Forward Error Correction Header Signaling for Real-Time Media
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Solution Overview
Problem
Current FEC methods, such as SMPTE 2002-1, are insufficient for real-time audio and video transmission over IP networks as they do not adequately support more powerful error correction codes like Reed-Solomon (N, K) for burst loss recovery, and lack sufficient signaling for FEC block size information, limiting their ability to correct multiple packet losses.
Innovation Solution
A new signaling method and syntax for FEC headers are introduced, including fields for total packet count and FEC block size, allowing for the use of more powerful FEC codes like Reed-Solomon (N, K) to generate and transmit FEC packets, and enabling recovery of multiple lost packets by including FEC-related control information in the header.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If SMPTE 2002-1 FEC method is used, then implementation is simple with XOR encoding, but error correction capability is limited to single packet loss
Solution Approach 1:
The patent changes the FEC coding parameters from simple XOR (N=K+1) to Reed-Solomon (N, K) codes where N can be independently configured. This allows flexible adjustment of error correction capability by selecting different block sizes N and protection levels, enabling recovery from multiple packet losses while maintaining implementation feasibility through standardized RS code implementations.
2Reliability
If Reed-Solomon (N, K) codes are used, then error correction capability increases for multiple packet losses, but signaling complexity increases due to additional block size information
Solution Approach 1:
The patent performs preliminary action by embedding the total block size N in the FEC header of each transmitted FEC packet. This pre-signaling of block size information allows the receiver to correctly configure the decoding process before actual packet loss recovery is needed, eliminating the need for complex dynamic negotiation and simplifying the overall signaling requirement.
3Quantity of substance
If FEC block size is not included in header, then header size is reduced, but receiver cannot correctly decode without knowing total packets N
Solution Approach 1:
The patent performs preliminary action by including the total block size N in the FEC header. This pre-provides the receiver with all necessary decoding parameters (block size N, protected packets K, code type) before the actual decoding operation, enabling correct recovery of lost packets without requiring additional signaling or complex inference mechanisms.
Data Source
AI summary
A method and apparatus are described for protecting real time media including receiving media packets, generating media bit strings from the media packets, applying a forward error correcting code across the generated media bit strings to generate at least one forward error correcting bit string and generating at least one forward error correcting packet from the at least one forward error correcting bit string. Also described are a method and apparatus for recovering from losses of real time media packets including forming media bit strings from received media packets, forming forward error correcting bit strings from received forward error correcting packets, decoding the formed media bit strings and forward error correcting bit strings to obtain recovered media bit strings and recover lost media packets from the recovered media bit strings. Further described is a data structure for a forward error correcting header on computer readable media.