diff --git a/tests/common/streamtypebasicstest.cpp b/tests/common/streamtypebasicstest.cpp
index b852e1acd..9a25b4a1d 100644
--- a/tests/common/streamtypebasicstest.cpp
+++ b/tests/common/streamtypebasicstest.cpp
@@ -33,7 +33,7 @@ using std::cout;
 
 
 namespace lumiera {
-  namespace test {
+  namespace test_format {
     
     using control::STypeManager;
     
@@ -56,7 +56,7 @@ namespace lumiera {
           {
             STypeManager& typeManager = STypeManager::instance();
         
-            TODO ("set up a GAVL frame type");
+            gavl_video_format_t rawType = createRawType();
             TODO ("use this to retrieve an ImplFacade from the STypeManager");
             UNIMPLEMENTED ("at least preliminary implementation of the MediaImplLib interface for lib GAVL");
             TODO ("how to do a simple consistency check on the returned ImplFacade? can we re-create the GAVL frame type?");
@@ -75,7 +75,7 @@ namespace lumiera {
     LAUNCHER (StreamTypeBasics_test, "unit common");
     
     
-  } // namespace test
+  } // namespace test_format
     
 } // namespace lumiera
 
diff --git a/tests/common/streamtypelifecycletest.cpp b/tests/common/streamtypelifecycletest.cpp
index 82f7cf6b9..ce260da59 100644
--- a/tests/common/streamtypelifecycletest.cpp
+++ b/tests/common/streamtypelifecycletest.cpp
@@ -34,7 +34,7 @@ using std::cout;
 
 
 namespace lumiera {
-  namespace test {
+  namespace test_format {
     
     using mobject::Session;
     using control::STypeManager;
@@ -108,7 +108,7 @@ namespace lumiera {
     LAUNCHER (StreamTypeLifecycle_test, "unit common");
     
     
-  } // namespace test
+  } // namespace test_format
   
 } // namespace lumiera
 
diff --git a/tests/common/teststreamtypes.hpp b/tests/common/teststreamtypes.hpp
index 03409c7a9..e0d53f9e2 100644
--- a/tests/common/teststreamtypes.hpp
+++ b/tests/common/teststreamtypes.hpp
@@ -30,10 +30,49 @@
 #include "common/streamtype.hpp"
 #include "proc/control/stypemanager.hpp"
 
+extern "C" {
+#include <gavl/gavl.h>
+}
 
 
 namespace lumiera {
-  namespace test {
+  namespace test_format {
+  
+    namespace { // constants used to parametrize tests
+    
+      const int TEST_IMG_WIDTH = 40;
+      const int TEST_IMG_HEIGHT = 30;
+      
+      const int TEST_FRAME_DUR = GAVL_TIME_SCALE / 25; 
+    }
+    
+    /** Helper: create an raw GAVL type descriptor
+     *  usable for generating a Lumiera StreamType 
+     */
+    inline gavl_video_format_t
+    createRawType ()
+    {
+      gavl_video_format_t type;
+      
+      type.pixelformat = GAVL_RGB_24;
+      type.interlace_mode = GAVL_INTERLACE_NONE;
+      type.framerate_mode = GAVL_FRAMERATE_CONSTANT;
+      type.chroma_placement = GAVL_CHROMA_PLACEMENT_DEFAULT;
+      
+      type.image_width  = TEST_IMG_WIDTH;   // Width of the image in pixels
+      type.image_height = TEST_IMG_WIDTH;   // Height of the image in pixels
+      type.frame_width  = TEST_IMG_WIDTH;   // Width of the frame buffer in pixels, might be larger than image_width 
+      type.frame_height = TEST_IMG_WIDTH;   // Height of the frame buffer in pixels, might be larger than image_height
+  
+      type.pixel_width  = 1;              // Relative width of a pixel (pixel aspect ratio is pixel_width/pixel_height)
+      type.pixel_height = 1;             // Relative height of a pixel (pixel aspect ratio is pixel_width/pixel_height)
+
+      type.frame_duration = TEST_FRAME_DUR; // Duration of a frame in timescale tics. 
+      type.timescale = GAVL_TIME_SCALE;     // Timescale in tics per second  (is defined to be 1000000 as of 9/2008)
+      
+      return type;
+    }
+    
     
     /** Helper: create an implementation frame
      *  and build the corresponding streamtype
@@ -46,7 +85,7 @@ namespace lumiera {
     
     
     
-  } // namespace test
+  } // namespace test_format
 
 } // namespace lumiera
 #endif