Motion-assisted rate control for ME/MC-based codecs [video coding]

We propose motion-assisted rate control (MARC), a scheme that utilizes local statistics of motion vectors and motion-compensated error signals. Since human perception on macroblocks with motion is different from that on macroblocks that belong to static part of a frame, the usage of motion statistics can potentially provide useful information regarding how to distribute effectively the available bit budget. A sensitivity value is calculated out of local motion information and complementary texture information for each macroblock in a frame and this value is used to compose a sensitivity map for each frame. MARC utilizes this map for bit assignment in rate control. Since a motion estimation/compensation (ME/MC)-based video codec already generates the motion and texture information required, the calculation overhead is minimal. Although MPEG-2 is used in our experiments, MARC has potential to be adopted in any ME/MC video codec with little effort. Since it only enhances the encoding procedure, compatibility with standard codecs is preserved. Although it is designed to enhance the subjective quality of moving/interesting objects within a frame, through our experiments it is found that the objective quality (PSNR) is also improved.