Audio Device Buffer Control for Synchronous Playback

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Solution Overview

Problem

Audio devices struggle to reproduce audio signals synchronously due to differences in transmission methods, such as wireless and wired transmission, leading to desynchronization.

Innovation Solution

An audio system comprising a master device and slave devices connected through a network, where the master device converts high-quality audio signals into medium-quality signals, using buffers to manage latency and ensure synchronized reproduction across all devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If different transmission methods (wireless and wired) are used to transmit audio signals from master device to slave devices, then transmission flexibility and adaptability are improved, but synchronization between devices deteriorates due to performance differences in transmission ways

Engineering Contradiction:
Improvetransmission flexibilityVSAvoidsynchronization
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The master device calculates transmission times for different transmission methods in advance and pre-adjusts the audio signal timing. By performing preliminary timing adjustment based on pre-calculated transmission times, the system compensates for transmission method differences before signal delivery, ensuring synchronized reproduction across devices using different transmission channels

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the timing parameter of audio signals based on transmission method. The master device adjusts the reproduction timing of audio signals according to the calculated transmission time differences between wireless and wired transmission, dynamically modifying the time parameter to achieve synchronization despite different transmission characteristics

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If audio signals are transmitted through multiple transmission ways simultaneously, then system versatility is improved, but latency differences cause desynchronization

Engineering Contradiction:
Improvetransmission method diversityVSAvoidlatency difference
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The master device performs preliminary calculation of transmission times for each transmission method and pre-adjusts audio signal timing accordingly. By calculating and compensating for latency differences before transmission, the system ensures that signals arriving through different channels are synchronized at the playback devices

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The master device creates multiple copies of the audio signal for different transmission channels, with each copy adjusted according to its specific transmission time characteristics. Each slave device receives a tailored copy optimized for its transmission method, ensuring synchronized reproduction despite different transmission paths

Inventive Principle:
Principle #26Copying

Data Source

PatentEP3313088B1Audio device, audio system, and synchronous playback method
Publication Date: 2024.01.17 YAMAHA CORP
  • EP3313088B1 patent drawingFigure 1
  • EP3313088B1 patent drawingFigure 2
  • EP3313088B1 patent drawingFigure 3A~3B

AI summary

An audio device (10) is provided with a signal input portion (21) that inputs an audio signal, a memory (230, 240) that temporarily stores the audio signal that has been input to the signal input portion (21), a first output portion (25) that reads and outputs the audio signal from the memory (230, 240), a second output portion (26) that reads and outputs the audio signal from the memory (230, 240), and a buffer control portion (231, 232, 241, 242) that performs write control of the audio signal with respect to the memory (230, 240) and read control of the audio signal from the memory (230, 240). The buffer control portion (231, 232, 241, 242) sets a second reading position being a reading position of the audio signal with respect to the second output portion (26) to a position that precedes by a delay time a first reading position being a reading position of the audio signal with respect to the first output portion (25), and, when starting output of the audio signal, writes silent data for the delay time with respect to the memory (230, 240) and sets the first reading position at a head of the silent data.