diff --git a/src/mynteye/api/processor.cc b/src/mynteye/api/processor.cc
index 2583b5a..8d65b35 100644
--- a/src/mynteye/api/processor.cc
+++ b/src/mynteye/api/processor.cc
@@ -52,7 +52,7 @@ std::string Processor::Name() {
 }
 
 void Processor::AddChild(const std::shared_ptr<Processor> &child) {
-  child->parent_ = this;
+  child->parent_ = shared_from_this();
   childs_.push_back(child);
 }
 
@@ -81,7 +81,8 @@ void Processor::Activate(bool parents) {
     return;
   if (parents) {
     // Activate all parents
-    Processor *parent = parent_;
+    auto parent = parent_;
+    // Processor *parent = parent_;
     while (parent != nullptr) {
       parent->Activate();
       parent = parent->parent_;
@@ -97,7 +98,8 @@ void Processor::Deactivate(bool childs) {
     return;
   if (childs) {
     // Deactivate all childs
-    iterate_processors(GetChilds(), [](std::shared_ptr<Processor> proc) {
+    iterate_processors_PtoC_after(GetChilds(),
+        [](std::shared_ptr<Processor> proc) {
       proc->Deactivate();
     });
   }
@@ -152,6 +154,10 @@ std::uint64_t Processor::GetDroppedCount() {
   return dropped_count_;
 }
 
+std::shared_ptr<Processor> Processor::GetParent() {
+  return parent_;
+}
+
 void Processor::Run() {
   VLOG(2) << Name() << " thread start";
 
diff --git a/src/mynteye/api/processor.h b/src/mynteye/api/processor.h
index 11fa6f7..df5d42d 100644
--- a/src/mynteye/api/processor.h
+++ b/src/mynteye/api/processor.h
@@ -23,18 +23,22 @@
 #include <mutex>
 #include <string>
 #include <thread>
+#include <vector>
+// #include "mynteye/api/synthetic.h"
 
 #include "mynteye/mynteye.h"
 #include "mynteye/api/object.h"
 
 MYNTEYE_BEGIN_NAMESPACE
 
-class Processor /*: public std::enable_shared_from_this<Processor>*/ {
+class Processor :
+    public std::enable_shared_from_this<Processor> {
  public:
   using PreProcessCallback = std::function<void(Object *const)>;
   using PostProcessCallback = std::function<void(Object *const)>;
   using ProcessCallback = std::function<bool(
-      Object *const in, Object *const out, Processor *const parent)>;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent)>;
 
   explicit Processor(std::int32_t proc_period = 0);
   virtual ~Processor();
@@ -45,6 +49,7 @@ class Processor /*: public std::enable_shared_from_this<Processor>*/ {
 
   void RemoveChild(const std::shared_ptr<Processor> &child);
 
+  std::shared_ptr<Processor> GetParent();
   std::list<std::shared_ptr<Processor>> GetChilds();
 
   void SetPreProcessCallback(PreProcessCallback callback);
@@ -71,7 +76,8 @@ class Processor /*: public std::enable_shared_from_this<Processor>*/ {
  protected:
   virtual Object *OnCreateOutput() = 0;
   virtual bool OnProcess(
-      Object *const in, Object *const out, Processor *const parent) = 0;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent) = 0;
 
  private:
   /** Run in standalone thread. */
@@ -101,20 +107,44 @@ class Processor /*: public std::enable_shared_from_this<Processor>*/ {
   PostProcessCallback post_callback_;
   ProcessCallback callback_;
 
-  Processor *parent_;
+  // Processor *parent_;
+  std::shared_ptr<Processor> parent_;
   std::list<std::shared_ptr<Processor>> childs_;
 
   std::thread thread_;
 };
 
 template <typename T>
-void iterate_processors(
+void iterate_processors_PtoC_after(
     const T &processors, std::function<void(std::shared_ptr<Processor>)> fn) {
   for (auto &&proc : processors) {
     fn(proc);
-    iterate_processors(proc->GetChilds(), fn);
+    iterate_processors_PtoC_after(proc->GetChilds(), fn);
   }
 }
+template <typename T>
+void iterate_processors_PtoC_before(
+    const T &processors, std::function<void(std::shared_ptr<Processor>)> fn) {
+  for (auto &&proc : processors) {
+    iterate_processors_PtoC_before(proc->GetChilds(), fn);
+    fn(proc);
+  }
+}
+
+template <typename T>
+void iterate_processors_CtoP_before(
+    T processor, std::function<void(std::shared_ptr<Processor>)> fn) {
+  if (processor->GetParent() != nullptr)
+    iterate_processors_CtoP_before(processor->GetParent(), fn);
+  fn(processor);
+}
+template <typename T>
+void iterate_processors_CtoP_after(
+    T processor, std::function<void(std::shared_ptr<Processor>)> fn) {
+  fn(processor);
+  if (processor->GetParent() != nullptr)
+    iterate_processors_CtoP_after(processor->GetParent(), fn);
+}
 
 MYNTEYE_END_NAMESPACE
 
diff --git a/src/mynteye/api/processor/depth_processor.cc b/src/mynteye/api/processor/depth_processor.cc
index 9441132..b1cc940 100644
--- a/src/mynteye/api/processor/depth_processor.cc
+++ b/src/mynteye/api/processor/depth_processor.cc
@@ -45,7 +45,8 @@ Object *DepthProcessor::OnCreateOutput() {
 }
 
 bool DepthProcessor::OnProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   const ObjMat *input = Object::Cast<ObjMat>(in);
   ObjMat *output = Object::Cast<ObjMat>(out);
diff --git a/src/mynteye/api/processor/depth_processor.h b/src/mynteye/api/processor/depth_processor.h
index 6cfe591..69f2f6d 100644
--- a/src/mynteye/api/processor/depth_processor.h
+++ b/src/mynteye/api/processor/depth_processor.h
@@ -36,7 +36,8 @@ class DepthProcessor : public Processor {
  protected:
   Object *OnCreateOutput() override;
   bool OnProcess(
-      Object *const in, Object *const out, Processor *const parent) override;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent) override;
  private:
   std::shared_ptr<struct camera_calib_info_pair> calib_infos_;
 };
diff --git a/src/mynteye/api/processor/depth_processor_ocv.cc b/src/mynteye/api/processor/depth_processor_ocv.cc
index 8bdb6a9..0afb381 100644
--- a/src/mynteye/api/processor/depth_processor_ocv.cc
+++ b/src/mynteye/api/processor/depth_processor_ocv.cc
@@ -39,7 +39,8 @@ Object *DepthProcessorOCV::OnCreateOutput() {
 }
 
 bool DepthProcessorOCV::OnProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   const ObjMat *input = Object::Cast<ObjMat>(in);
   ObjMat *output = Object::Cast<ObjMat>(out);
diff --git a/src/mynteye/api/processor/depth_processor_ocv.h b/src/mynteye/api/processor/depth_processor_ocv.h
index bd503a2..1618713 100644
--- a/src/mynteye/api/processor/depth_processor_ocv.h
+++ b/src/mynteye/api/processor/depth_processor_ocv.h
@@ -33,7 +33,8 @@ class DepthProcessorOCV : public Processor {
  protected:
   Object *OnCreateOutput() override;
   bool OnProcess(
-      Object *const in, Object *const out, Processor *const parent) override;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent) override;
 };
 
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/api/processor/disparity_normalized_processor.cc b/src/mynteye/api/processor/disparity_normalized_processor.cc
index 9a629e8..dfa79fc 100644
--- a/src/mynteye/api/processor/disparity_normalized_processor.cc
+++ b/src/mynteye/api/processor/disparity_normalized_processor.cc
@@ -43,7 +43,8 @@ Object *DisparityNormalizedProcessor::OnCreateOutput() {
 }
 
 bool DisparityNormalizedProcessor::OnProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   const ObjMat *input = Object::Cast<ObjMat>(in);
   ObjMat *output = Object::Cast<ObjMat>(out);
diff --git a/src/mynteye/api/processor/disparity_normalized_processor.h b/src/mynteye/api/processor/disparity_normalized_processor.h
index 99d395b..1b61420 100644
--- a/src/mynteye/api/processor/disparity_normalized_processor.h
+++ b/src/mynteye/api/processor/disparity_normalized_processor.h
@@ -33,7 +33,8 @@ class DisparityNormalizedProcessor : public Processor {
  protected:
   Object *OnCreateOutput() override;
   bool OnProcess(
-      Object *const in, Object *const out, Processor *const parent) override;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent) override;
 };
 
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/api/processor/disparity_processor.cc b/src/mynteye/api/processor/disparity_processor.cc
index 70270f2..34a45d9 100644
--- a/src/mynteye/api/processor/disparity_processor.cc
+++ b/src/mynteye/api/processor/disparity_processor.cc
@@ -66,7 +66,6 @@ DisparityProcessor::DisparityProcessor(DisparityProcessorType type,
 #endif
 #ifdef WITH_BM_SOBEL_FILTER
   } else if (type_ == DisparityProcessorType::BM) {
-    int bmWinSize = 3;
 #ifdef WITH_OPENCV2
     LOG(ERROR) << "not supported in opencv 2.x";
     // int bmWinSize = 3;
@@ -147,7 +146,8 @@ Object *DisparityProcessor::OnCreateOutput() {
 }
 
 bool DisparityProcessor::OnProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   const ObjMat2 *input = Object::Cast<ObjMat2>(in);
   ObjMat *output = Object::Cast<ObjMat>(out);
diff --git a/src/mynteye/api/processor/disparity_processor.h b/src/mynteye/api/processor/disparity_processor.h
index 026de30..0bf90f2 100644
--- a/src/mynteye/api/processor/disparity_processor.h
+++ b/src/mynteye/api/processor/disparity_processor.h
@@ -49,7 +49,8 @@ class DisparityProcessor : public Processor {
  protected:
   Object *OnCreateOutput() override;
   bool OnProcess(
-      Object *const in, Object *const out, Processor *const parent) override;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent) override;
 
  private:
   cv::Ptr<cv::StereoSGBM> sgbm_matcher;
diff --git a/src/mynteye/api/processor/points_processor.cc b/src/mynteye/api/processor/points_processor.cc
index fd8f204..6903121 100644
--- a/src/mynteye/api/processor/points_processor.cc
+++ b/src/mynteye/api/processor/points_processor.cc
@@ -73,7 +73,8 @@ Object *PointsProcessor::OnCreateOutput() {
 }
 
 bool PointsProcessor::OnProcess(
-  Object *const in, Object *const out, Processor *const parent) {
+  Object *const in, Object *const out,
+  std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
 
   float fx = calib_infos_->left.K[0];
diff --git a/src/mynteye/api/processor/points_processor.h b/src/mynteye/api/processor/points_processor.h
index a2dbcdb..5cdf958 100644
--- a/src/mynteye/api/processor/points_processor.h
+++ b/src/mynteye/api/processor/points_processor.h
@@ -38,7 +38,8 @@ class PointsProcessor : public Processor {
  protected:
   Object *OnCreateOutput() override;
   bool OnProcess(
-      Object *const in, Object *const out, Processor *const parent) override;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent) override;
 
  private:
   std::shared_ptr<struct camera_calib_info_pair> calib_infos_;
diff --git a/src/mynteye/api/processor/points_processor_ocv.cc b/src/mynteye/api/processor/points_processor_ocv.cc
index d5aeda0..e0b4391 100644
--- a/src/mynteye/api/processor/points_processor_ocv.cc
+++ b/src/mynteye/api/processor/points_processor_ocv.cc
@@ -41,7 +41,8 @@ Object *PointsProcessorOCV::OnCreateOutput() {
 }
 
 bool PointsProcessorOCV::OnProcess(
-  Object *const in, Object *const out, Processor *const parent) {
+  Object *const in, Object *const out,
+  std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   const ObjMat *input = Object::Cast<ObjMat>(in);
   ObjMat *output = Object::Cast<ObjMat>(out);
diff --git a/src/mynteye/api/processor/points_processor_ocv.h b/src/mynteye/api/processor/points_processor_ocv.h
index cba2ee9..a0d2c0a 100644
--- a/src/mynteye/api/processor/points_processor_ocv.h
+++ b/src/mynteye/api/processor/points_processor_ocv.h
@@ -35,7 +35,8 @@ class PointsProcessorOCV : public Processor {
  protected:
   Object *OnCreateOutput() override;
   bool OnProcess(
-      Object *const in, Object *const out, Processor *const parent) override;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent) override;
 
  private:
   cv::Mat Q_;
diff --git a/src/mynteye/api/processor/rectify_processor.cc b/src/mynteye/api/processor/rectify_processor.cc
index a601e28..6648b8a 100644
--- a/src/mynteye/api/processor/rectify_processor.cc
+++ b/src/mynteye/api/processor/rectify_processor.cc
@@ -417,7 +417,8 @@ Object *RectifyProcessor::OnCreateOutput() {
 }
 
 bool RectifyProcessor::OnProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   const ObjMat2 *input = Object::Cast<ObjMat2>(in);
   ObjMat2 *output = Object::Cast<ObjMat2>(out);
diff --git a/src/mynteye/api/processor/rectify_processor.h b/src/mynteye/api/processor/rectify_processor.h
index 7ebe2d8..029ed6d 100644
--- a/src/mynteye/api/processor/rectify_processor.h
+++ b/src/mynteye/api/processor/rectify_processor.h
@@ -77,7 +77,8 @@ class RectifyProcessor : public Processor {
  protected:
   Object *OnCreateOutput() override;
   bool OnProcess(
-      Object *const in, Object *const out, Processor *const parent) override;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent) override;
 
  private:
   void InitParams(IntrinsicsEquidistant in_left,
diff --git a/src/mynteye/api/processor/rectify_processor_ocv.cc b/src/mynteye/api/processor/rectify_processor_ocv.cc
index 5decbb1..ca09be0 100644
--- a/src/mynteye/api/processor/rectify_processor_ocv.cc
+++ b/src/mynteye/api/processor/rectify_processor_ocv.cc
@@ -61,7 +61,8 @@ Object *RectifyProcessorOCV::OnCreateOutput() {
 }
 
 bool RectifyProcessorOCV::OnProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   const ObjMat2 *input = Object::Cast<ObjMat2>(in);
   ObjMat2 *output = Object::Cast<ObjMat2>(out);
diff --git a/src/mynteye/api/processor/rectify_processor_ocv.h b/src/mynteye/api/processor/rectify_processor_ocv.h
index e67c4ae..9c450ec 100644
--- a/src/mynteye/api/processor/rectify_processor_ocv.h
+++ b/src/mynteye/api/processor/rectify_processor_ocv.h
@@ -51,7 +51,8 @@ class RectifyProcessorOCV : public Processor {
  protected:
   Object *OnCreateOutput() override;
   bool OnProcess(
-      Object *const in, Object *const out, Processor *const parent) override;
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent) override;
 
  private:
   void InitParams(IntrinsicsPinhole in_left,
diff --git a/src/mynteye/api/synthetic.cc b/src/mynteye/api/synthetic.cc
index 54963d3..f6365d4 100644
--- a/src/mynteye/api/synthetic.cc
+++ b/src/mynteye/api/synthetic.cc
@@ -809,7 +809,8 @@ void Synthetic::ProcessNativeStream(
 }
 
 bool Synthetic::OnRectifyProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   if (plugin_ && plugin_->OnRectifyProcess(in, out)) {
     return true;
@@ -819,7 +820,8 @@ bool Synthetic::OnRectifyProcess(
 }
 
 bool Synthetic::OnDisparityProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   if (plugin_ && plugin_->OnDisparityProcess(in, out)) {
     return true;
@@ -828,7 +830,8 @@ bool Synthetic::OnDisparityProcess(
 }
 
 bool Synthetic::OnDisparityNormalizedProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   if (plugin_ && plugin_->OnDisparityNormalizedProcess(in, out)) {
     return true;
@@ -837,7 +840,8 @@ bool Synthetic::OnDisparityNormalizedProcess(
 }
 
 bool Synthetic::OnPointsProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   if (plugin_ && plugin_->OnPointsProcess(in, out)) {
     return true;
@@ -846,7 +850,8 @@ bool Synthetic::OnPointsProcess(
 }
 
 bool Synthetic::OnDepthProcess(
-    Object *const in, Object *const out, Processor *const parent) {
+    Object *const in, Object *const out,
+    std::shared_ptr<Processor> const parent) {
   MYNTEYE_UNUSED(parent)
   if (plugin_ && plugin_->OnDepthProcess(in, out)) {
     return true;
diff --git a/src/mynteye/api/synthetic.h b/src/mynteye/api/synthetic.h
index 3625a9f..976a378 100644
--- a/src/mynteye/api/synthetic.h
+++ b/src/mynteye/api/synthetic.h
@@ -88,15 +88,20 @@ class Synthetic {
   void ProcessNativeStream(const Stream &stream, const api::StreamData &data);
 
   bool OnRectifyProcess(
-      Object *const in, Object *const out, Processor *const parent);
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent);
   bool OnDisparityProcess(
-      Object *const in, Object *const out, Processor *const parent);
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent);
   bool OnDisparityNormalizedProcess(
-      Object *const in, Object *const out, Processor *const parent);
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent);
   bool OnPointsProcess(
-      Object *const in, Object *const out, Processor *const parent);
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent);
   bool OnDepthProcess(
-      Object *const in, Object *const out, Processor *const parent);
+      Object *const in, Object *const out,
+      std::shared_ptr<Processor> const parent);
 
   void OnRectifyPostProcess(Object *const out);
   void OnDisparityPostProcess(Object *const out);