Audio Codec Noise Synthesis During Inactive Phases

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Solution Overview

Problem

Current audio codecs fail to efficiently reduce transmission bitrate during inactive phases while maintaining noise generation quality, especially with increasing bitrate consumers and applications like mobile phones and wireless transmission broadcast.

Innovation Solution

An audio codec scheme that continuously updates a parametric background noise estimate during active phases, allowing immediate noise synthesis during inactive phases without the need for a warm-up phase, using spectral domain parameterization for realistic noise generation and improved signal separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the transmission of ordinary data stream encoding the recorded signal is stopped during inactive phases, then transmission bandwidth is reduced, but noise generation quality deteriorates due to lack of continuous noise update

Engineering Contradiction:

Improvetransmission bitrateVSAvoidnoise generation quality

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The background noise estimate is continuously updated during active phases in advance, so that when inactive phases occur, the decoder already has current noise parameters ready for immediate synthesis without requiring a warm-up phase. This preliminary updating during active periods enables quality noise generation to start immediately during inactive phases.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A parametric background noise estimate acts as an intermediary between the recorded signal during active phases and the synthesized noise during inactive phases. The encoder continuously updates this parametric estimate during active phases, and the decoder uses these parameters to generate realistic noise during inactive phases, maintaining quality without continuous transmission.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If a warm-up phase is used for noise synthesis during inactive phases, then noise generation quality improves, but transmission bitrate increases due to continued data stream transmission

Engineering Contradiction:

Improvenoise generation qualityVSAvoidtransmission bitrate

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The codec dynamically switches between encoding the full data stream during active phases and transmitting only parametric noise estimates during inactive phases. This dynamic adaptation allows the system to optimize bitrate in real-time based on signal activity while maintaining noise synthesis quality through continuous parameter updates.

Inventive Principle:

Principle #15Dynamics

3Loss of energy

If SID updates are transmitted only in regular intervals or when noise characteristics change, then transmission bitrate is reduced, but noise synthesis responsiveness deteriorates

Engineering Contradiction:

Improvetransmission bitrateVSAvoidnoise synthesis responsiveness

Core Design Contradiction:

Loss of energyVSSpeed

Solution Approach 1:

The background noise estimate is continuously updated during active phases without interruption, ensuring that the most current noise parameters are always available. This continuous updating maintains responsiveness to noise characteristic changes while optimizing bitrate by only transmitting updates when necessary during inactive phases.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system uses feedback from the detected signal activity to control when full data stream encoding occurs versus when parametric noise estimation suffices. During active phases, continuous encoding provides feedback updates; during inactive phases, the system relies on the continuously maintained parametric estimate, creating an efficient feedback-driven transmission strategy.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9153236B2Audio codec using noise synthesis during inactive phases

Publication Date: 2015.10.06 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

A parametric background noise estimate is continuously updated during an active or non-silence phase so that the noise generation may immediately be started with upon the entrance of an inactive phase following the active phase. In accordance with another aspect, a spectral domain is very efficiently used in order to parameterize the background noise thereby yielding a background noise synthesis which is more realistic and thus leads to a more transparent active to inactive phase switching.