Can librav1e encode AVIF images effectively?

This article explores the viability of using the librav1e encoder for creating AVIF images. It examines the technical compatibility of the Rust-based rav1e library with the AVIF format, compares its performance and compression efficiency against industry-standard encoders like libaom, and provides a clear overview of when it is practical to use.

Technical Compatibility

AVIF (AV1 Image File Format) is an image format based on the AV1 video compression standard. Because rav1e is an encoder specifically designed for the AV1 format, it can technically be used to compress still images into AVIF.

Popular AVIF creation tools and libraries, such as libavif (via the avifenc command-line utility) and cavif, natively support librav1e as an underlying encoding backend. Users can select it over other encoders during the compilation or configuration phase of these tools.

Performance and Encoding Speed

One of the primary advantages of librav1e is its focus on speed and safety. Written in Rust, it utilizes modern CPU instruction sets and assembly optimizations to deliver fast encoding times.

When compared to the reference encoder libaom (AOMenc), librav1e often processes images much faster, especially at lower speed presets. This makes it an attractive option for real-time image encoding pipelines or server-side applications where low latency is critical.

Compression Efficiency and Quality

While librav1e excels in speed, it lags slightly behind libaom in terms of raw compression efficiency. For still images, the primary goal of AVIF is to achieve the smallest possible file size without sacrificing visual quality.

libaom has undergone extensive tuning specifically for still-picture encoding, allowing it to produce better visual fidelity at lower bitrates than librav1e. For static web assets where images are encoded once and served millions of times, the superior file size reduction of libaom usually outweighs the speed benefits of librav1e.

Conclusion and Recommendations

librav1e can be used effectively for encoding AVIF images, but its suitability depends on your specific use case:

• Use librav1e if you need to encode AVIF images on-the-fly, require fast processing speeds, or want to leverage Rust’s memory safety guarantees in your software stack.
• Avoid librav1e if your priority is achieving the absolute smallest file size for web delivery. In this scenario, libaom remains the more effective choice.