Andrey Semashev contributed to the FFmpeg/FFmpeg repository by addressing a critical regression in the librsvg decoder, focusing on restoring build compatibility across multiple librsvg versions. He implemented a version-aware approach in C, conditionally defining viewport width and height to resolve the 'viewport undeclared' compilation error encountered with librsvg 2.50.3 and earlier releases. This fix ensures that the decoder remains functional with both older and newer versions of librsvg, reducing build failures for users. Andrey’s work demonstrated a strong understanding of C programming and FFmpeg internals, delivering a targeted solution that improved cross-version reliability without introducing new regressions.