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.
['Tak-Piu Ip', 'Yui-Lam Chan', 'Chang-Hong Fu', 'Wan-Chi Siu']
Macroblock-based algorithm for dual-bitstream MPEG video streaming with VCR functionalities