AsTree - An Audio Subscription Architecture Enabling Massive-Scale Multi-Party Conferencing

Learn about AsTree, an innovative audio subscription architecture designed to enable massive-scale multi-party conferencing, in this 15-minute conference presentation from NSDI '25. Discover how ByteDance engineers addressed the significant network challenges posed by audio subscription in global multi-party video conferencing systems, particularly when scaling to massive participant counts. Explore the limitations of traditional strategies that subscribe to all remote participants, including signaling storms, excessive bandwidth consumption, and resource strain on both server and client sides. Understand the technical design of AsTree's cascading tree topology and media plane-based audio selection mechanisms that dramatically reduce signaling messages and audio stream forwarding requirements. Examine real-world deployment results from the Lark conferencing platform, which demonstrate over 30% reduction in audio stall ratios, more than 50% reduction in video stall ratios, and 40% fewer negative client reviews, providing concrete evidence of AsTree's effectiveness in improving user experience at scale.