Remote Media Playback Synchronization Using Global Time Offsets

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Solution Overview

Problem

Current methods for sharing media items across multiple remote devices fail to support remote synchronization and real-time, synchronized experiencing due to issues like Bluetooth range limitations, device clock inaccuracies, and the need for special credentials, leading to unsynchronized playback.

Innovation Solution

A system comprising a source device, target devices, and a synchronization server that determines average latencies for each device to calculate a global time offset for synchronized playback, using sync information and sync notifications to ensure media items are played in sync across devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If Bluetooth connection is used to send media items between devices, then media sharing is enabled, but synchronization accuracy deteriorates due to range limitations and connection instability

Engineering Contradiction:
Improvemedia sharing capabilityVSAvoidsynchronization accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces a synchronization server as an intermediary component that receives latency measurements from all devices and calculates a global time offset. This mediator coordinates the synchronization process across multiple devices, eliminating the need for direct peer-to-peer timing coordination that fails over Bluetooth. The server acts as a central reference point that all devices can independently synchronize to, ensuring accurate synchronization even when devices are outside Bluetooth range of each other.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If streaming methods are used to share media across remote devices, then remote access is enabled, but synchronization accuracy deteriorates due to device clock inaccuracies

Engineering Contradiction:
Improveremote device accessVSAvoidplayback synchronization
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where each device measures its own latency to the synchronization server and reports this information back. The server uses this feedback to calculate individual global time offsets for each device, compensating for variations in device clock accuracy and network latency. This closed-loop feedback system continuously adjusts synchronization parameters to maintain accurate playback timing across all remote devices.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the synchronization parameter from using individual device clocks (which have varying inaccuracies) to using a global time offset calculated by the synchronization server. By transforming the reference from local, inaccurate clocks to a centralized time reference, the system achieves consistent synchronization across all devices regardless of their individual clock accuracy or geographic location.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If special credentials are required for target devices to access media items, then security is improved, but synchronization performance deteriorates due to access delays

Engineering Contradiction:
Improvemedia access securityVSAvoidmedia playback speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent performs authentication and credential verification in advance, before the actual media playback begins. The synchronization server handles the security checks and latency measurements during an initial setup phase, establishing the global time offset beforehand. This preliminary authentication ensures security requirements are met while avoiding delays during the actual playback, as the access permissions are already confirmed and the synchronization parameters are pre-calculated.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3504881B1System and method for synchronized playing of media items on a plurality of remote devices
Publication Date: 2025.12.03 DEEZER SA
  • EP3504881B1 patent drawingFigure 1
  • EP3504881B1 patent drawingFigure 2A
  • EP3504881B1 patent drawingFigure 2B

AI summary

Generally, a method and system for synchronized playing of a streamed media item on multiple remote devices are provided. The system may comprise a source device arranged to play and stream a media item and arranged to select at least one target device with which to share the media item thereof. The system may comprise a synchronization server in communication with the source device and with the at least one target device. The synchronization server may be arranged to: (i) determine a source average latency for the source device and a target average latency for each of the at least one target device; and (ii) determine, for each of the at least one target device, based on the source average latency and the respective target device's target average latency, a global time offset usable to synchronize playing of the media item thereof up to a predetermined accuracy.