Synthesized Audio Clock Sync for Multi-Device Playback Timing
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Solution Overview
Problem
Existing methods for synchronized audio or video playback in peer-to-peer computer networks lack accuracy and often require synchronized system clocks or specialized hardware, leading to imprecise synchronization between 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 playback across multiple devices 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 limitations
Solution Approach 1:
The patent introduces an audio clock as an intermediary timing reference that operates independently of 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 rather than synchronizing system clocks directly. This intermediary audio clock mechanism resolves the contradiction by providing high-precision timing without relying on inaccurate system clock synchronization.
2Reliability
If specialized hardware is used for each node, then synchronization accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent enables each device to generate its own audio clock independently using software-based timing mechanisms that leverage the audio codec's inherent sample rate. Each device self-synchronizes by calculating its own audio clock timestamps and exchanging them with other devices over the network, eliminating the need for specialized hardware clock generators at each node. This self-service approach achieves high synchronization accuracy without increasing device complexity.
3Ease of operation
If system clock adjustments are made for synchronization, then playback can be coordinated, but audio quality deteriorates due to clock manipulation
Solution Approach 1:
The patent segments the timing function into two independent components: system clock for general operation and audio clock for precise audio playback timing. The audio clock is derived separately from the audio stream's sample rate and operates independently of system clock adjustments. This segmentation allows system clocks to be adjusted for coordination purposes while the audio clock maintains precise, unmanipulated timing for high-quality audio playback.
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.