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Android Smartphone as a Microphonein SmartRoom System
Pavel Y. Kovyrshin, Dmitry G. Korzun
Petrozavodsk State UniversityDepartment of Computer Science
Grant KA179 “Complex development of regional cooperation in the fieldof open ICT innovations” of Karelia ENPI CBC programme 2007–2013 of the European Union,the Russian Federation and the Republic of Finland
15th FRUCT ConferenceApril 24, 2014, St.-Petersburg, Russia
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SmartRoom System Services
Centralized data storage (SIB: Semantic Information Broker)Many mobile clients
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Microphone-service: High Level Architecture
JNI - enables Java to usenative implementations
SmartSlog - provides API forSmart Space interaction
JSpeex - audio processingJava module
DatagramSocket - Javaimplementation of UDP protocol
User Datagram Protocol (UDP) is more suitable for such streamingapplications like Microphone-service.
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Microphone-service: Knowledge Processor
Service is implemented as a single KPSmartSlog: SDK for KP developmentOntology: service representation model (OWL, RDF)
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Microphone-service: Workflow Scheme
1 Initialization
2 Publishing address
3 Listening for connections
4 Receiving andprocessing data
5 Playing audio flow
Development: Microphone-service KP (server) and Client KP
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Android Client: Architecture
User interface Java-basedmodule uses Android SDK
JNI enables Java to usenative implementations
Application logic is C writtenand supported by Android NDK
SmartSlog supportsontology-driven implementation:
I publication and extraction dataI subscription mechanismI connection state tracking
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Android Client for SmartRoom: User Interface
Mobile device becomes a microphoneUsers: current speaker and chairman
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Performance ExperimentsWireless network quality strongly influences on service performance.
Network transmissionAudio processing
Average Standard deviationτ̄ = 50 ms σ = 6 ms ≈ 15 ms
Figure: Transmission time of 500 UDP packets of 62 bytes
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Performance: Our Solutions
Audio processing: JSpeex codecI based on CELP algorithmI well-suited to handle VoIPI suitable for unreliable transfer packets network
UDP for real-time audio transferRouter configuration: selection of less used network channel
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Metrics of Implementation
Client side Server sideJava code, loc. 138 293C code, loc. 91 84Devices Samsung Galaxy S3 Notebook Asus x200ca
D-Link DIR-320 routerTools SmartSlog SDK, JSpeex
Android SDK/NDK, JNI
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Conclusion
Released server (Linux) and client (Android) KPs
Performance: solutions and experimental evaluation
SourceForge:http://sourceforge.net/projects/smartroom/
files/services/microphone-service/
Project Wiki:http://oss.fruct.org/wiki/SmartRoom
Android client:http://play.google.com/store/apps/details
?id=petrsu.smartroom.android.srclient
My e-mail: [email protected]
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