diff --git a/plugins/CMakeLists.txt b/plugins/CMakeLists.txt
index 5c363e2..3fd3b95 100644
--- a/plugins/CMakeLists.txt
+++ b/plugins/CMakeLists.txt
@@ -188,6 +188,12 @@ if(RK3588_ENABLE_FFMPEG)
     target_compile_definitions(preprocess PRIVATE RK3588_ENABLE_FFMPEG)
     target_include_directories(preprocess PRIVATE ${FFMPEG_INCLUDE_DIRS})
     target_link_libraries(preprocess PRIVATE PkgConfig::FFMPEG)
+
+    # swscale is required when preprocess runs in software mode (use_rga=false)
+    pkg_check_modules(SWSCALE_PREPROCESS IMPORTED_TARGET libswscale)
+    if(SWSCALE_PREPROCESS_FOUND)
+        target_link_libraries(preprocess PRIVATE PkgConfig::SWSCALE_PREPROCESS)
+    endif()
 endif()
 if(RK3588_ENABLE_RGA AND RK_RGA_LIB)
     target_compile_definitions(preprocess PRIVATE RK3588_ENABLE_RGA)