AV1 Video Encoding Standard and BILIAV1 Self-Developed Encoder

AV1 is an open, royalty-free video encoding standard developed by the Alliance for Open Media (AOM). It was finalized in March 2018 and offers approximately 20% lower bitrate than H.265/HEVC at the same quality level. Major industry players like Google, Netflix, Meta, and Amazon have promoted AV1's adoption. By 2020, AMD, Intel, and Nvidia had released AV1 hardware decoders, and MediaTek, Qualcomm, and Apple had integrated AV1 support into their flagship chips. Software decoders like dav1d provide real-time decoding capabilities on mainstream platforms.

BILIAV1, Bilibili's self-developed AV1 encoder, began development in October 2020. The team chose to build from scratch rather than use existing open-source projects like Libaom or Intel's SVT-AV1 due to architectural limitations. The encoder achieved 19.6% lower bitrate than SVT-AV1 1.7.0 preset 7 at the same speed, and 15% lower bitrate than SVT-AV1 1.7.0 preset 6 at the same speed. Key development areas included TRACE system for debugging, parallel design for performance, and fast algorithms for efficiency.

AV1's technical innovations include superblock-based block partitioning, iterative prediction techniques, recursive transform search, and advanced loop filters. BILIAV1's engineering focused on TRACE systems for debugging, parallel processing across multiple dimensions, and optimized assembly implementations. Future plans include enhancing performance for point-to-point (P2P) streaming and expanding to live streaming applications.