Research On The Fast Video Transcoding Algorithms Based On Multi-stage Decoding Information Reusing

Video transcoding techniques are mainly divided into two categories,homogeneous and heterogeneous,according to whether the source and destination standards are same or not during the transcoding.In heterogeneous transcoding,decoding information of the original standard,such as partition modes,reference pictures,motion vectors and intra prediction modes,will be used to accelerate the encoding process of target standards.How efficiently they will be utilized has a great effect on the coding performance of the transcoding.To efficiently utilize the decoding information in the transcoding process,a transcoding framework based on multi-stage decoding information reusing is proposed for fast video transcoding.In this framework,the decoding information is grouped into different layers and the reusing process is divided into different stages,in which decoding information in particular layer will be reused only when the corresponding information in the upper layer has been used in the previous stage.The proposed framework is implemented in two application scenarios,fast transcoding from H.264/AVC to HEVC and from HEVC to AVS2.The algorithm of H.264/AVC to HEVC fast transcoding is based on the previous work on an ultra-fast transcoder.A new early termination method substitutes the previous one and algorithms for 64x64 and AMP partitions are added into the transcoder.The proposed transcoder achieves up to 1.7x speedup and significant coding performance improvement over the previous one,and a 14x-20 x speedup with a 15%-19% loss over the HEVC reference software.The transcoding algorithm on HEVC to AVS2 transcoding achieves a similar speedup efficiency of a 11x-17 x speedup with a 9.6%-16.6% loss over the AVS2 reference software.