US Patent 7096245 Inverse discrete cosine transform supporting multiple decoding processes

The present invention provides an apparatus and method for providing a programmable inverse discrete cosine transform, wherein the transform coefficients are loaded into a memory area of a core transform device and a variety of coding standards can thereby be handled by the same programmable core device. The core device is configured to process a certain sized data block, and the incoming source blocks are converted to conform to this size. After transformation, the proper sized result can be extracted from the transform device output. A switchable speed-up mode provides for 4-point transforms, rather than 8-point transforms. Alternatively, the invention also provides for dedicated transform hardware to be switchably used in conjunction with programmable transform hardware, depending upon the type of coding being used, and the speed of inverse transform desired.