Real-time Audio Streaming Solution for Language Learning Application
Techstack collaborated with a Berlin-based partner to enhance their language learning application with real-time audio streaming capabilities. The application allows users to practice foreign languages through AI conversation, offering grammar suggestions, vocabulary recommendations, and interactive lessons. Our team was tasked with implementing smooth, real-time audio streaming in the React Native app to enable seamless playback of dynamically generated PCM audio chunks from the backend.
Industry:
EdTech
Services:
Mobile Development
Location:
Germany
Challenge
The implementation of real-time audio streaming presented several technical hurdles:
1. Audio continuity: Ensuring smooth playback without glitches or "clicking" noises when new audio chunks arrive rapidly.
2. Dynamic playback management: Maintaining a consistent audio queue while allowing dynamic updates to playback speed.
3. Stream completion detection: Detecting the exact end of streaming without relying on empty queues, which could trigger false end events.
4. Cross-platform performance: Integrating native iOS audio APIs with React Native in a performant way.
Solution
Our team developed a comprehensive audio streaming solution specifically tailored to the requirements of the language learning application:
Implemented a native iOS audio bridge using AVAudioEngine and AVAudioPlayerNode with a timePitch unit for dynamic playback speed adjustments
Designed a sophisticated queuing system where audio chunks are stored and merged into buffers to prevent gaps or glitches
Created a tracking mechanism that monitors the number of buffers currently playing
Implemented a closeStream signal system to accurately detect the end of streaming
Built a bridge between the native iOS implementation and the React Native framework
Technologies Used
We used Swift, SwiftUI, React Native, and AVAudioEngine to create a powerful real-time audio streaming system, combining native iOS performance with seamless cross-platform integration for a smooth learning experience.
The workflow
The implementation process followed several key stages, from architectural analysis and native audio design to full integration, optimization, and performance testing.
Architecture & requirements analysis
Analysis of the existing React Native application architecture and audio requirements.
Native audio bridge design
Design of the native audio bridge solution using Swift.
Key feature development
Implementation of the AVAudioEngine with buffer management system.
Playback speed control integration
Integration of the timePitch unit for variable playback speeds.
React native bridge development
Development of the React Native bridge components.
Stream completion detection setup
Implementation of the stream completion detection mechanism.
Performance testing & optimization
Performance testing and optimization.
About the team
The development was performed by Techstack's cross-platform mobile development specialists with expertise in both React Native and native iOS development using Swift.
Impact
The streaming solution delivered significant improvements to the language learning application:
Reduced audio output wait time from several seconds to near real-time
Improved user experience and engagement for TTS-based chat and voice assistant features
Achieved near-zero playback glitches based on performance metrics
Maintained consistent latency under 150ms per audio chunk
Enhanced the overall responsiveness of the language learning application's audio features