Digital Data Distribution Synchronization for Multi-Device Playback

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Solution Overview

Problem

Conventional systems face challenges in maintaining frame synchronization when new reproduction devices connect during continuous content distribution, leading to frame skipping and gradual loss of synchronization during lengthy reproduction.

Innovation Solution

A digital data distribution device generates and transmits clock pulses and frame synchronization data, while the reproduction device uses counters and comparators to adjust clock frequency for precise synchronization, ensuring that all devices remain synchronized without frame skipping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional frame synchronization using a frame synchronization signal on a digital bus is used, then synchronization can be established when distribution starts after all reproduction devices are in receiving mode, but synchronization cannot be established when new reproduction devices connect during continuous distribution

Engineering Contradiction:

Improveframe synchronizationVSAvoiddevice connection flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The transmitting-side device generates and transmits reference time information (elapsed time from content start) and frame number information in advance with the content data. This preliminary provision of synchronization data allows reproduction devices to establish synchronization immediately upon connection, regardless of when they join the distribution

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention uses digital copies of time and frame information (reference time information and frame number information) that are transmitted alongside content data. These digital copies enable reproduction devices to replicate the synchronization state of the transmitting device, ensuring consistent timing across all devices even when they connect at different times

Inventive Principle:

Principle #26Copying

2Reliability

If conventional frame synchronization is used, then initial synchronization can be achieved, but frame skipping occurs when synchronization is lost and then recovered

Engineering Contradiction:

Improveframe synchronizationVSAvoidsynchronization recovery

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The reproduction device continuously compares its internally generated frame number information with the reference frame number information received from the transmitting device. This feedback mechanism detects synchronization deviations and triggers corrective actions to realign the frame timing, preventing frame skipping during recovery

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The invention replaces the mechanical frame synchronization signal approach with a digital information-based system. Instead of relying on timing signals that can be lost, the system uses transmitted frame number data that can be continuously compared and used to recalculate synchronization, enabling smooth recovery without mechanical frame skipping

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If conventional frame synchronization is used, then short-term synchronization can be maintained, but gradual loss of frame synchronization occurs during lengthy reproduction

Engineering Contradiction:

Improveframe synchronizationVSAvoidreproduction duration

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The transmitting device generates reference time information based on elapsed time from content start and transmits it periodically with content data. This preliminary and continuous provision of time reference allows reproduction devices to continuously correct their internal timing, preventing gradual drift during lengthy reproduction

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the synchronization approach from fixed frame-based timing to dynamic time-based timing. By using elapsed time information as a parameter that updates continuously, the system can adapt to long-duration playback and maintain synchronization accuracy throughout the entire reproduction period

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10171710B2Device and method for digital data distribution, device and method for digital data reproduction, synchronized reproduction system, program, and recording medium

Publication Date: 2019.01.01 MITSUBISHI ELECTRIC CORP

AI summary

In order to eliminate timing offset between reproduction devices when a content transmitted from a distribution device is received and reproduced by a plurality of reproduction devices, data (SCR) indicating the elapsed time from the start of the content, generated by counting clock pulses, and data (FCR) indicating a frame number generated by counting the number of frames reproduced by a decoder (54) are transmitted by the distribution device, and a clock generation unit (103) in each reproduction device is controlled so that data (STC) indicating the elapsed time and data (FTC) indicating the frame number, which are generated in the same manner by each reproduction device, match the transmitted data (SCR, FCR). Synchronization between reproduction devices can thereby be established even when, in a state in which a content is being reproduced by one reproduction device, another reproduction device subsequently connects to the distribution device.