​HEVC versus AV1: Telestream Has A View

NAB will see heated debate over the attributes and potential of codec schemes for UHD, streaming and next-gen data intense applications. We asked Telestream for a view on this and Matthew Rehrer, Product Management at the company has responded with some insightful comments.

BroadcastBridge: How successful has been the uptake of HEVC? Aside from needing a licence what other issues might be making adoption of HEVC problematic?

Telestream’s Rehrer: Despite a lot of public discourse around licensing, content distributors have never cited licensing as a primary concern with this technology. Rather, demand at the viewer level for premium UHD and HDR viewing experiences on their mobile devices will push adoption. We’re not seeing that demand yet.

Hardware decoding has often been cited as a critical factor for delivering a consistent viewing experience and, most importantly for preserving battery life on mobile devices. HEVC requires a lot of compute power: while it offers great compression benefits, it is hard on the viewing device. HEVC offers no meaningful benefit if it sucks the life out of viewers’ devices. The nexus of primary benefitfor HEVC, one could argue, is bandwidth constrained mobile networks and wireless devices so a critical mass of support for hardware decoding in mobile devices will gate wide deployment.

For now, both consumption of and support for H.264 is so broad that most content producers aren’t ready to turn away from it. Instead, they’re making a choice between delivering H.264 or delivering H.264 and HEVC. There isn’t yet a strong impetus to replace H.264.

Aside from being royalty free, what is the key advantage of AV1 in your view? In what way is its potential better than HEVC?

AV1 is being designed to hit stringent efficiency targets. If successful, it is possible that AV1 will achieve equivalent quality to HEVC at lower bitrates. A very intangible, but perhaps more important, factor to consider is impact of the Alliance for Open Media. The Alliance has done an excellent job of attracting stakeholders who have historically backed opposing Codec initiatives. Once deploying AV1 becomes practical, it has the potential to be even more widely agreed upon, adopted and promoted than H.264. The influence of the Alliance for Open Media will certainly have an impact on the adoption of one codec over another.

At NAB we will may see some side by side tests of AV1 versus VP9 and HEVC. Is Telestream showing AV1 product?

AV1 and VP9 performance or dramatic comparisons/demonstrations of their performance are unlikely to affect HEVC royalty costs. Demonstrations that focus on efficiency or quality over compression compute cost/efficiency and decode support are not particularly useful since the impact on the viewing device is the really meaningful factor. Telestream is interested in developing technology solutions that enable a quality viewing experience for end users.

What does Apple’s endorsement of HEVC and AV1 mean?

Apple’s support is important for both codecs due to the sheer volume and value of the player clients Apple influences. For this reason, I would expect peak adoption for content distributors to be relatively high for both, but especially for AV1. Peak HEVC adoption may still ultimately be lower than H.264 and targeted at mobile efficiency and UHD HDR services. Peak AV1 adoption is perhaps 6-10 years in the future but has the potential to eclipse H.264 on a market percentage basis.

What is best in the long run for HDR UHD online – HEVC or AV1 or another codec? Is any codec better at UHD in your opinion?

I expect that, at first, HEVC will be the best choice due to compression compute cost and decoder client support. However, if AV1 ultimately fulfills all of its potential for quality and decoder adoption while steadily improving compression compute cost, it will ultimately be the best codec for UHD and larger resolutions for HDR as well as wider color gamut and higher dynamic range content in the more distant future. For now, the compute-cost-to-quality ratio of AV1 is wildly asymmetric – currently more than 1000x more expensive than HEVC.

How is the industry likely to encode video over 5G networks?

The era of the 5G network will likely see the highest usage of H.264 yet – as well as the highest usage of HEVC. 5G may still be in use when AV1 reaches peak usage, however mobile data technology lifecycles are rapid enough that we may be into a notional 6G era before AV1 usage matures. The life cycle of video codec technology with the adoption rates of MPEG-1, MPEG-2, H.264 and expected adoption rates for HEVC and AV1 are much longer. For example, H.264 has dominated the entire 3G and 4G eras. It is not uncommon for the generational cycle of a mobile data network to span approximately 10 years. By contrast a codec lifecycle can easily span multiple decades.

How important is it that the industry develop a new codec for massive data?

The current CODEC roadmap or H.264, HEVC and AV1 seems primed to support the transition to VR, UHD and beyond. 

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