Macroblock-based algorithm for dual-bitstream MPEG video streaming with VCR functionalities

Reverse playback is the most common video cassette recording (VCR) function in many digital video players. However, the predictive processing techniques employed in MPEG severely complicate reverse-play operation. One approach to achieve reverse playback is to store an additional backward-encoded bitstream on the server. Once the client requests a backward-play operation, the server selects an appropriate frame for the client from either the forward or backward-encoded bitstream by considering the cost of network bandwidth and the decoder complexity. Unfortunately, the forward- and backward-encoded bitstreams are encoded separately. The frame that was previously decoded. by the client may not be exactly identical to the reference of the current selected frame and a drift problem occurs. We propose a macroblock-based approach to alleviate the drift problem with minimal requirements on the network bandwidth and the decoder complexity. Novel macroblock-based techniques are used to manipulate the necessary macroblocks in the compressed-domain and the server then sends the processed macroblocks to the client machine. Experimental results show that, as compared to the conventional dual-bitstream system, the new streaming system enhances the quality of the reconstructed frame significantly.