Audio Clock Sync via Time Server Timestamp Exchange
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Solution Overview
Problem
Existing audio playback devices lack effective methods for synchronizing clocks across multiple devices for synchronized audio playback, leading to potential desynchronization issues during streamed audio delivery.
Innovation Solution
A method involving broadcast/multicast network communications between audio playback devices, a time server, and a synchronization agent, where timestamps are exchanged to update local clock times, ensuring all devices operate on the same time reference, utilizing DHCP messages and logical bus topologies like Ethernet or WiFi networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clock synchronization is implemented using existing methods, then audio playback can occur, but clock desynchronization occurs between multiple devices leading to playback issues
Solution Approach 1:
The patent introduces a time server as an intermediary component that mediates time synchronization between multiple audio playback devices. The time server receives timestamp packets from devices, determines accurate timestamps using system time or GPS, and sends corrected timestamps back to devices, thereby resolving clock desynchronization without requiring direct peer-to-peer synchronization between devices.
Solution Approach 2:
The patent implements a feedback mechanism where audio playback devices send timestamp packets to the time server indicating their current clock state, and the time server responds with corrected timestamps. This closed-loop feedback system continuously monitors and adjusts device clocks to maintain synchronization, preventing drift over time.
2Measurement precision
If timestamp exchange protocol is implemented, then clock synchronization accuracy improves to better than 30 microseconds, but network communication complexity increases
Solution Approach 1:
The patent implements a universal timestamp exchange protocol based on DHCP that can be used across different network configurations and device types. The same protocol works for both wired Ethernet and wireless WiFi networks, and can synchronize any number of devices, reducing the need for device-specific or network-specific synchronization implementations.
Solution Approach 2:
The timestamp synchronization protocol is designed to be self-configuring and automatic. Devices automatically send timestamp packets to the time server without manual configuration, and the time server automatically processes requests and sends corrections. The system self-adjusts to network conditions and device states, reducing the need for complex manual setup or intervention.
Data Source
AI summary
A method is provided for synchronizing clocks on a plurality of audio playback devices. The method includes receiving a broadcast/multicast acknowledgement packet from a synchronization agent at a first audio playback device of the plurality of audio playback devices. A first timestamp representing a time when the acknowledgement packet was received by the first audio playback device is recorded. A broadcast/multicast timestamp packet is received from a time server at the first audio playback device. The timestamp packet includes a second timestamp representing a time when the time server received the acknowledgement packet from the synchronization agent. A local clock time on the first audio playback device is updated based on the first timestamp and the second timestamp. The method enables clock synchronization among the plurality of audio playback devices for synchronized playback of streamed audio via the plurality of audio playback devices.