Region-of-interest based compressed domain video transcoding scheme

We propose a fast video transcoding technique based on region-of-interest (ROI) determination. The ROIs are identified using the properties of the human visual system (HVS), applied in the compressed domain. We use the edge, motion and spatial frequency content of the video frame as the parameters in identifying perceptually important regions in the compressed domain (Agarwal, G. et al., 2003). The TM5 rate-control of the video transcoder is modified to assign relatively more bits to the ROIs, thereby providing better quality to the areas that are likely to attract the viewer´s attention. The ROI determination in the compressed domain has been modified to give more robust results. Our algorithm achieves a speed-up of 15-20 times as compared to similar algorithms in the pixel domain, while giving comparable results. This computation is only around 8% of the total transcoder complexity.