Add binding to unmap NvBuSurface if it has been mapped

bindings/docstrings/pydocumentation.h

@@ -1541,6 +1541,12 @@ namespace pydsdoc
             :arg gst_buffer: address of the Gstbuffer which contains `NvBufSurface`
             :arg batchID: batch_id of the frame to be processed. This indicates the frame's index within `NvBufSurface`)pyds";
 
+        constexpr const char* unmap_nvds_buf_surface=R"pyds(
+            Unmap the previously mapped buffer. Do nothing if buffer has not been mapped.
+
+            :arg gst_buffer: address of the GstBuffer which contains `NvBufSurface`
+            :arg batch_id: batch_id of the frame to be unmap. This indicates the frame's index within `NvBufSurface`)pyds";
+
         constexpr const char* nvds_acquire_meta_lock=R"pyds(
             Acquire the lock before updating metadata.
 

bindings/src/bindfunctions.cpp

@@ -419,6 +419,34 @@ namespace pydeepstream {
               py::return_value_policy::reference,
               pydsdoc::methodsDoc::get_nvds_buf_surface);
 
+
+        /**
+         * Unmap the previously mapped buffer if it has been mapped.
+         * It's needed to prevent memory leaks.
+         * See https://forums.developer.nvidia.com/t/memory-leak-on-xavier-nx/234438 for details.
+         */
+        m.def("unmap_nvds_buf_surface",
+              [](size_t gst_buffer, int batch_id) {
+                  auto *buffer = reinterpret_cast<GstBuffer *>(gst_buffer);
+                  GstMapInfo map_info;
+                  gst_buffer_map(buffer, &map_info, GST_MAP_READ);
+                  auto *nvsurface = reinterpret_cast<NvBufSurface *>(map_info.data);
+                  gst_buffer_unmap(buffer, &map_info);
+
+                  // Unmap the buffer if it has been mapped
+                  if (nullptr != nvsurface->surfaceList[batch_id].mappedAddr.addr[0]) {
+                      int ret = NvBufSurfaceUnMap(nvsurface, batch_id, -1);
+                      if (ret < 0) {
+                          throw std::runtime_error(
+                              "unmap_nvds_buf_surface: Failed to unmap buffer");
+                      }
+                  }
+              },
+              "gst_buffer"_a,
+              "batch_id"_a,
+              pydsdoc::methodsDoc::unmap_nvds_buf_surface
+        );
+
         //FIXME: Find a better way of doing this
         /**
         * Type casting to @NvDsBatchMeta

docs/PYTHON_API/Methods/methodsdoc.rst

@@ -22,6 +22,12 @@ get_nvds_buf_surface
 
 .. autofunction:: pyds.get_nvds_buf_surface
 
+==============
+unmap_nvds_buf_surface
+==============
+
+.. autofunction:: pyds.unmap_nvds_buf_surface
+
 ==============
 nvds_acquire_meta_lock
 ==============