Network music performance with ultra-low-delay audio coding under unreliable network conditions

A key issue for successfully interconnecting musicians in real-time over the Internet is minimizing the end-to-end signal delay for transmission and coding. Anyhow, the variance of transmission delay ('jitter') occasionally causes some packets arrive too late for playback. To avoid this problem previous approaches are working with rather large receive buffers while accepting larger delay. In this paper the authors will present a novel solution that keeps buffer sizes and delay minimal. On the network layer the authors are using a highly optimized audio framework called 'Soundjack' and on the coding layer the authors are working with an ultra low-delay codec for high-quality audio. The authors analyze and evaluate a modified transmission and coding scheme for the Fraunhofer Ultra-Low-Delay (ULD) audio coder, which is designed to be more resilient to lost and late arriving data packets.