Method for decoding mpeg compliant video bitstreams meeting 2-frame and letterboxing requirements

Abstract

A system and method for decoding an MPEG video bitstream comprising several macroblocks of data is disclosed. The system comprises a macroblock core (MBCORE) which processes video bitstream data and computes discrete cosine transform data corresponding to the processed video bitstream, and a parser which parses the video bitstream macroblocks into multiple data blocks used in subsequent stages of decoding. The system further includes a transformation/motion compensation core (TMCCORE) which is divided into multiple stages. The TMCCORE includes an IDCT first stage, an intermediate memory (transpose RAM), and an IDCT second stage. The IDCT first stage passes data to memory and the IDCT second stage receives data from memory. The IDCT first stage has the ability to operate on a first data block while the second stage simultaneously operates on a second data block. The TMCCORE receives the discrete cosine transform data from the MBCORE and calculates and reconstructs a frame therefrom using motion compensation. The MBCORE can operate on data from a first macroblock while the TMCCORE simultaneously operates on data from a second macroblock. The TMCCORE has the ability to reconstruct a picture from the inverse discrete cosine transformed data and motion data received from the reference subsystem. The TMCCORE reconstructs the picture from one macroblock while the inverse discrete cosine transform first and second stages simultaneously operate on data from the macroblock. Alternately, reconstruction may occur while second stage processing and MBCORE functions occur.