Categories: Engineering

The AV1 video codec comes to Webex!

Thomas Davies & Sijia Chen – Webex is rolling out the AV1 video codec into production early next year. This will bring our media quality to the next level. As a founding member of AOM, Cisco is proud to introduce this advanced video technology into the real time communications market

It’s here! We have begun the process of rolling out the advanced AV1 video codec across Webex, taking video quality to the next level in the process, and replacing the aging H.264 standard.

Following on from our successful demonstration at the Big Apple conference last year, starting early next year, AV1 will be enabled on Webex when sharing high-motion content on desktop machines. This means that, when sharing the most challenging type of content into your meeting, such as a sports video, a commercial, or any type of high-motion graphics, the new AV1 codec will be available to help you share the very best quality possible.

What is AV1?

AV1 is a next-generation video codec, capable of greatly improving video quality. It was designed by the Alliance for Open Media to be a royalty-free technology, avoiding the patent wars that have stymied deployment of other advanced video codecs for nearly a decade.

Cisco is proud to be a founding member of AOM. You can find out more about how AOM and AV1 came to be – and how Cisco helped drive AV1 development – in these blogs.

What do I need to use AV1 in Webex?

Transmitting AV1 is supported when sharing screens or applications with “Optimize for motion and video” selected , and when the machine you are on has at least four cores. Receiving AV1 is supported for any machine with at least two cores. AV1 will automatically be used for sharing this type of screen content whenever all participants in a meeting support it, otherwise it will automatically revert to H.264.

How we are rolling out AV1

Adopting a brand-new video codec has an impact on every part of our Collaboration portfolio, so we are going step-by-step.

In future releases we will systematically expand where we deploy AV1. The immediate next steps are to support AV1 for other desktop share modes – either optimized for text and images, or automatically optimized. AV1 works just as well for these modes too, but we are being careful to change things gradually to make sure the user experience is perfect at each step.

Webex employs a fundamentally switched architecture, where video from each participant in a meeting is coded on their machine at different qualities and sent via a server to the other meeting participants. Initially, if some of those participants cannot support AV1 then we will automatically fall back to using H.264. Over time we will also remove these restrictions by applying ad hoc transcoding between AV1 and H.264 for those participants. This will also allow AV1 meetings to be recorded without reverting to H.264, for example.

Mobile devices will also rapidly gain hardware AV1 support, and then AV1 can be rolled out to mobile too. Although our solution is software-based and very fast on ARM as well as x86 processors, it is always better to make use of hardware codecs where possible on mobile to get the best battery life possible.

We’ll also be seeking to reduce the restrictions we have placed on core count for AV1 as we continue to optimize. In fact, remarkably, our AV1 solution uses little more CPU than H.264. However, there are a huge range of different machines out there, and again we are moving gradually to safeguard user experience.

Cisco’s AV1 solution

Powering our solution is a super-optimized software encoder. In designing it we had two goals: to provide significant benefits over H.264 and to do so at the smallest possible extra computational cost.

This is a pretty tall order. In non-real-time applications like streaming, it’s acceptable to increase encoding complexity by 2, 4, even 10 times in order to reap the benefits of a new standard. In real time communications, that’s not true: the machines our customers use, although getting more powerful over time, are also doing more and more.

The Cisco AV1 encoder is flexible, and it is designed to operate within a similar CPU footprint to H.264 and provide bigger quality improvements at lower bit rates when quality is even more precious.

Connecting our meetings, our server architecture must negotiate multiple codecs, resolutions and bitrates to suit all participants and respond to changing network conditions resiliently.

Our software also makes use of VideoLAN’s extremely fast dav1d open source AV1 decoder, a remarkable effort, which has had an enormous impact on accelerating the deployment of AV1.

The future: media quality and Cisco

This year has seen a steep increase  in usage of Collaboration technology, and people depend on it as never before. Media quality is central to improving our experience, and to deepening the connections we can make in our virtual lives, during the current crisis and beyond. AV1 is one part of a multi-pronged strategy to develop higher and higher quality real-time meeting experiences – in short, to make them 10x better. The aim is for AV1 to become the new normal, but also that the media that it encodes to become ever richer, more detailed, and more vibrant.

About the authors

Thomas Davies is a Principal Engineer in the Collaboration Technology Group. He has worked in satellite networking, RF communications, and broadcasting, but has spent most of his career on video and codecs. He has worked for Cisco for over 8 years on creating the next generation of collaboration experiences.

Sijia Chen is Technical Leader in the Collaboration Technology Group. She works on video-related features, including video codec algorithm design and implementations as well as video quality assessments and metrics. She has worked for Cisco for over 12 years on Webex Media Engine, which serves multiple Webex production lines.

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