diff --git a/plugins/preprocess/preprocess_node.cpp b/plugins/preprocess/preprocess_node.cpp
index 889b665..e3ff5ef 100644
--- a/plugins/preprocess/preprocess_node.cpp
+++ b/plugins/preprocess/preprocess_node.cpp
@@ -302,13 +302,27 @@ private:
             return;
         }
 
-        size_t out_size = CalcImageSizeStrided(dst_wstride, dst_hstride, out_fmt);
-        if (out_size == 0 || src_fmt_rga == RK_FORMAT_UNKNOWN || dst_fmt_rga == RK_FORMAT_UNKNOWN) {
+        // Calculate proper strides (RGA requires aligned strides)
+        // For YUV formats, wstride is the width of Y plane
+        // For RGB/BGR formats, wstride is width (not width*3)
+        int src_wstride = Align16(frame->width);
+        int src_hstride = Align16(frame->height);
+        int dst_wstride = Align16(out_w);
+        int dst_hstride = Align16(out_h);
+
+        if (src_fmt_rga == RK_FORMAT_UNKNOWN || dst_fmt_rga == RK_FORMAT_UNKNOWN) {
             std::cerr << "[preprocess] unsupported format for RGA\n";
             PushToDownstream(frame);
             return;
         }
 
+        size_t out_size = CalcImageSizeStrided(dst_wstride, dst_hstride, out_fmt);
+        if (out_size == 0) {
+            std::cerr << "[preprocess] invalid output size for RGA\n";
+            PushToDownstream(frame);
+            return;
+        }
+
         // Use DMA-BUF allocation to avoid >4GB address issue with RGA
         auto dma_buf = DmaAlloc(out_size);
         if (!dma_buf || !dma_buf->valid()) {
@@ -317,14 +331,6 @@ private:
             return;
         }
 
-        // Calculate proper strides (RGA requires aligned strides)
-        // For YUV formats, wstride is the width of Y plane
-        // For RGB/BGR formats, wstride is width (not width*3)
-        int src_wstride = Align16(frame->width);
-        int src_hstride = Align16(frame->height);
-        int dst_wstride = Align16(out_w);
-        int dst_hstride = Align16(out_h);
-
         if (processed_ < 3) {
             std::cout << "[preprocess] src: " << frame->width << "x" << frame->height
                       << " fmt=" << static_cast<int>(frame->format) << " rga_fmt=" << src_fmt_rga