Spatial transcoding from Scalable Video Coding to H.264/AVC

Scalable Video Coding (SVC) is backwards compatible to H.264/AVC in the sense that the base layer sub-bitstream is decodable by an H.264/AVC decoder. However, there are applications wherein it is desirable for an H.264/AVC decoder to obtain a higher resolution video representation than the base layer within SVC. In order to fulfill the needs of such application scenarios, transcoding of SVC enhancement layers to H.264/AVC is required. This paper presents a transcoding scheme that is capable of transcoding a spatial scalable SVC bitstreams to H.264/AVC bitstreams that provide high resolution than the H.264/AVC compliant base layer. To reduce the complexity at the transcoder, a fast mode decision (MD) process is proposed, wherein the original SVC macroblock coding modes and motion information are reused as much as possible. Experimental results show that proposed scheme performs elegantly compared with full-decoding-and-encoding transcoding with low computational complexity.