IETF RFC 5053 PDF

This document describes a Fully-Specified Forward Error Correction (FEC) scheme, corresponding to FEC Encoding ID 1, for the Raptor forward error correction code and its application to reliable delivery of data objects.

Raptor is a fountain code, i.e., as many encoding symbols as needed can be generated by the encoder on-the-fly from the source symbols of a source block of data. The decoder is able to recover the source block from any set of encoding symbols only slightly more in number than the number of source symbols.

The Raptor code described here is a systematic code, meaning that all the source symbols are among the encoding symbols that can be generated.