diff --git a/plugins/publish/publish_node.cpp b/plugins/publish/publish_node.cpp
index 57a7efc..1bee911 100644
--- a/plugins/publish/publish_node.cpp
+++ b/plugins/publish/publish_node.cpp
@@ -405,7 +405,28 @@ public:
             auto* pos = static_cast<uint8_t*>(mpp_packet_get_pos(packet));
             size_t len = mpp_packet_get_length(packet);
             out.data.assign(pos, pos + len);
-            out.key = (mpp_packet_get_flag(packet) & 0x10) != 0;  // INTRA flag
+            // MPP_PACKET_FLAG_INTRA = 0x08, also check NAL type for H264 IDR (type 5)
+            RK_U32 flag = mpp_packet_get_flag(packet);
+            out.key = (flag & 0x08) != 0;  // MPP_PACKET_FLAG_INTRA
+            // Fallback: check H264 NAL unit type if MPP flag not set
+            if (!out.key && len >= 5) {
+                // Find NAL start code and check type
+                for (size_t i = 0; i + 4 < len; ++i) {
+                    if (pos[i] == 0 && pos[i+1] == 0 && pos[i+2] == 0 && pos[i+3] == 1) {
+                        uint8_t nal_type = pos[i+4] & 0x1F;
+                        if (nal_type == 5 || nal_type == 7) {  // IDR or SPS
+                            out.key = true;
+                            break;
+                        }
+                    } else if (pos[i] == 0 && pos[i+1] == 0 && pos[i+2] == 1) {
+                        uint8_t nal_type = pos[i+3] & 0x1F;
+                        if (nal_type == 5 || nal_type == 7) {
+                            out.key = true;
+                            break;
+                        }
+                    }
+                }
+            }
             int64_t mpp_pts = mpp_packet_get_pts(packet);
             // Use encoder's pts if valid, otherwise compute from frame count
             out.pts_ms = mpp_pts > 0 ? mpp_pts : static_cast<int64_t>(frame_count_ * 1000 / fps_);