Synthesized Audio Clock Synchronization Without System Clock Drift
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Solution Overview
Problem
Existing methods for synchronized audio or video playback in peer-to-peer computer networks lack accuracy and require synchronization of system clocks or specialized hardware, leading to imprecise timing across devices.
Innovation Solution
The implementation of a virtual clock system that synchronizes audio/video devices without relying on primary system clocks, using a helper clock for extrapolation and sample rate adjustment, allowing direct synchronization between audio clocks and enabling precise timing without specialized hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If system clocks are synchronized across devices, then playback synchronization can be achieved, but synchronization accuracy deteriorates due to system clock drift and lack of precision
Solution Approach 1:
The patent introduces an audio clock as an intermediary timing reference that operates independently from system clocks. Each device generates its own audio clock based on the audio stream's sample rate, and synchronization is achieved by exchanging audio clock timestamps between devices. This intermediary audio clock mechanism eliminates direct dependence on imprecise system clocks while maintaining reliable synchronization across the network.
2Measurement precision
If specialized hardware is used for each node, then synchronization precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces specialized hardware clocking systems with a software-based audio clock synthesis approach. Instead of requiring dedicated hardware timers or clock generators at each node, the system uses the audio software pipeline to generate and synchronize timestamps. The audio clock is synthesized from the audio stream's sample rate information, eliminating the need for complex hardware while maintaining precise timing through software-controlled timestamp generation and exchange.
3Ease of operation
If system clock adjustments are made for synchronization, then playback coordination is improved, but audio quality deteriorates due to resampling and timing disruptions
Solution Approach 1:
The patent segments the timing function into two independent components: system clock operations and audio clock operations. The audio clock is derived separately from the audio stream's sample rate rather than being tied to system clock adjustments. This segmentation allows playback coordination to be achieved through audio clock timestamp exchange without disrupting the audio rendering pipeline, preventing resampling artifacts and timing disruptions that would otherwise degrade audio quality.
Data Source
AI summary
The invention provides a method for providing a synchronization in a computer network for synchronized playback of audio an/or video by a plurality of separate devices. Each separate device generates a virtual clock in response to a timing of the audio codec of a received audio stream. Especially, segmented time is used as reference time. Either the virtual clock is generated directly in response to the tick counter of the audio codec, or by a periodic measurement of the timing of the audio codec extrapolated by a monotonic clock. A sample rate converter may be used to slightly adjust the frequency of the virtual clock.