Hybrid coding with pre-buffering and pre-analysis in a software-based codec environment

摘要

A concept for a software oriented video telephone codec compatible to CCITT draft recommendation H.261 is presented. An overview is given of the hybrid DPCM/transform coding which has been adopted for video telephone applications in digital networks at 64 kbit/s up to 2.048 Mbit/s data rate. The principle of an effective coding procedure is described leading to minimized and optimally distributed processing power while allowing high picture quality and minimum delay in order to retain interactivity of the video telephone service. The paper is focused on the coding strategy which is based on a pre-analysis of the input pictures in terms of change detection and structure analysis. Thus the processing power available can be efficiently utilized to get a constant picture quality at low hardware expense.