The latest High Efficiency Video Coding (HEVC) standard achieves significant compression efficiency improvement over the H.264 standard, at a much higher cost of computational complexity. A framework for software-based H.264 to HEVC transcoding on multicore processors and distributed systems is provided. By utilizing information extracted from the input H.264 bitstream, the transcoding process can be accelerated at a high ratio with modest visual quality loss. Wavefront Parallel Processing (WPP) and SIMD acceleration are also implemented to improve the trans coding efficiency on multi-core processors with SIMD instruction set extensions. Based on the HEVC HM 12.0 reference software and using standard HEVC test bitstreams, the proposed transcoder can achieve around 120× speed up over decoding and re-encoding based on ffmpeg and the HM software without significant R-D performance loss.