Adaptive coding schemes for support of multicast audio to wireless devices

The mobile wireless environment, characterized by dynamically varying bandwidth and signal quality, provides a harsh environment for audio and video applications. Insufficient bandwidth leads to losses and delays which significantly reduce the quality of playback at the receiver. Such an environment demands application support for bandwidth adaptation. Audio applications in particular have traditionally operated at fixed rates and are prime candidates for enhancement. We propose a DCT-based audio decomposition (DAD) scheme for real-time general audio streams in the multicast environment which allows audio quality to be traded off against reductions in bandwidth usage. We compare the performance of DAD, using objective and subjective measures, against two other schemes which also support adaptation to restricted bandwidth.