A New MERIT Version for MPEG-2 Encoded Files

Abstract : The MPEG Encoded Retrieval and Indexation Toolkit (MERIT) performs video segmentation of MPEG files in the compressed domain, using an algorithm based on macroblock type statistics. It was written in C by V. Kobla in 1995 for his doctoral work at the University of Maryland. Kobla's code dealt with MPEG-1 files only. In this report, we update MERIT to analyze MPEG-2 files as well. We modify the file parsing process to account for the MPEG-2 specifications. We account for the new motion compensation modes introduced by MPEG-2 specifications. We account for the new motion compensation modes introduced by MPEG-2 in preliminary computations, generating data structures that allow the original MERIT segmentation algorithm to work properly. A series of tests confirmed the validity of our solutions. The new version 4.0 of MERIT is a superset of MERIT 3.3, insofar as it gives the same results for MPEG-1 files, and is able to analyze MPEG-2 files using almost all the available options. Further improvements could be made to address key-frame storage and higher chrominance formats.