Fast video transcoding from HEVC to VP9

HEVC and VP9 are the current state-of-the-art in video compression, since their bit-streams were recently finalized in January and May 2013, respectively. These codecs are the generational successors of the currently most widely-used video codecs, H.264/AVC and VP8, respectively. Consequently, it is expected that in the near future these new codecs will replace their predecessors. However, the process of converting video contents compressed with one standard to those using another standard is highly computationally expensive, since a priori the video contents must be decompressed and compressed with the target video encoder. Nevertheless, it is known that some information can be extracted from the decoding process in order to accelerate the encoding process. In this paper, some techniques for transcoding from HEVC to VP9 are presented. By using some information extracted from the HEVC decoding process some coding modes will be discarded from being checked in the VP9 encoder. By applying the proposed approaches, a reduction of about 60% of the coding complexity is achieved with acceptable Rate Distortion penalties.