VP9, while YouTube itself does not support HEVC 4K streaming, meaning no YouTube 4K video streaming for Safari users.

Netflix’s AV1 Android rollout follows on from its work with VP9, released as part of its mobile encodes in 2016 and further optimized with shot-based encodes in 2018. After deploying per-title encoding in 2015, this shot-based encoding framework, called Dynamic Optimizer, gave Netflix capabilities for more granular optimizations with a video stream.

Netflix and the other streaming services are targeting a 25% traffic reduction in Europe and will respond to other regions appropriately if and when they receive the call to arms from local authorities.

Conscious of subscribers demanding refunds, Netflix has reassured its customer base that they will still receive the packages they paid for. Subscribers to UHD, HD or SD packages will be delivered content in the promised quality, so what Netflix has done is remove the highest bandwidth stream in each category. YouTube has taken a more drastic approach, which of course it can afford to as a free service, by reducing all streams to SD across the EU by default. We understand this applies to all networks.

Disney has been more drastic still – delaying its launch in France until April 7. French Disney fans must feel a little hard done by considering Disney+ stuck firm with its UK launch, going live on Tuesday this week. However, as seen late last year with the US launch of Disney+, technical issues plagued the service as the floodgates opened to some 10 million sign ups within two hours – and that was without the added traffic loads that networks today are burdened with.

Disney and the ISPs will therefore be eager to avoid a repeat situation in Europe with critical communications a priority at this time, although it still isn’t clear why Disney singled out France.

As of writing, the UK’s most popular free TV streaming platform BBC iPlayer has not followed suit, including for the Britbox venture jointly run with ITV. “We have not reduced or restricted our highest-quality streams on BritBox, which are full high-definition, but will keep the situation under review including any official guidance or feedback from partners and suppliers,” said a BBC spokesperson.

That said, British Telecom has flexed its muscles, saying that – despite experiencing weekday daytime network traffic spiking by between 35% to 60% – it is “nowhere near” capacity and this figure is still about half of what it handles during peak times. BT should be wary of tempting fate, particularly given its embarrassing recent WiFi faux pas.