Master-Slave Streaming Media Synchronization
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Solution Overview
Problem
Streaming media systems with multiple output devices often experience time-related distortion due to differences in crystal oscillator frequencies and temperatures, leading to synchronization issues between playback devices, which can result in out-of-sync audio and video across different locations.
Innovation Solution
A method and apparatus for synchronizing streaming media playback across multiple output devices by designating one device as the 'master' and others as 'slaves', where the master device controls the data flow rate to maintain a nominal buffer fill level, and slave devices adjust their playback rates accordingly to match the master's rate, using techniques such as adjusting the control voltage of a voltage-controlled oscillator or modifying data samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple output devices are used to deliver media to different locations, then the system's versatility and coverage are improved, but time-related distortion and synchronization issues occur due to variations in crystal oscillator frequencies and temperatures
Solution Approach 1:
The system divides the media delivery network into master and slave output devices. The master device independently receives and plays back media, while slave devices receive media from the master and adjust their playback to match the master's timing. This segmentation allows multiple devices to operate independently yet remain synchronized, resolving the contradiction between versatility and synchronization reliability.
Solution Approach 2:
Slave output devices monitor their buffer fill levels and adjust their playback rates based on feedback from the master device's playback timing. The slave devices continuously compare their playback progress with the master and make real-time adjustments to maintain synchronization, ensuring reliable synchronized playback across multiple versatile output devices.
2Ease of operation
If each output device operates independently with its own crystal oscillator, then device autonomy and configurability are improved, but frequency variations cause playback rate differences and desynchronization
Solution Approach 1:
The system creates a common timing reference level by having all slave devices synchronize to the master device's playback rate. Despite each device having its own crystal oscillator with potentially different frequencies, the synchronization mechanism ensures all devices operate at the same effective playback rate, eliminating timing discrepancies and achieving equipotential playback timing across the network.
Solution Approach 2:
Slave output devices dynamically adjust their playback rate parameters based on the master device's timing. By changing the playback rate parameter in real-time to match the master, slave devices compensate for crystal oscillator frequency variations and maintain precise timing accuracy despite independent operation.
3Reliability
If slave devices adjust their playback rates to match the master, then synchronization is improved, but buffer management complexity increases due to rate adjustments
Solution Approach 1:
The buffer management system dynamically adjusts playback rates based on real-time buffer fill level conditions. When the buffer is sufficiently full, slave devices can play at normal rate; when the buffer level changes, the playback rate is dynamically adjusted to prevent underflow or overflow. This dynamic approach maintains synchronization while managing buffer complexity through adaptive control.
Solution Approach 2:
Each slave output device autonomously manages its own buffer and playback rate adjustment without requiring external intervention. The slave devices independently monitor their buffer levels and self-adjust their playback timing to match the master, simplifying the overall system architecture while maintaining synchronization reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures average timing synchronization of playback across multiple output devices, maintaining a synchronized media presentation despite variations in crystal oscillator frequencies and temperatures, thereby enhancing the user experience by preventing audio and video desynchronization.
Implementation Method 1
adjusting the control voltage of a voltage-controlled oscillator
Data Source
AI summary
A method and apparatus for synchronizing streaming media with multiple output devices. One or more media servers serve media streams to one or more output devices (i.e., players). For playback synchronization, one output device is the “master”, whereas the remaining output devices are “slaves”. More data is requested from the media server by the “master” device to maintain a nominal buffer fill level over time. The “slave” devices receive streamed data from the media server at the rate determined by the master device's data requests, and the average rate of data flow over the streaming network is thus controlled by the frequency of the single “master” device's crystal. “Slave” devices make playback rate corrections to maintain respective buffer fill levels within upper and lower threshold levels. For slow networks, each media data packet timestamp is calculated from the time the master's buffer reaches nominal level.