Does librav1e support real-time AV1 encoding?

This article explores whether the librav1e library supports real-time AV1 video encoding for live streaming applications. We examine how its speed settings, CPU requirements, and performance characteristics determine its viability for live, low-latency broadcasts compared to other encoding alternatives.

The Short Answer: Yes, But With Conditions

Yes, librav1e (the C-compatible API wrapper for the Rust-based rav1e encoder) supports real-time encoding, but its viability depends heavily on your hardware, video resolution, and chosen speed preset.

While the AV1 codec is notoriously resource-intensive, rav1e was designed with safety and speed in mind. By configuring the encoder to its fastest settings, you can achieve the frame rates required for live streaming.

Speed Presets and Real-Time Performance

The core of rav1e’s real-time capability lies in its speed presets, which range from 0 (slowest, highest quality) to 10 (fastest, lowest quality).

• Presets 0 to 4: Designed for offline, high-quality archival encoding. These are too slow for live streaming.
• Presets 5 to 7: Balanced options that may achieve real-time speeds on high-end server CPUs or at lower resolutions (like 720p).
• Presets 8 to 10: Specifically optimized for real-time encoding. Preset 10 sacrifices some compression efficiency to maximize encoding speed, making 1080p60 live streaming possible on modern consumer CPUs.

System Resource Requirements

Because AV1 compression algorithms are highly complex, real-time encoding with librav1e demands substantial processing power.

• Multi-threading: rav1e features robust multi-threading capabilities. To stream in real-time at 1080p, a modern multi-core processor (such as an AMD Ryzen 9 or Intel Core i9 with 12+ threads) is highly recommended.
• Resolution Limits: For standard consumer hardware, real-time encoding is often limited to 720p at 30fps or 60fps. Attempting 4K real-time software encoding on standard hardware with librav1e is currently impractical.

librav1e vs. Other Live AV1 Encoders

While librav1e can handle live streaming, it may not always be the optimal choice depending on your system architecture:

1. SVT-AV1: Developed by Intel and Netflix, SVT-AV1 is currently the industry standard for CPU-based (software) AV1 encoding. It generally offers superior multi-core scaling and higher efficiency than rav1e at real-time speeds.
2. Hardware Encoders (NVENC / QuickSync): For dedicated live streaming PCs, hardware-accelerated AV1 encoding (found in NVIDIA RTX 40-series, AMD RX 7000-series, and Intel Arc GPUs) is vastly superior to any software encoder. Hardware encoding offloads 100% of the work from the CPU, allowing for flawless 4K60 streaming with virtually zero latency.

Best Use Cases for librav1e in Live Streaming

Despite the competition, librav1e is highly valuable in specific scenarios:

• WebRTC Applications: Its integration into WebRTC ecosystems makes it a strong candidate for low-latency, peer-to-peer video conferencing.
• Rust Ecosystems: If your streaming pipeline is built using Rust, rav1e offers memory safety guarantees that C-based encoders cannot match.
• Embedded and Linux Systems: librav1e provides a lightweight, highly compatible library format that integrates easily into custom Linux-based streaming hardware.