Audio Frame Packetization with Segment Headers for Error Recovery

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Solution Overview

Problem

Transmission of compressed audio data over error-prone channels with fixed length data segments leads to significant losses and audible issues due to variable frame lengths, where a single bit error can cause entire frames to be discarded, resulting in time shifts and dropouts.

Innovation Solution

The method involves mapping compressed audio frames of arbitrary size into fixed-size data segments with a transport protocol header that identifies frame boundaries and interpretable data entities, allowing for efficient error management and partial concealment by making each segment self-contained and enabling correct time synchronization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If variable length audio frames are transmitted over fixed length data segments, then the audio coding efficiency is improved, but the reliability of transmission deteriorates due to error propagation

Engineering Contradiction:
Improveaudio coding efficiencyVSAvoidtransmission reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent divides the transmission data into fixed length segments, each containing a complete audio frame or a portion thereof. Each segment is independently transmitted and can be independently decoded, preventing error propagation across frame boundaries. The segmentation allows the system to maintain fixed length transmission units while preserving the variable length nature of audio frames for coding efficiency.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent inserts synchronization information and frame boundary markers at predetermined positions within the fixed length segments before transmission. This preliminary action enables the receiver to quickly identify frame boundaries and resynchronize after errors without discarding entire frames, thereby improving transmission reliability while maintaining coding efficiency.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If error correction is applied to protect against transmission errors, then the reliability is improved, but the data rate decreases due to overhead

Engineering Contradiction:
Improveerror protectionVSAvoiddata rate
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies error protection selectively rather than uniformly across all data. By identifying critical regions such as frame boundaries and synchronization information, the system applies stronger error protection only where necessary, while using lighter or no protection for less critical data portions. This partial action maintains reliability for essential information while minimizing overall overhead and preserving data rate.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent implements differential error protection where different portions of the data stream receive different levels of error correction. Critical synchronization and boundary information receives robust protection, while spectral data and less critical information receive minimal or no error correction. This local quality approach optimizes the balance between reliability and data rate by matching protection levels to the actual importance of each data region.

Inventive Principle:
Principle #3Local quality

3Reliability

If a single bit error occurs in entropy coded data, then the transmission reliability is maintained, but the decoding accuracy deteriorates due to frame discard

Engineering Contradiction:
Improvetransmission integrityVSAvoiddecoding accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent extracts and separates critical frame boundary information and synchronization data from the main entropy coded data stream. By placing these critical elements in distinct, protected regions with clear delimiters, the system can identify and isolate errors without requiring discard of entire frames. This extraction allows selective reconstruction of corrupted portions while preserving the majority of valid data.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces intermediate synchronization markers and frame boundary indicators that act as mediators between the transmitted data and the decoder. These intermediaries provide reference points that allow the decoder to detect errors, locate frame boundaries, and resynchronize without discarding entire frames. The intermediaries enable graceful degradation where partial frame data can be utilized even when errors occur.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP1961181B1Apparatus for generating and interpreting a data stream having a series of segments using data in subsequent data frames
Publication Date: 2009.04.15 DOLBY SWEDEN AB
  • EP1961181B1 patent drawingFigure 1~2a
  • EP1961181B1 patent drawingFigure 2b~3b
  • EP1961181B1 patent drawingFigure 3c~4

AI summary

An apparatus for generating a data stream having a series of segments using data organized in subsequent data frames, a data frame having more important and less important data. It comprises a packetiser for packetising data from a data frame into the series of segments having a first segment and a second segment, where the packetiser is operative to packetise the data of the frame so that a starting point of the more important data coincides with a starting point of the first segment and an information block adder for adding a first information block to the first segment.