Multi-Device Audio Playback Sync Without Shared Clock Hardware
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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 playback synchronization across multiple devices is achieved, but device cost and hardware 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 data over a network, and execution devices adjust their playback using software-controlled sample rate conversion and buffer management, eliminating the need for specialized hardware synchronization components.
Solution Approach 2:
The patent introduces a distribution device as an intermediary that coordinates playback across multiple execution devices. This mediator sends timing information, sample rate data, and synchronization commands over a network, allowing devices to synchronize without direct hardware coupling or shared oscillators.
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 replaces physical voltage controlled crystal oscillator hardware with software-based clock rate adjustment mechanisms. Execution devices receive target sample rate information from the distribution device and use software algorithms to adjust their playback clock rates, eliminating the need for additional hardware components and reducing device space requirements.
3Adaptability or versatility
If independent clocking is used in execution devices, then device independence and flexibility are maintained, but playback synchronization becomes difficult
Solution Approach 1:
The patent implements feedback mechanisms where execution devices send timing information and playback status back to the distribution device. The distribution device uses this feedback to adjust timing information and synchronization commands, allowing independently clocked devices to maintain synchronization through continuous adaptive adjustment rather than rigid hardware coupling.
Solution Approach 2:
The patent makes the synchronization system dynamic by allowing execution devices to adjust their sample rates and buffer sizes in real-time based on incoming timing information from the distribution device. This dynamic adaptation enables independently clocked devices to synchronize their playback without requiring fixed hardware synchronization mechanisms.
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.