Reducing computational complexity of three-dimensional discrete cosine transform in video coding process

摘要

Low complexity video coding schemes are aimed to provide video encoding services also for devices with restricted computational power. Video coding process based on the three-dimensional discrete cosine transform (3D DCT) can offer a low complexity video encoder by omitting the computationally demanding motion estimation operation. In this coding scheme, extended fast transform is also used, instead of the motion estimation, to decorrelate the temporal dimension of video data. Typically, the most complex part of the 3D DCT based coding process is the three-dimensional transform. In this paper, we demonstrate methods that can be used in lossy coding process to reduce the number of one-dimensional transforms required to complete the full 3D DCT or its inverse operation. Because unnecessary computations can be omitted, fewer operations are required to complete the transform. Results include the obtained computational savings for standard video test sequences. The savings are reported in terms of computational operations. Generally, the reduced number of computational operations also implies longer battery lifetime for portable devices.