How does the TM work?
Rate control and adaptive quantization are divided into three steps: Step One: Target Bit Allocation In Complexity Estimation, the global complexity measures assign relative weights to each picture type (I,P,B). These weights (Xi, Xp, Xb) are reflected by the typical coded frame size of I, P, and B pictures (see typical frame size discussion). I pictures are usually assigned the largest weight since they have the greatest stability factor in an image sequence and contain the most “new information” in a sequence. B pictures are assigned the smallest weight since B energy do not propagate into other pictures and are usually more highly correlated with neighboring P and I pictures than P pictures are. The bit target for a frame is based on the frame type, the remaining number of bits left in the Group of Pictures (GOP) allocation, and the immediate statistical history of previously coded pictures (sort of a “moving average” global rate control, if you will). Step Two: Rate Control via Buf
