Multi-Device Audio Stream Delay Calibration for AV Synchronization
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Solution Overview
Problem
Network-based interactive systems face challenges in synchronizing audio playback across multiple audio devices with varying codec delays, leading to misalignment between video and audio frames, especially in scenarios involving multiple participants using different wireless audio devices.
Innovation Solution
Determine and calibrate codec delay values for multiple audio devices, selecting a base codec delay value and adjusting other devices accordingly to optimize synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple audio devices with different codec delays are used in network-based interactive systems, then device compatibility and user choice are improved, but audio synchronization between video and audio frames deteriorates
Solution Approach 1:
The system performs preliminary calibration by determining codec delay values for each audio device before actual audio playback. A calibration audio stream is transmitted to each device, and the system measures the actual playback time by comparing transmitted timestamps with received timestamps. This preliminary measurement allows the system to calculate and store calibration delay values that will be used to compensate for device-specific delays during normal operation, thereby preventing synchronization issues before they occur.
Solution Approach 2:
The system dynamically adjusts the audio playback time parameter based on the measured codec delay values for each device. By changing the playback time parameter individually for each audio device according to its specific delay characteristics, the system maintains synchronized audio-video playback across multiple devices with different codec delays, thus resolving the synchronization problem while preserving device compatibility.
2Manufacturing precision
If codec delay values are calibrated for each audio device, then audio synchronization is improved, but system complexity and processing time increase
Solution Approach 1:
Each audio device independently determines its own codec delay value through the calibration process. The system transmits a calibration audio stream with timestamps, and each device autonomously measures its playback delay by comparing timestamps and calculating the difference. This self-service approach eliminates the need for complex centralized calibration procedures and reduces system complexity, as each device contributes to its own synchronization calibration.
Solution Approach 2:
The system implements a feedback mechanism where each audio device reports its measured codec delay value back to the system. Based on this feedback, the system calculates the appropriate calibration delay and adjusts the audio playback time for each device. This feedback loop enables automatic synchronization calibration without requiring manual intervention or complex system-wide coordination, thereby managing system complexity while achieving precise audio synchronization.
3Manufacturing precision
If audio playback time is adjusted for calibration, then audio-video synchronization is improved, but audio latency may increase
Solution Approach 1:
The system applies different audio playback time adjustments (calibration delays) to different audio devices based on their individual codec delay characteristics. Instead of using a uniform delay adjustment for all devices, the system tailors the calibration delay to each specific device's needs. This localized approach ensures that each device receives the minimum necessary delay adjustment to achieve synchronization, thereby minimizing overall audio latency while maintaining audio-video synchronization.
Data Source
AI summary
Techniques are described herein for audio processing. For instance, a technique can include determining a plurality of coder-decoder (codec) delay values for a plurality of audio devices, wherein each codec delay value is associated with at least one audio device of the plurality of audio devices, selecting a first codec delay value from the plurality of codec delay values, wherein the first codec delay value is associated with a first audio device of the plurality of audio devices, selecting, for a second audio device of the plurality of audio devices, a second codec delay value from a plurality of codec delay values associated with the second audio device, determining a calibration time delay between the first codec delay value and the second codec delay value, and outputting the calibration time delay.