Frame Type Selection for Off-line MPEG Encoding

摘要

Efficient MPEG encoding begins with the selection of each frame's coding type. Depending on the constraints of a given application, the options available for individual frame types differ. These options are further limited by the encoding environment, in particular the frame buffer size and computational power available. In this work we assume an off-line encoding environment, with its implicit unlimited frame buffer and arbitrarily fast computations. Such an environment enables us to examine ideal frame types for a variety of situations, with changing emphasis between encoded bits and motion estimation error. We find that the optimal frame types vary dramatically as focus shifts from bit allocation to motion estimation error, even for "natural" video sequences. When additional video effects such as fades and scene cuts are introduced, the frame types become even more interesting, deviating significantly from the M and N fixed-spacing scheme used by many real-time MPEG encoders.