Abstract—Wave Field Synthesis is a method producing sound that uses arrays of closely placed speakers. This creates an unique challenge for distributed playback systems. Because of clock frequency drift, the playback must constantly be corrected via interpolation and shifting in time of the played stream. In this paper a new approach to network based audio playback synchronization is presented, that makes heavy use of the PTP network time synchronization protocol and ALSA Linux audio subsystem. The software does not need any specialized hardware and can approximate precisely how the playback stream should be interpolated via a set of statistical indicators. The evaluation shows that the difference between two devices playing audio using the presented system is under 10 μs for 99 % of the time, which fully satisfies the requirements of Wave Field Synthesis. The system was compared to other network audio synchronization systems available currently: NetJack2, RAVENNA and Snapcast, all of which had from 10 to 50 times higher differences between two devices than the presented system. 

Index Terms—network, signal processing, audio, synchronization, linux

Cite: Szymon Mikulicz, "Precise Inter-Device Audio Playback Synchronization for Linux," International Journal of Signal Processing Systems, Vol. 9, No. 3, pp. 17-21, September 2021. doi: 10.18178/ijsps.9.3.17-21