Hybrid Bit-stream Rewriting from Scalable Video Coding to H.264/AVC

Scalable Video Coding (SVC) is an extension of H.264/AVC standard. The base layer of SVC is compatible with H.264/AVC standard, while the enhancement layers provide desired temporal, quality and/or spatial scalabilities. Bit-stream rewriting in SVC standard allows an SVC bit-stream to be converted to an H.264/AVC bit-stream without quality loss and preferably with low computational complexity. However, current rewriting is only supported in quality scalability rather than spatial scalability, which limits the application in many practical scenarios. In this paper, a hybrid bit-stream rewriting approach to support both quality and spatial scalability is proposed based on the principle of residue upsampling in transform domain. The computational complexity of the proposed approach is much lower than the conventional scheme of cascading transcoding. Extensive experimental results demonstrate that the loss of the rate-distortion (RD) performance of the proposed rewritable SVC bit-stream is acceptable compared with the conventional SVC bit-stream, however, the RD performance is better than that of simulcast. Furthermore, the RD performance of the H.264/AVC bit-stream rewritten from the rewritable SVC bit-stream is even better than that of the input SVC bit-stream. Compared with the cascading transcoding scheme, the proposed hybrid rewriting can achieve 0.8 dB Y-PSNR gains while saving 80% processing time on average.