SounDroid: Supporting Real-Time Sound Applications on Commodity Mobile Devices

Abstract

A variety of advantages from sounds such as measurement and accessibility introduces a new opportunity for mobile applications to offer broad types of interesting, valuable functionalities, supporting a richer user experience. However, in spite of the growing interests on mobile sound applications, few or no works have been done in focusing on managing an audio device effectively. More specifically, their low level of real-time capability for audio resources makes it challenging to satisfy tight timing requirements of mobile sound applications, e.g., a high sensing rate of acoustic sensing applications. To address this problem, this work presents the SounDroid framework, an audio device management framework for real-time audio requests from mobile sound applications. The design of SounDroid is based on the requirement analysis of audio requests as well as an understanding of the audio playback procedure including the audio request scheduling and dispatching on Android. It then incorporates both real-time audio request scheduling algorithms, called EDF-V and AFDS, and dispatching optimization techniques into mobile platforms, and thus improves the quality-ofservice of mobile sound applications. Our experimental results with the prototype implementation of SounDroid demonstrate that it is able to enhance scheduling performance for audio requests, compared to traditional mechanisms (by up to 40% improvement), while allowing deterministic dispatching latency.

Can Android Run on Time? Extending and Measuring the Android Platform's Timeliness

“…Use Cases: There are many use cases where real-time audio processing becomes necessary. For example, latency estimation is necessary for coordinated playback across multiple mobile devices as envisioned previously [13,14]. Similarly, directional audio in museum exhibitions [4,8] allows for a better user experience for users.…”

“…Playback. This application is inspired by existing work that proposes a class of audio mobile applications [13,14]. One example shows surround sound playback from a set of mobile devices, recreating the surround sound experience in mobile scenarios and others.…”

“…SounDroid [14] outlined two main challenges of real-time audio management in Android: (i) tight timing requirement of audio requests and (ii) unpredictable dispatching latency for audio playback and record. It addressed these two problems via SounDroid framework APIs, which provide customized earliest deadline first scheduling and acoustic frequency division scheduling for audio requests and device buffer padding for unpredictable device latency.…”

“…Our approach is pragmatic-we have identified a small number of target applications and extend the platform to support those well. These applications include personalized healthcare (e.g., a cochlear implant) [2], audio-based indoor localization [15], harmonized sound reproduction [13], timely sound delivery [14], and UAV flight control [3]. We have also deployed our system on a wind turbine for blade health monitoring [18].…”