dav1d vs libaom: AV1 Decoder Speed Comparison

The open-source dav1d decoder, developed by VideoLAN and FFmpeg, is significantly faster than the original AOMedia reference decoder, libaom. While libaom served as the proof-of-concept software implementation during the development of the AV1 video standard, dav1d was built from the ground up for high-performance production environments. Depending on hardware architecture, thread counts, and video resolution, dav1d is typically between 2 to 5 times faster than libaom, making real-time AV1 software playback viable on standard consumer hardware.

Single-Thread Performance

In single-threaded benchmarks, dav1d generally outperforms libaom by a factor of 2x to 3x. On modern x86-64 processors utilizing AVX2 or AVX-512 instruction sets, dav1d can process 1080p and 4K frames in less than half the time required by libaom.

This performance gap is even more pronounced on ARM architectures. On mobile and low-power devices utilizing ARM64 NEON instructions, dav1d regularly achieves speedups exceeding 2.5x to 3.5x over libaom's native decoding routines, which direct-translates to lower battery consumption and fewer dropped frames.

Multi-Thread Scaling

The performance divide widens considerably when multi-threading is enabled. While libaom relies on conventional tile-based and frame-based threading models that exhibit diminishing returns as core counts increase, dav1d uses a fine-grained, asynchronous frame and tile threading architecture.

On desktop and server processors with 8 or more cores:

• 4K Decoding: dav1d can reach speeds between 3x and 5x faster than libaom.
• 1080p Decoding: dav1d routinely hits speeds 2.5x to 4x faster than libaom.
• Core Utilization: dav1d maintains near-linear scaling up to 16 threads, whereas libaom frequently plateaus earlier due to synchronization bottlenecks.

Architectural Advantages Behind the Speedup

The performance advantage of dav1d is primarily driven by three technical factors:

1. Handwritten Assembly: While libaom relies heavily on standard C code with select compiler intrinsics, dav1d features hand-tuned assembly code written specifically for AVX2, AVX-512, and ARM NEON pipelines.
2. Reduced Memory Footprint: dav1d requires roughly one-third to one-fourth of the memory bandwidth and RAM allocation that libaom demands. Lower memory overhead prevents cache misses and allows modern CPU caches to keep decoded frame data close to execution units.
3. Optimized Loop Filters: AV1 utilizes complex in-loop filtering processes—such as the Deblocking Filter, Constrained Directional Enhancement Filter (CDEF), and Loop Restoration. dav1d streamlines these filters into optimized, parallelized pipelines, drastically reducing per-pixel processing latency.

Practical Impact

Before dav1d, software decoding of high-bitrate 4K 60fps AV1 content via libaom was nearly impossible on standard desktop CPUs without dropping significant numbers of frames. With dav1d, software decoding at 4K 60fps is achievable on mid-range quad-core and hexa-core processors, allowing platforms like YouTube, Netflix, and major web browsers to roll out AV1 streams to billions of devices that lack dedicated AV1 hardware acceleration chips.