Android VoIP SDK
Android VoIP SDK enables rapid development of mobile apps using our Android VoIP software with standard algorithms easily configured for Android VoIP client and server applications.
- Native Android library with API
- Optimized performance for DSP and ARM platforms
- Narrowband and wideband voice codecs available
- Echo and noise solutions for superior speech
- Full featured VoIP telephony
VOCAL’s Android VoIP SDK library is modular with source code optimized for DSPs and ARM processors from TI, ADI and other leading vendors. Our Android software development kit and library supports a range of ETSI ITU IEEE compliant algorithms including VoIP codecs, echo cancellation and noise reduction algorithms to develop a variety of internet calling apps. Our expertise in development and configuration of mobile, network and telephony products will speed your Android VoIP software application to market. Contact us to discuss your specific Android VoIP application development requirements. Custom solutions are also available.
Features
- Mobile SIP stack supports Android VoIP client server applications
- Supports G.711, G.722, G.729, Silk, Opus and other wideband voice codecs
- Acoustic echo cancellation, noise reduction, dereverberation and beamforming available
- Device configuration and provisioning using TR-069 management protocols available
- Supports multi-tasking and multichannel operations
- TTY / TDD option available
- Supports full and half duplex modes
- Supports multiple VoIP internet services
Applications
- Android VoIP client
- Mobile VoIP internet calling
- Audio and video conferencing
- VoIP game communications
- TTY / TDD calling
- Fax over IP
- PTT and Radio over IP
Android Library
VOCAL’s Android Library allows mobile VoIP developers to quickly implement interactive games and apps using standard algorithms easily configured for Android VoIP client server applications. Our Android software development kit is easily installed in a standard IDE as a native Android library. The Android VoIP SDK is provided as a C/C++ Android library with support for:
- Android API class library interface
- Native SIP stack with adaptive jitter
- VoIP codecs for narrowband and wideband speech and audio
- Voice quality enhancement with acoustic echo cancellation, noise reduction and dereverberation
- Acoustic beamforming for microphone noise reduction
Android API
For those that require maximum performance for custom Android applications, such as games and conferencing, our software development kit includes an Android API Class with the JNI (Java Native Interface) which provides ready access to the optimized code in VOCAL’s Android vocoder library. Our Android library and API Class have been implemented using the Android NDK for building compatible libraries in C or C++. The Android SDK provides development tools to include our optimized C code in your custom apps via the Java API class.
Android SIP Stack
The native Android SIP stack provides access to the vocoders in the Android Library and incorporates an adaptive jitter algorithm to further enhance voice quality. The proprietary jitter algorithm adapts rapidly to packet loss or delays from congested networks and is exceptional at maintaining constant voice output for the listener.
Our native SIP stack and VoIP protocols implement an Android SIP client with full support for VoIP Internet calling services using SIP and RTP. Video conferencing and streaming are also supported with RTP. In addition, VoIP encryption using SRTP or TCP with SSL / TLS is available to ensure secure communication between Android SIP client server applications.
Android Vocoders
Although the Android platform includes basic GSM telephony capabilities, VOCAL’s Android library includes a range of standard ITU and GSM, Wideband and other standard Android vocoders. In addition, the low bit rate MELP / MELPe (Mixed-Excitation Linear Predictive / enhanced) vocoders and the OPUS Audio Codec are available. Developers should evaluate the characteristics of each Android voice codec algorithm and its suitability for a particular custom Android application and/or platform. Please contact VOCAL to discuss other Android VoIP codec options that are available for Android SIP client custom applications development.
Android vocoders may be selected and configured to tailor an Android SIP client for different user requirements and operating environments. The native library structure allows the developer to include only the desired Android vocoder and support packages, thus minimizing memory requirements for the application package files (.apks) ultimately deployed to targeted mobile devices.
The following Android vocoder modules are currently available for mobile Android VoIP client applications.
- G.711 – 64k bps PCM (A-law or μ-law form)
- G.722 – 7 kHz audio coding within 64 kbit/s (SB-ADPCM)
- G.722.1 – 24k and 32k bps, 7 kHz audio
- G.722.2 – Adaptive Multi-Rate Wideband (GSM AMR-WB)
- G.729AB – 8k bps CS-ACELP
- MELPe – 600 bps / 1200 bps / 2400 bps
- Speex – 8 kHz, 16 kHz, and 32 kHz CELP
- SILK – Variable Bitrate Wideband Speech Codec
- OPUS – 8kHz to 48kHz audio with dual layer LP and MDCT encoding
Voice Quality Enhancement
The Native Android VoIP software library includes VOCAL’s voice quality enhancement system with Android echo cancellation, noise reduction, and speech dereverberation algorithms optimized for the architecture. In hands-free voice communications using Android, echo cancellation removes reflected copies of a direct path wave from the acoustic/mechanical coupling between the speaker and microphone in the device; dereverberation handles speech reverberation or reflections from surfaces in an enclosed environment; while noise reduction reduces additive noise sources. All of these techniques contribute to significantly improved speech enhancement and intelligibility for the end user’s listening experience.
Acoustic Beamforming
The native Android library supports acoustic beamforming algorithms to capture the speaker’s voice in dynamic and challenging environments. Mobile devices are often used as hands-free systems with the speaker located some distance from the microphone. Newer Android devices with microphone arrays can use adaptive acoustic beamforming to enhance the speaker’s voice while rejecting interferes and background noise from other sources.
VOCAL’s solution is available for the above platforms. Please contact us for specific supported platforms.