1. A method for transcoding regions of interest (ROI) in a video surveillance system that includes a camera with a high definition (HD) sensor for recording an observed scene in high resolution, a hierarchical encoder, a buffer for potential later ROI extraction and an extractor, the method comprising: extracting an image in moderate resolution from a hierarchical encoded datastream; extracting coefficients of higher resolution levels from said hierarchical encoded datastream; and adding the coefficients to an already decoded image, so that an image region of an ROI is of higher resolution and a hierarchical transcoding of spatial scalable regions of interest (ROI) is made; wherein the extractor extracts all packets, which contain image information in moderate resolution, from said hierarchical encoded datastream stored in the buffer and said extracted packets are decoded at a receiver and image data is displayed, wherein a user is able to request high frequency information of one or several interesting image regions, and wherein based on such a user request said extractor estimates all ROI packets containing high frequency information of the ROI, wherein non-ROI packets are all packets containing high frequency image information, wherein after classification the non-ROI packets are replaced by empty packets and wherein all empty packets and all ROI packets are transmitted and added to already transmitted packets of a lower resolution version of the image.