Predictive Audio Codec Block Segmentation for Packet Loss
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Solution Overview
Problem
Predictive coding methods for real-time signal transmission over packet switched networks face challenges with error propagation due to lost packets and difficulty in encoding sudden signal transitions, leading to degraded signal quality.
Innovation Solution
The method involves dividing a signal into blocks and encoding/decoding each block independently, using a start state encoded/decoded between block boundaries, with the second and third block parts encoded/decoded in opposite directions to maintain predictive coding while avoiding error propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If predictive coding is used for bandwidth efficient transmission, then bandwidth usage is reduced, but error propagation occurs when packets are lost
Solution Approach 1:
The patent divides the encoded signal into discrete packets, each containing an encoded signal portion and associated coder state information. This segmentation allows each packet to be independently decoded without requiring continuous state information from previous packets, thereby preventing error propagation while maintaining predictive coding efficiency.
2Reliability
If coder state is reset at the beginning of each packet to prevent error propagation, then error propagation is reduced, but signal quality degradation occurs
Solution Approach 1:
The patent includes the coder state information within each packet before transmission, so that the decoder has the necessary state information already available when the packet arrives. This preliminary inclusion of state information eliminates the need for reset operations while maintaining continuous predictive coding accuracy.
3Reliability
If different redundancy schemes are used to approximate coder state after lost packets, then error propagation is reduced, but bandwidth increases and error propagation is not completely eliminated
Solution Approach 1:
The patent uses coder state information as an intermediary element that is transmitted within each packet. This state information acts as a mediator that enables the decoder to reconstruct the predictive coding context without requiring additional redundancy schemes or increased bandwidth for error protection.
4Device complexity
If conventional predictive coding is used for sudden signal transitions, then encoding is simple, but signal quality is degraded at transitions
Solution Approach 1:
The patent dynamically adjusts the coder state information included in each packet based on the signal characteristics. For sudden transitions, the system includes more recent state information to capture the transition accurately, while for steady-state signals, it uses standard predictive coding. This dynamic adaptation maintains signal quality without significantly increasing encoding complexity.
Data Source
AI summary
The present invention relates to improvements of predictive encoding/decoding operations performed on a signal which is transmitted over a packet switched network. The signal is encoded on a block by block basis in such way that a block A-B is predictive encoded independently of any preceding blocks. A start state (715) located somewhere between the end boundaries A and B of the block is encoded using any applicable coding method. Both block parts surrounding the start state is then predictive encoded based on the start state and in opposite directions with respect to each other, thereby resulting in a full encoded representation (745) of the block A-B. At the decoding end, corresponding decoding operations are performed.