Slave Audio Sync via Codec Clock Offset
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Solution Overview
Problem
Traditional Wi-Fi streaming systems face challenges in achieving low inter-channel time differences necessary for accurate stereo and 3D audio synchronization, leading to spatial audio localization issues due to temporally varying synchronization errors.
Innovation Solution
A method where slave devices request synchronization information from a master device based on audio codec clocks and Time Synchronization Function (TSF) times, allowing for adaptive synchronization requests and dynamic master allocation to minimize playback timing errors, with the master device transmitting synchronization information only upon request.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Wi-Fi streaming synchronization schemes are used, then network compatibility and ease of operation are maintained, but inter-channel time difference precision deteriorates (exceeding 100 µs acceptable threshold)
Solution Approach 1:
The patent replaces traditional NTP-based time synchronization with audio codec clock-based synchronization. Instead of relying on network time protocols and timestamp comparisons, the system uses the actual audio playback clocks from codec devices to determine synchronization offset, achieving higher precision (within 100 µs) by substituting a more direct measurement mechanism.
Solution Approach 2:
The master device acts as an intermediary that collects audio codec clock information from slave devices, calculates the synchronization offset, and provides correction data to slaves. This intermediary approach enables precise synchronization without requiring complex peer-to-peer coordination between all devices.
2Reliability
If master device continuously transmits synchronization information to all slave devices, then synchronization reliability is improved, but network bandwidth consumption and master device processing load increase
Solution Approach 1:
Instead of continuous transmission, the system uses event-driven periodic action where the master device transmits synchronization information only when slave devices request it or when synchronization conditions change. This reduces unnecessary network traffic while maintaining synchronization reliability through on-demand updates.
Solution Approach 2:
Slave devices autonomously determine when they need synchronization by monitoring their own playback status and requesting synchronization information from the master device only when necessary. This self-service approach reduces the burden on the master device and minimizes network bandwidth consumption compared to continuous broadcasting.
3Adaptability or versatility
If slave devices autonomously request synchronization information, then synchronization adaptability to local conditions is improved, but communication overhead and protocol complexity increase
Solution Approach 1:
Slave devices autonomously monitor their own synchronization status and independently decide when to request synchronization information from the master device. This self-service mechanism allows each slave to adapt to its local playback conditions without requiring complex centralized control, improving adaptability while keeping protocol logic relatively simple.
Data Source
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AI summary
The invention provides a method for synchronizing playback of audio and/or video from a source in a network of a plurality of separate devices in a computer network session. Especially, separate audio devices arranged for playing respective channels of a multi-channel audio stream. A master device serves to provide synchronization information regarding the audio and/or video playback to one or more slave devices. The slave device transmits a request for synchronization information to the master device. Thus, the slave device initiates synchronization rather than the master device. The master device transmits in response synchronization information to the slave device, and by receipt of this information, the slave device can synchronize playback of audio and/or video accordingly. Preferably, the synchronization information is based on audio codec clock based on Time Synchronization Function (TSF) time, e.g. by determining an offset between master and slave audio codec clocks. Since the slave device requests synchronization, the slave device can decide when to request synchronization according to one or more criteria, and the master device is relieved from the task of keeping track on when to transmit synchronization information to a plurality of slave devices.