Improving networked music performance systems using application-network collaboration

摘要

Networked Music Performance (NMP) systems involve musicians located in different placeswho perform music while staying synchronized via the Internet. The maximum end-to-end delayin NMP applications is called Ensemble Performance Threshold (EPT) and should be less than25 milliseconds. Due to this constraint, NMPs require ultra–low-delay solutions for audio coding,network transmission, relaying, and decoding, each one a challenging task on its own. Thereare two directions for study in the related work referring to the NMP systems. From the audioperspective, researchers experiment on low-delay encoders and transmission patterns, aiming toreduce the processing delay of the audio transmission, but they ignore the network performance.On the other hand, network-oriented researchers try to reduce the network delay, which contributesto reduced end-to-end delay. In our proposed approach, we introduce an integration ofdynamic audio and network configuration to satisfy the EPT constraint. The basic idea is that, themajor components participating in anNMPsystem, the application and the network interact duringthe live music performance. As the network delay increases, the network tries to equalize itby modifying the routing behavior using Software-Defined Networking principles. If the networkdelay exceeds a maximum affordable threshold, the network reacts by informing the applicationto change the audio processing pattern to overcome the delay increase, resulting in belowEPT end-to-end delay. A full prototype of the proposed system was implemented and extensivelyevaluated in an emulated environment.