An Efficient Motion Estimation Method for H.264-Based Video Transcoding with Spatial Resolution Conversion

Motivated by the wide adoption of H.264 and the demand of universal multimedia data access over the expanding network with diverse devices, this paper studies H.264-based video transcoding with spatial resolution conversion. First, a practical solution for efficiently determining a reference frame is proposed to take advantage of the new feature of multiple references in H.264. Then, a motion vector estimation algorithm based on a multiple linear regression model is proposed to utilize the motion information in the original scenes for efficiently predicting motion vectors in the down-scaled scene. Experimental results show that, compared with a benchmark solution, the proposed method significantly reduces the transcoding complexity by 16 times while maintaining comparable rate distortion performance with a decrease of 0.06 dB in PSNR and 4% increase in the bit rate.