The flexcode source-channel coding approach for audio and speech transmission

The FlexCode project is a joint research project of KTH Stockholm, RWTH Aachen University, Ericsson AB, Nokia, and Orange/France Telecom under the umbrella of the sixth framework programme of the European Commission (http://www.flexcode.eu). In this paper we present the generic channel coding platform developed within the FlexCode project. This channel encoder provides iterative source-channel decoding at the receiver in order to achieve near-capacity transmission of the source coder parameters. The structure of the encoder allows to flexibly adapt instantaneously the source and channel coding rates according to varying conditions. The approach handles both main operating modes of the FlexCode project: constrained resolution scalar quantization and constrained entropy scalar quantization which lead to either constant or variable bit rates.