Architectures for MPEG compressed bitstream scaling

The idea of moving picture expert group (MPEG) bitstream scaling relates to altering or scaling the amount of data in a previously compressed MPEG bitstream. The new scaled bitstream conforms to constraints that are not known nor considered when the original preceded bitstream was constructed. Numerous applications for video transmission and storage are being developed based on the MPEG video coding standard. Applications such as video on demand, trick-play track on digital video tape recorders (VTR´s) and extended-play recording on VTR´s motivate the idea of bitstream scaling. In this paper, we present several bitstream scaling methods for the purpose of reducing the rate of constant bit rate (CBR) encoded bitstreams. The different methods have varying hardware implementation complexity and associated trade-offs in resulting image quality. Simulation results on MPEG test sequences demonstrate the typical performance trade-offs of the methods