Compression by indexing: an improvement over MPEG-4 body animation parameter compression

摘要

Body Animation Parameters (BAPs) are used to animate MPEG-4 compliant virtual human-like characters. In order to stream BAPs in real time interactive environments, the BAPs are compressed for low bitrate representation using a standard MPEG-4 compression pipeline. However, the standard MPEG-4 compression is inefficient for streaming to power-constrained devices, since the streamed data requires extra power in terms of CPU cycles for decompression. In this paper, we have proposed and implemented an indexing technique for a BAP data stream, resulting in a compressed representation of the motion data. The resulting compressed representation of the BAPs is 'superior to the MPEG-4-based BAP compression in terms of both, required network throughput and power consumption at the client end to receive the compressed data stream and extract the original BAP data from the compressed representation. Although the resulting motion after de-compression at the client end is lossy, the motion distortion is minimized by intelligent use of the hierarchical structure of the skeletal avatar model. Consequently, the proposed indexing method is ideal for streaming of motion data to power- and network- constrained devices such as PDAs, Pocket PCs and Laptop PCs operating in battery mode and other devices in a mobile network environment.