Bit Rate Control Schemes for ROI Video Coding

Bit Rate control plays an important role in video coding. Region of Interest (ROI) based rate control has been attracting great attention due to the rapid demands in the region of interest in video coding. The main issue in video coding is the trade off between compression ratio and quality of the reconstructed signal. It is obvious that better quality can be achieved with smaller compression ratio and higher encoded stream bit rate. An optimal coder requires knowledge of the rate distortion (RD) model for the coding scheme. The R-D model is generally built in such a way that the quality of whole frames in a video sequence is taken into account. However in many applications like video monitoring and surveillance, telemedicine, videophone and videoconferencing, some areas in the consecutive frames of the video sequence are more important than others. It is desirable to encode those areas, called region of interest (ROI) with smaller distortion than the rest of the sequence (background). This paper presents a review of the available schemes for bit rate control in region of interest based video coding.