TECHNICAL
Optimising Video QoE in the Age of Adaptive Streaming ANALYSIS
Rethinking the transcoding pipeline for a bandwidth-constrained, IP-first world
Dr. Anthony Basham FSCTE elaborates on the recent Cires21/VisualOn whitepaper, contextualising insights in a wider broadband industry context and exploring what content- adaptive transcoding optimisation will mean for operators going from broadcast television delivery to IP video delivery.
So, the challenge is a bit more than just expanding bandwidth. Operators are now left with no choice but to optimise every stage of delivery for efficiency. In that context, transcoding has transformed from a backend technical function into a strategic network capability.
From broadcast to IP The shift from traditional broadcast distribution to IP-based streaming is revolutionising the broadband market at its core. Video traffic has become by far the largest driver of usage on both conventional and mobile networks, challenging operators’ long-held capacity planning principles and creating new needs not only for more data capacity but also for optimising efficiency across the video delivery chain. For a long time, network strategy has largely been based on the belief that increasing bandwidth would be the natural solution to quality issues. That assumption is increasingly difficult to hold up. In competitive environments, as streaming traffic continues to scale across fibre, DOCSIS, Wi-Fi, and mobile networks, operators are coming to the realisation that customer experience is now driven not only by throughput. Quality of Experience (QoE) increasingly depends less on Ethernet throughput than it does on how elegantly and intelligently video is encoded, adapted and then delivered to those users under the highly variable conditions found in the real world. This direction of travel is consistently supported by industry forecasts. Cisco Visual Networking Index forecast that up to 82% of all consumer IP traffic would be video, and the Ericsson Mobility Report continues to report that video is now the main driver behind mobile traffic growth. In reality, broadband networks are evolving into video networks. With operators increasingly migrating from legacy systems based on DVB and RF to IP-based architectures, this transition is gaining further momentum. With the industry’s long-term path toward IPTV and OTT aggregation and app- based television delivery, peak time video traffic is no longer contained to managed broadcast domains. Instead, it flows progressively over more common broadband infrastructure, resulting in persistent stress on access, aggregation, metro and core layers at the same time.
From Bandwidth to Experience
Adaptive bitrate (ABR) streaming is the foundation of today, as it can dynamically adapt streams to changing network conditions, device capabilities and available throughput. But ABR streaming is only as strong as the bitrate ladder behind it. If the performance of lower bitrate tiers is subpar, users processing under adverse conditions will see things like macro blocking, buffering events, on-screen artefacts, and erratic playback behaviour. This matters especially as the physical viewing experience for many users is often not dictated by those premium 4K tiers, but rather the middle and lower rungs of the ladder. The two most common situations are mobile network users, overloaded Wi-Fi environments, and broadband subscribers and households with shared bandwidth often hanging between 360p and 576p resolution levels. For many real-world cases, these lower tiers are the real experience. This is a key mindset shift for broadband players. The industry has long been obsessed with pushing the peak quality capabilities of UHD, HDR and premium sports delivery. While those are still commercially relevant differentiators, the biggest practical QoE gains might arise from improving what could be referred to as the “quality floor”: the minimum viewing experience that’s acceptable when operating at limited resources. Thus, the next video quality phase will not be marked by resolution increases only, but stable and perceptually relevant quality delivered at scale across highly divergent use-cases.
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