Memory conscious 3D wavelet transform

The video compression algorithms based on the 3D wavelet transform obtain excellent compression rates at the expense of huge memory requirements, which drastically affect the execution time of such applications. The goal of this work is to mitigate the memory problem by exploiting the memory hierarchy of the processor through blocking. In particular, we present two blocking approaches: cube and rectangular that differ in the way that the original working set is divided. We also propose the reuse of previous computations in order to decrease the number of memory accesses and floating point operations. Results show that the rectangular overlapped approach with computation reuse obtains the best results in terms of execution time, a speedup of 2.42 over the non-blocking non-overlapped wavelet transform, maintaining the compression ratio and the video quality (PSNR) of the original encoder based on the 3D wavelet transform.