Frédéric Devreese (b. 1929) is a prominent Belgian classical and film composer who has written over 200 musical compositions, including 22 film scores. In this paper, we approach the analysis of four of his compositions, including one film score cue, by examining the presence and absence of silence. The chosen pieces were personally recommended and selected by the composer himself, as being relevant for their usage of silence. Our subject of study is primarily focused on silences that are represented in the score (i.e. rests, phrase marks, staccati, breath marks, etc.). However, a brief comparison with two selected recordings for each score will be made, as part of a comparative analysis. Two new musicological tools are presented and tested in this study, namely: Barcode of Synchronized Rests (BSR), and Barcode of the Silent Waveform (BSW). Consequently, a better understanding of the analysed compositions is achieved, and an analytical method for studying functions of silence is suggested, opening horizons to future silence-based musicological studies.