Transcoding based robust streaming of compressed video

A variety of techniques have been proposed to enhance the error robustness of the video streaming system. However, most of them improves the error resilience during compression rather than after compression. In this paper, we propose a novel transcoding based scheme called lossless inter frame transcoding (LIFT) scheme to improve the error resilience of existing compressed video stream. In the LIFT scheme, inter coded blocks are selectively transcoded into new kind of blocks called 'L-block'. At the decoder, the L-block can be transcoded back to the original P-block when the prediction is available and can also be robustly decoded as I-block when the prediction is unavailable. By offline transcoding and online adjusting the ratio of P-blocks and L-blocks, the proposed streaming server achieves error robustness scalability. Experimental results demonstrate the correctness and effectiveness of the proposed method.