A low complexity H.261-compatible software video decoder

摘要

The design of a video decoder suitable for implementation in software is considered, in the context of a desktop videoconferencing system. It is required that the decoder handle bit streams from standard H.261 encoders, in order to facilitate interworking with existing systems. Real-time operation in software is achieved by decoding only the low-frequency components in the bit stream, and producing a decimated image. The problem of minimising the drift incurred in this approach is analysed and solved, and an expression for the mean squared drift error is given. The accuracy of the formulation is confirmed by experiment. In addition, several drift-reducing filters are designed and evaluated.