Audio Playback Synchronization by Frame Sample Adjustment
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Solution Overview
Problem
Conventional methods for synchronizing digital content playback across multiple devices are limited by the inherent differences in clock frequencies of crystal oscillators, requiring expensive hardware and additional space.
Innovation Solution
A distribution device maintains a clock rate and distributes tasks with time stamps, adjusting the number of samples per frame to synchronize operations among independently clocked digital data processing devices without a voltage controlled crystal oscillator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional synchronization methods using voltage controlled crystal oscillators are employed, then playback synchronization is achieved, but device cost and complexity increase
Solution Approach 1:
The patent replaces the mechanical/electrical voltage controlled crystal oscillator system with a software-based solution. The distribution device sends timing information and sample rate adjustment instructions to execution devices, which then adjust their playback accordingly. This substitutes complex hardware synchronization mechanisms with software-controlled timing and resampling algorithms.
Solution Approach 2:
The patent changes the operating parameters of the execution devices by dynamically adjusting the sample rate of digital content. Instead of forcing all devices to run at the same clock frequency, the system allows each device to operate at its native clock rate while adjusting the content parameters (sample rate) to achieve synchronization. This is done by interpolating or decimating samples to match the target playback timing.
2Reliability
If voltage controlled crystal oscillators are used for synchronization, then clock rate matching is achieved, but device space requirements increase
Solution Approach 1:
The patent eliminates the need for physical voltage controlled crystal oscillator hardware by using software-based timing control. The distribution device communicates timing information through data packets, and execution devices adjust their playback timing through software resampling algorithms, completely removing the need for additional hardware components and the space they would occupy.
3Device complexity
If independent clocking is used in execution devices, then device simplicity is maintained, but playback synchronization deteriorates
Solution Approach 1:
The patent introduces timing information packets as an intermediary between the distribution device and execution devices. These packets contain synchronization data that allows independently clocked devices to coordinate their playback. The intermediary carries timing references that execution devices use to adjust their sample rates and synchronize with the master clock without requiring complex hardware interconnections.
Solution Approach 2:
The patent allows execution devices to maintain their simple independent clocking architecture while dynamically changing the sample rate parameter of the digital content being played back. By adjusting the number of samples played per clock cycle, the system achieves synchronization without requiring the execution devices to change their fundamental clocking architecture or add complex synchronization hardware.
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.