Adopting AV1 for Real-Time Communication (RTC) at Scale - Engineering at Meta

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By Yu-Chen (Eric) Sun, Jie Dong, Kewei Huang, Dave Jack, Joachim Reiersen, Phil Scherbel, Karthik Sekuru, Vertika Singh, Thileepan Subramaniam, Wei Zhou

Adopting AV1 for real-time communication at Meta has been a multi-year effort spanning codec selection, device eligibility, rate control, and error resilience.

We’re sharing the technical and operational challenges while deploying AV1 and expanding coverage, and how we addressed them for real-time communication.

We’re presenting several technologies for improving AV1 call quality, including rate control and error resilience.

The AV1 video codec, first standardized by AOMedia in 2018, has rapidly evolved and gained widespread industry support. Today, leading companies like YouTube, Netflix, and Meta stream video using AV1 at scale. Meta introduced AV1 for real-time video calls on high-end devices in 2023, aiming to deliver superior call quality. Since then, we have made notable progress in expanding AV1’s reach and improving the experience for AV1-powered calls. Today, AV1 is enabled on the majority of mobile devices in Meta Real-Time Communication (RTC) applications such as Messenger and WhatsApp.

Why Is Meta Interested in Adopting AV1 for RTC?

The motivation for switching to a more advanced video codec is straightforward — it delivers the same visual quality while using much less bandwidth. In offline tests, we observed at least a 20% bitrate reduction with AV1 compared with H.264/AVC under our product settings on low-end and mid-range devices. If devices can accommodate higher encoding complexity, the bitrate reductions are even greater. For real-time video calls, this means people on slower or limited networks can enjoy significantly better video quality. This is important to our users because, to meet low-latency requirements, the RTC product must handle bitrate fluctuations. In real-world networks — especially in emerging markets — video bitrates for RTC products typically range from 10 kbps to 400 kbps. Maintaining good video quality below 100 kbps remains challenging.

To evaluate the user experience across codecs, we enabled AV1 in the Messenger app and conducted a side-by-side comparison using two Android phones. In the examples below, AV1 is displayed on the right and H.264/AVC on the left, both limited to 100 kbps. The H.264/AVC video appears noticeably blurry, while the AV1 video remains much clearer — highlighting the significant advantage of AV1 for video calls under bandwidth constraints.

https://engineering.fb.com/wp-content/uploads/2026/06/Meta-AV1-RTC-Demo.mp4

H.264/AVC (left) versus AV1 (right).

An increased focus on screen content, needs support from high-quality computer generated content encoding. Traditionally, video encoders aren’t that well suited to complex content such as text with a lot of high-frequency content, and people are very sensitive to reading blurry text. AV1 has a set of coding tools — palette mode and intra-block copy — that drastically improve performance for screen content.

Palette mode is designed according to the observation that the pixel values in a screen-content frame usually concentrate on the limited number of color values. It can represent the screen content efficiently by signaling the color clusters instead of the quantized transform-domain coefficients. In addition, for typical screen content, repetitive patterns can usually be found within the same picture. Intra-block copy facilitates block prediction within the same frame, so that the compression efficiency can be improved significantly. AV1 has the benefit of providing these two tools at the main profile.

The Challenges in Adopting AV1

While the comparison clearly illustrates AV1’s advantages, there are significant challenges to its adoption in RTC. Unlike video on demand (VOD), RTC systems must manage end-to-end video latency, which ideally should remain below 300 milliseconds. If latency exceeds this threshold, people begin to notice delays in the conversation.

Maintaining both high video quality and low latency is challenging. For example, multi-pass encoding techniques — which can improve quality — introduce additional delay. On the decoder side, extensive buffering further increases latency. Additionally, any sudden spikes in bitrate can cause video freezes during calls, degrading the user experience.

RTC products must also dynamically adapt to network conditions during a call. Two challenges are fluctuations in network bandwidth and packet loss.To cope with bandwidth changes, the video encoder adjusts parameters such as resolution and frame rate. However, switching resolutions typically requires a new key frame, which can cause a sudden bitrate spike and temporary video freezing. Similarly, packet loss can trigger retransmissions or force the encoder to send another key frame, both of which may lead to video freezes. Effectively...