Audio Playback Synchronization Across Independently Clocked Devices
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Solution Overview
Problem
Conventional methods for synchronizing digital content playback across multiple audio and/or audiovisual devices are limited by the inherent differences in clock frequencies, requiring expensive hardware and additional space, necessitating a solution for synchronizing operations without a voltage-controlled crystal oscillator.
Innovation Solution
A distribution device maintains a clock rate and distributes tasks with time stamps to a group of execution devices, allowing each device to adjust the number of samples per frame to synchronize playback, enabling synchronization among independently clocked digital data processing devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional synchronization methods using voltage controlled crystal oscillators are employed, then clock frequency differences between devices can be compensated, but hardware cost and device complexity increase significantly
Solution Approach 1:
The patent replaces the mechanical/electrical voltage controlled crystal oscillator system with a software-based solution. Execution devices use timestamp information from distributed tasks to calculate and adjust their playback timing, eliminating the need for complex hardware synchronization components while maintaining synchronization accuracy across independently clocked devices.
Solution Approach 2:
The patent introduces timestamp information as an intermediary mechanism. Instead of directly controlling clock frequencies through hardware, the distribution device embeds timing information in task data, which execution devices then use to synchronize their operations. This intermediary approach simplifies hardware requirements while achieving reliable synchronization.
2Reliability
If voltage controlled crystal oscillators are used for synchronization, then clock rate differences can be managed, but additional hardware space is required
Solution Approach 1:
The patent eliminates the physical voltage controlled crystal oscillator component by replacing it with software-based timestamp processing. Execution devices determine playback timing through computational adjustment of sample rates based on timestamp data, requiring no additional hardware space beyond the standard processing unit.
3Ease of manufacture
If independent clocking is used in each device, then device simplicity and manufacturing ease improve, but synchronization between devices deteriorates
Solution Approach 1:
The patent segments the synchronization function into two independent parts: the distribution device generates and embeds timestamp information in task data, while execution devices independently process these timestamps to determine their playback timing. This segmentation allows each device to remain simple and independently manufacturable while achieving reliable synchronization through their interaction.
Solution Approach 2:
The patent implements a feedback mechanism where execution devices use the embedded timestamp information to adjust their playback timing. The timestamp acts as feedback that allows each independently manufactured device to self-correct its timing to match the synchronized schedule, maintaining synchronization reliability without compromising manufacturing simplicity.
Data Source
AI summary
Example systems, apparatus, and methods receive audio information including a plurality of frames from a source device, wherein each frame of the plurality of frames includes one or more audio samples and a time stamp indicating when to play the one or more audio samples of the respective frame. In an example, the time stamp is updated for each of the plurality of frames using a time differential value determined between clock information received from the source device and clock information associated with the device. The updated time stamp is stored for each of the plurality of frames, and the audio information is output based on the plurality of frames and associated updated time stamps. A number of samples per frame to be output is adjusted based on a comparison between the updated time stamp for the frame and a predicted time value for play back of the frame.