Wireless Audio Frame Synchronization via Hash Matching
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Solution Overview
Problem
Existing wireless communication systems face challenges in synchronizing audio streams across multiple independent receiver nodes to achieve precise timing for optimal stereo sound, as they lack a common clock to coordinate left and right audio signals within the required 48 KHz sampling frequency and 20 μs synchronization tolerance.
Innovation Solution
The method involves applying a hash algorithm to data frames in wireless receiver devices to match sequences of hash values from a control stream, allowing independent synchronization of audio streams by decoding and rendering audio when hash values match, and using a Bluetooth® clock to align audio channels within the required timing tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple independent receiver nodes receive audio streams via separate wireless communication links, then wireless audio transmission is enabled, but synchronization between left and right audio channels cannot be achieved within the required 20 μs tolerance
Solution Approach 1:
A master receiver node is introduced as an intermediary that receives the audio stream, generates a control stream containing hash values and timing information, and transmits it to slave receiver nodes. This intermediary enables synchronization across independent wireless links by providing a common reference that all nodes can use to align their audio playback timing within the required 20 μs tolerance.
Solution Approach 2:
The system implements a feedback mechanism where the master receiver node processes incoming audio frames, generates hash values representing the audio content, and transmits these hash values in a control stream to slave nodes. The slave nodes compare received hash values with locally computed hash values to determine synchronization status and adjust their playback timing accordingly, ensuring synchronized audio output across all receiver nodes.
2Device complexity
If each receiver node independently processes audio frames without a common clock, then device complexity is reduced, but timing synchronization between multiple receiver devices cannot be achieved
Solution Approach 1:
The master receiver node serves as a mediator that establishes a common timing reference for all slave nodes without requiring them to share hardware clocks. The master node generates a control stream containing hash values and timing information that slave nodes use to synchronize their audio processing and playback, maintaining device independence while achieving precise timing synchronization within 20 μs tolerance.
Solution Approach 2:
The system uses hash values as a digital copy or fingerprint of the audio content that can be transmitted separately from the audio data itself. Each receiver node independently computes hash values from received audio frames and compares them with hash values in the control stream, enabling synchronization through information copying rather than direct hardware clock sharing.
3Adaptability or versatility
If audio data is transmitted over separate wireless links to multiple receiver devices, then distributed audio playback is enabled, but frame alignment across different Bluetooth clocks cannot be achieved
Solution Approach 1:
The master receiver node acts as an intermediary that receives audio frames over the wireless link, processes them to generate hash values and timing information, and distributes this control information to slave nodes. This intermediary approach enables distributed audio playback across multiple devices with independent Bluetooth clocks by providing a common reference framework that all nodes can use to achieve frame alignment within the required precision.
Solution Approach 2:
The system replaces the mechanical approach of sharing a common hardware clock across all receiver nodes with an information-based synchronization mechanism. Instead of synchronizing physical clock signals, the system transmits hash values and timing information through data streams, allowing independent receiver nodes to achieve frame alignment through software-based comparison and adjustment of their local processing timing.
Data Source
AI summary
Systems, methods, and devices synchronize data streams by hashing received data frames to generate a sequence of hash values, comparing the generated hash value sequence to a hash value sequence received in a control stream, and processing data frames when the hash value sequences match. A source device and multiple receiver devices may synchronize audio data encoded in data frames, applying a hash function to each data frame to generate a first sequence of hash values, transmitting the data frames on a first channel and the first sequence of hash values on a control channel, receiving the data frames and the first sequence of hash values in the receiver devices, applying the hash algorithm to received data frames to generate a second sequence of hash values, comparing the first and second sequences of hash values, and processing data frames when the first and second sequences of hash values match.