Bluetooth Multi-Channel Audio Synchronization via Timestamping
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Solution Overview
Problem
Existing Bluetooth protocols face challenges in synchronizing multiple-channel data streams, particularly in achieving low latency and high-quality audio transmission over Bluetooth links, which is essential for applications like surround sound recording and playback.
Innovation Solution
The proposed solution involves a method where a source device with multiple sensors captures and timestamps multiple data streams, which are then transmitted over Bluetooth to a target device. The target device synchronizes these data streams using the timing information, enabling accurate synchronization of surround sound audio with video capture, even in complex multi-channel scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If HFP protocol is used for audio input, then low latency is achieved, but only single-channel (mono) data transfer is supported
Solution Approach 1:
The patent segments the audio data transmission by creating separate data paths for different channels within the HFP protocol framework. Each microphone channel is assigned a specific data stream with dedicated timing information, allowing multi-channel transmission while maintaining the low-latency characteristics of HFP.
Solution Approach 2:
The patent adds a temporal dimension to the data transmission by incorporating precise timing information with each data packet. This enables the receiver to reconstruct synchronized multi-channel audio streams by sorting and timing-aligning packets from different channels, effectively transforming single-channel sequential transmission into multi-channel simultaneous transmission.
2Manufacturing precision
If A2DP protocol is used for audio output, then high-quality audio transmission is achieved, but increased latency and synchronization difficulty occur
Solution Approach 1:
The patent applies preliminary timing stamps to each audio packet at the source device before transmission. This preliminary action allows the receiving device to pre-calculate synchronization points and buffer management strategies, reducing the need for post-reception processing and minimizing overall latency while maintaining high audio quality.
Solution Approach 2:
The patent replaces the traditional mechanical buffering and synchronization approach with a timestamp-based temporal mapping system. Instead of relying on fixed buffer sizes and mechanical delay lines, the system uses software-based timestamp comparison and dynamic packet reordering, which reduces latency and improves synchronization accuracy.
3Productivity
If L2CAP packets are scheduled asynchronously for flexibility, then bandwidth efficiency is improved, but jitter increases and synchronization becomes difficult
Solution Approach 1:
The patent implements a feedback mechanism where the receiving device monitors the arrival times of packets with timestamps and dynamically adjusts its buffering strategy. When jitter is detected, the system automatically modifies buffer sizes and reordering thresholds, maintaining synchronization reliability while preserving the bandwidth efficiency of asynchronous L2CAP transmission.
Solution Approach 2:
The patent dynamically changes the timing parameters and buffer thresholds based on observed network conditions and packet arrival patterns. By adjusting synchronization tolerances and buffer management parameters in real-time, the system maintains reliable synchronization despite the variable timing inherent in asynchronous L2CAP packet scheduling.
Data Source
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AI summary
Processes, methods, systems, and devices are disclosed for synchronizing multiple wireless data streams captured in action by various sensors, with lost data recovery. For example, a source device may have multiple sensors acquiring data and sending the data streams (e.g., via Bluetooth connections) to a target device. Timing information may be appended for each of the data streams. Data packets of the multiple data streams may be formed with the timing information. The data packets may be transmitted to a target device that is configured to synchronize the multiple data streams using the timing information. The target device, applying the example processes or techniques of this disclosure, may accurately synchronize the multiple data streams. In some cases, the target device may capture additional data streams and the processor synchronizes all data streams of both the source and the target devices.