diff --git a/openbr/plugins/stream.cpp b/openbr/plugins/stream.cpp
index 573169a..22ee4d8 100644
--- a/openbr/plugins/stream.cpp
+++ b/openbr/plugins/stream.cpp
@@ -1027,14 +1027,46 @@ public:
 
     void train(const TemplateList & data)
     {
+        (void) data;
+        qFatal("terminal train called on interior node.");
+    }
+
+    void subProject(QList<TemplateList> & data, int end_idx)
+    {
+        if (end_idx == 0)
+            return;
+
+        // Set transforms to the start, up to end_idx
+        QList<Transform *> backup = this->transforms;
+        transforms = backup.mid(0,end_idx);
+
+        // Reinitialize, we now act as a shorter stream.
+        init();
+
+        for (int i=0; i < data.size(); i++) {
+            projectUpdate(data[i], data[i]);
+        }
+        transforms = backup;
+    }
+
+    void train(const QList<TemplateList> & data)
+    {
         if (!trainable) {
             qWarning("Attempted to train untrainable transform, nothing will happen.");
             return;
         }
-        qFatal("Stream train is currently not implemented.");
-        foreach(Transform * transform, transforms) {
-            transform->train(data);
+
+        for (int i=0; i < transforms.size(); i++) {
+            // OK we have a trainable transform, we need to get input data for it.
+            if (transforms[i]->trainable) {
+                QList<TemplateList> copy = data;
+                // Project from the start to the trainable stage.
+                subProject(copy,i);
+                transforms[i]->train(copy);
+            }
         }
+        // Re-initialize because subProject probably messed us up.
+        init();
     }
 
     bool timeVarying() const { return true; }
@@ -1285,6 +1317,12 @@ public:
 
     void train(const TemplateList & data)
     {
+        (void) data;
+        qFatal("terminal train called on interior node.");
+    }
+
+    void train(const QList<TemplateList> & data)
+    {
         basis.train(data);
     }