Quality aware MPEG-2 Stream Adaptation in Resource Constrained Systems

A number of algorithms have been presented for handling software decoding of MPEG-2 streams based on buffering or rate adjustment focusing on providing good average quality. The potentially arising drops in quality are tolerated, e.g., in transmissions over the Internet; they cannot be accepted in high quality consumer products: these mandate real-time methods. When resources, such as processing power or network bandwidth, are limited and not all frames can be handled, best effort decoders incur unnecessary quality decrease while wasting resources. In this paper, we present a method for quality aware frame selection for MPEG decoding under limited resources, based on realistic timing constraints for the decoding of MPEG streams. Given that not all frames can be processed, it selects those which will provide the best picture quality while matching the available resources, starting only such decoding, which is guaranteed to be completed. We formulate the method as real-time scheduling problem and present its application in an example scheduling algorithm. Results from study based on realistic MPEG-2 video underline the effectiveness of our approach.