diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0563969..8d47c21 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -293,6 +293,7 @@ set(VMIX_SRCS
     TransitionView.cpp
     Source.cpp
     CloneSource.cpp
+    RenderSource.cpp
     SourceCallback.cpp
     SourceList.cpp
     Session.cpp
diff --git a/ImGuiVisitor.cpp b/ImGuiVisitor.cpp
index df87fc6..6f395b9 100644
--- a/ImGuiVisitor.cpp
+++ b/ImGuiVisitor.cpp
@@ -43,6 +43,7 @@
 #include "MediaPlayer.h"
 #include "MediaSource.h"
 #include "CloneSource.h"
+#include "RenderSource.h"
 #include "SessionSource.h"
 #include "PatternSource.h"
 #include "DeviceSource.h"
@@ -703,6 +704,12 @@ void ImGuiVisitor::visit (RenderSource& s)
     ImGui::Text("Rendering Output");
     if ( ImGui::Button(IMGUI_TITLE_PREVIEW, ImVec2(IMGUI_RIGHT_ALIGN, 0)) )
         Settings::application.widget.preview = true;
+
+    ImGui::SetNextItemWidth(IMGUI_RIGHT_ALIGN);
+    int m = (int) s.renderMode();
+    if (ImGui::Combo("Rendering", &m, RenderSource::render_mode_label, IM_ARRAYSIZE(RenderSource::render_mode_label)) )
+        s.setRenderMode((RenderSource::RenderSourceMode)m);
+
 }
 
 void ImGuiVisitor::visit (CloneSource& s)
@@ -720,13 +727,10 @@ void ImGuiVisitor::visit (CloneSource& s)
     if (ImGui::Combo("Image", &m, "Original\0Post-processed\0") )
         s.setImageMode((CloneSource::CloneImageMode)m);
 
-
     ImGui::SetNextItemWidth(IMGUI_RIGHT_ALIGN);
     float d = s.delay();
-//    if (ImGui::SliderFloat("Delay", &d, 0.f, 1.f, "%.2f s")){
-        if (ImGui::SliderFloat("Delay", &d, 0.f, 1.f, d < 0.01f ? "None" : "%.2f s")){
+    if (ImGui::SliderFloat("Delay", &d, 0.f, 1.f, d < 0.01f ? "None" : "%.2f s"))
         s.setDelay(d);
-    }
 
 }
 
diff --git a/InfoVisitor.cpp b/InfoVisitor.cpp
index 6b030b0..83addc4 100644
--- a/InfoVisitor.cpp
+++ b/InfoVisitor.cpp
@@ -39,6 +39,7 @@
 #include "MediaPlayer.h"
 #include "MediaSource.h"
 #include "CloneSource.h"
+#include "RenderSource.h"
 #include "SessionSource.h"
 #include "PatternSource.h"
 #include "DeviceSource.h"
@@ -172,7 +173,19 @@ void InfoVisitor::visit (RenderSource& s)
     if (current_id_ == s.id())
         return;
 
-    information_ = "Rendering Output";
+    std::ostringstream oss;
+    oss << "Rendering Output (" << RenderSource::render_mode_label[s.renderMode()];
+    oss << ") " << std::endl;
+
+    if (s.frame()){
+        oss << s.frame()->width() << " x " << s.frame()->height() << ", ";
+        if (s.frame()->use_alpha())
+            oss << "RGBA";
+        else
+            oss << "RGB";
+    }
+
+    information_ = oss.str();
     current_id_ = s.id();
 }
 
@@ -186,7 +199,10 @@ void InfoVisitor::visit (CloneSource& s)
 
     if (s.frame()){
         oss << s.frame()->width() << " x " << s.frame()->height() << ", ";
-        oss << "RGBA";
+        if (s.frame()->use_alpha())
+            oss << "RGBA";
+        else
+            oss << "RGB";
     }
 
     information_ = oss.str();
diff --git a/Mixer.cpp b/Mixer.cpp
index 7c034cb..03962a7 100644
--- a/Mixer.cpp
+++ b/Mixer.cpp
@@ -43,6 +43,7 @@
 #include "SessionVisitor.h"
 #include "SessionSource.h"
 #include "CloneSource.h"
+#include "RenderSource.h"
 #include "MediaSource.h"
 #include "PatternSource.h"
 #include "DeviceSource.h"
diff --git a/RenderSource.cpp b/RenderSource.cpp
new file mode 100644
index 0000000..da9591d
--- /dev/null
+++ b/RenderSource.cpp
@@ -0,0 +1,170 @@
+/*
+ * This file is part of vimix - video live mixer
+ *
+ * **Copyright** (C) 2019-2022 Bruno Herbelin <bruno.herbelin@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+**/
+
+#include <glm/gtc/matrix_transform.hpp>
+
+#include "defines.h"
+#include "Log.h"
+#include "FrameBuffer.h"
+#include "Decorations.h"
+#include "Resource.h"
+#include "Visitor.h"
+#include "Session.h"
+
+#include "RenderSource.h"
+
+const char* RenderSource::render_mode_label[2] = { "Loopback", "Non recursive" };
+
+RenderSource::RenderSource(uint64_t id) : Source(id), session_(nullptr), rendered_output_(nullptr), rendered_surface_(nullptr),
+    paused_(false), render_mode_(RENDER_TEXTURE)
+{
+    // set symbol
+    symbol_ = new Symbol(Symbol::RENDER, glm::vec3(0.75f, 0.75f, 0.01f));
+    symbol_->scale_.y = 1.5f;
+}
+
+RenderSource::~RenderSource()
+{
+    if (rendered_output_ != nullptr)
+        delete rendered_output_;
+}
+
+bool RenderSource::failed() const
+{
+    if ( rendered_output_ != nullptr && session_ != nullptr )
+        return rendered_output_->resolution() != session_->frame()->resolution();
+
+    return false;
+}
+
+uint RenderSource::texture() const
+{
+    if (rendered_output_ != nullptr)
+        return rendered_output_->texture();
+    else if (session_ && session_->frame())
+        return session_->frame()->texture();
+    else
+        return Resource::getTextureBlack(); // getTextureTransparent ?
+}
+
+//void RenderSource::setActive (bool on)
+//{
+
+//}
+
+void RenderSource::init()
+{
+    if (session_ && session_->frame() && session_->frame()->texture() != Resource::getTextureBlack()) {
+
+        FrameBuffer *fb = session_->frame();
+
+        // get the texture index from framebuffer of view for RENDER_TEXTURE mode
+//        rendered_surface_ = new Surface;
+//        rendered_surface_->setTextureIndex( fb->texture() );
+
+        // create the frame buffer displayed by the source (all modes)
+        rendered_output_ = new FrameBuffer( fb->resolution(), fb->use_alpha() );
+        // needs a first initialization
+        fb->blit(rendered_output_);
+
+        // set the texture index from internal framebuffer, apply it to the source texture surface
+        texturesurface_->setTextureIndex( rendered_output_->texture() );
+
+        // create Frame buffer matching size of output session
+        FrameBuffer *renderbuffer = new FrameBuffer( fb->resolution() );
+
+        // set the renderbuffer of the source and attach rendering nodes
+        attach(renderbuffer);
+
+        // deep update to reorder
+        ++View::need_deep_update_;
+
+        // done init
+        Log::Info("Source Render linked to session (%d x %d).", int(fb->resolution().x), int(fb->resolution().y) );
+    }
+}
+
+void RenderSource::update(float dt)
+{
+    static glm::mat4 projection = glm::ortho(-1.f, 1.f, 1.f, -1.f, -SCENE_DEPTH, 1.f);
+
+    if (active_ && !paused_ && session_ && rendered_output_) {
+
+        if (render_mode_ == RENDER_EXCLUSIVE) {
+            // temporarily exclude this RenderSource from the rendering
+            groups_[View::RENDERING]->visible_ = false;
+            // simulate a rendering of the session in a framebuffer
+            glm::mat4 P  = glm::scale( projection, glm::vec3(1.f / rendered_output_->aspectRatio(), 1.f, 1.f));
+            rendered_output_->begin();
+            // access to private RenderView in the session to call draw on the root of the scene
+            session_->render_.scene.root()->draw(glm::identity<glm::mat4>(), P);
+            rendered_output_->end();
+            // restore this RenderSource visibility
+            groups_[View::RENDERING]->visible_ = true;
+        }
+        else
+            session_->frame()->blit(rendered_output_);
+
+
+        //        rendered_output_->begin(true); // if not blit
+        //        rendered_surface_->draw(glm::identity<glm::mat4>(), rendered_output_->projection());
+        //        rendered_output_->end();
+    }
+
+    Source::update(dt);
+}
+
+void RenderSource::play (bool on)
+{
+    // toggle state
+    paused_ = !on;
+}
+
+void RenderSource::replay()
+{
+
+}
+
+
+glm::vec3 RenderSource::resolution() const
+{
+    if (rendered_output_ != nullptr)
+        return rendered_output_->resolution();
+    else if (session_ && session_->frame())
+        return session_->frame()->resolution();
+    else
+        return glm::vec3(0.f);
+}
+
+void RenderSource::accept(Visitor& v)
+{
+    Source::accept(v);
+//    if (!failed())
+        v.visit(*this);
+}
+
+glm::ivec2 RenderSource::icon() const
+{
+    return glm::ivec2(ICON_SOURCE_RENDER);
+}
+
+std::string RenderSource::info() const
+{
+    return std::string("Render loopback");
+}
diff --git a/RenderSource.h b/RenderSource.h
new file mode 100644
index 0000000..72759db
--- /dev/null
+++ b/RenderSource.h
@@ -0,0 +1,56 @@
+#ifndef RENDERSOURCE_H
+#define RENDERSOURCE_H
+
+#include "Source.h"
+
+
+
+class RenderSource : public Source
+{
+public:
+    RenderSource(uint64_t id = 0);
+    ~RenderSource();
+
+    // implementation of source API
+    void update (float dt) override;
+//    void setActive (bool on) override;
+    bool playing () const override { return !paused_; }
+    void play (bool) override;
+    void replay () override;
+    bool playable () const  override { return true; }
+    bool failed () const override;
+    uint texture() const override;
+    void accept (Visitor& v) override;
+
+    inline Session *session () const { return session_; }
+    inline void setSession (Session *se) { session_ = se; }
+
+    glm::vec3 resolution() const;
+
+    glm::ivec2 icon() const override;
+    std::string info() const override;
+
+    typedef enum {
+        RENDER_TEXTURE = 0,
+        RENDER_EXCLUSIVE
+    } RenderSourceMode;
+    static const char* render_mode_label[2];
+
+    void setRenderMode(RenderSourceMode m) { render_mode_ = m; }
+    RenderSourceMode renderMode() const { return render_mode_; }
+
+protected:
+
+    void init() override;
+    Session *session_;
+
+    FrameBuffer *rendered_output_;
+    Surface *rendered_surface_;
+
+    // control
+    bool paused_;
+    RenderSourceMode render_mode_;
+};
+
+
+#endif // RENDERSOURCE_H
diff --git a/Session.cpp b/Session.cpp
index 4a8c661..411e4b9 100644
--- a/Session.cpp
+++ b/Session.cpp
@@ -27,6 +27,7 @@
 #include "FrameGrabber.h"
 #include "SessionCreator.h"
 #include "SessionSource.h"
+#include "RenderSource.h"
 #include "MixingGroup.h"
 #include "Log.h"
 
@@ -129,11 +130,11 @@ void Session::update(float dt)
         else {
             if ( !(*it)->ready() )
                 ready = false;
-            // render the source
-            (*it)->render();
             // update the source
             (*it)->setActive(activation_threshold_);
             (*it)->update(dt);
+            // render the source // TODO: verify ok to render after update
+            (*it)->render();
         }
     }
 
diff --git a/Session.h b/Session.h
index 91dd49a..2b55018 100644
--- a/Session.h
+++ b/Session.h
@@ -32,6 +32,8 @@ struct SessionSnapshots {
 
 class Session
 {
+    friend class RenderSource;
+
 public:
     Session();
     ~Session();
diff --git a/SessionCreator.cpp b/SessionCreator.cpp
index 87ec47a..d9e8df0 100644
--- a/SessionCreator.cpp
+++ b/SessionCreator.cpp
@@ -34,6 +34,7 @@
 #include "NetworkSource.h"
 #include "MultiFileSource.h"
 #include "StreamSource.h"
+#include "RenderSource.h"
 #include "Session.h"
 #include "ImageShader.h"
 #include "ImageProcessingShader.h"
@@ -973,6 +974,12 @@ void SessionLoader::visit (SessionGroupSource& s)
 
 void SessionLoader::visit (RenderSource& s)
 {
+    // set attributes
+    int mode = 0;
+    xmlCurrent_->QueryIntAttribute("renderMode", &mode);
+    s.setRenderMode((RenderSource::RenderSourceMode)mode);
+
+    // set session
     s.setSession( session_ );
 }
 
diff --git a/SessionSource.cpp b/SessionSource.cpp
index 7e034e4..5ec30cf 100644
--- a/SessionSource.cpp
+++ b/SessionSource.cpp
@@ -382,77 +382,3 @@ std::string SessionGroupSource::info() const
     else
         return std::string("undefined group.");
 }
-
-RenderSource::RenderSource(uint64_t id) : Source(id), session_(nullptr)
-{
-    // set symbol
-    symbol_ = new Symbol(Symbol::RENDER, glm::vec3(0.75f, 0.75f, 0.01f));
-    symbol_->scale_.y = 1.5f;
-}
-
-bool RenderSource::failed() const
-{
-    if ( renderbuffer_ != nullptr && session_ != nullptr )
-        return renderbuffer_->resolution() != session_->frame()->resolution();
-
-    return false;
-}
-
-uint RenderSource::texture() const
-{
-    if (session_ && session_->frame())
-        return session_->frame()->texture();
-    else
-        return Resource::getTextureBlack(); // getTextureTransparent ?
-}
-
-void RenderSource::init()
-{
-    if (session_ && session_->frame() && session_->frame()->texture() != Resource::getTextureBlack()) {
-
-        FrameBuffer *fb = session_->frame();
-
-        // get the texture index from framebuffer of view, apply it to the surface
-        texturesurface_->setTextureIndex( fb->texture() );
-
-        // create Frame buffer matching size of output session
-        FrameBuffer *renderbuffer = new FrameBuffer( fb->resolution() );
-
-        // set the renderbuffer of the source and attach rendering nodes
-        attach(renderbuffer);
-
-        // deep update to reorder
-        ++View::need_deep_update_;
-
-        // done init
-        Log::Info("Source Render linked to session (%d x %d).", int(fb->resolution().x), int(fb->resolution().y) );
-    }
-}
-
-
-glm::vec3 RenderSource::resolution() const
-{
-    if (renderbuffer_ != nullptr)
-        return renderbuffer_->resolution();
-    else if (session_ && session_->frame())
-        return session_->frame()->resolution();
-    else
-        return glm::vec3(0.f);
-}
-
-void RenderSource::accept(Visitor& v)
-{
-    Source::accept(v);
-//    if (!failed())
-        v.visit(*this);
-}
-
-glm::ivec2 RenderSource::icon() const
-{
-    return glm::ivec2(ICON_SOURCE_RENDER);
-}
-
-std::string RenderSource::info() const
-{
-    return std::string("Render loopback");
-}
diff --git a/SessionSource.h b/SessionSource.h
index f6dd63f..c74d8a8 100644
--- a/SessionSource.h
+++ b/SessionSource.h
@@ -83,33 +83,4 @@ protected:
     glm::vec3 resolution_;
 };
 
-
-class RenderSource : public Source
-{
-public:
-    RenderSource(uint64_t id = 0);
-
-    // implementation of source API
-    bool playing () const override { return true; }
-    void play (bool) override {}
-    bool playable () const  override { return false; }
-    bool failed () const override;
-    uint texture() const override;
-    void accept (Visitor& v) override;
-
-    inline Session *session () const { return session_; }
-    inline void setSession (Session *se) { session_ = se; }
-
-    glm::vec3 resolution() const;
-
-    glm::ivec2 icon() const override;
-    std::string info() const override;
-
-protected:
-
-    void init() override;
-    Session *session_;
-};
-
-
 #endif // SESSIONSOURCE_H
diff --git a/SessionVisitor.cpp b/SessionVisitor.cpp
index 10a309c..9a75e9f 100644
--- a/SessionVisitor.cpp
+++ b/SessionVisitor.cpp
@@ -29,6 +29,7 @@ using namespace tinyxml2;
 #include "Decorations.h"
 #include "Source.h"
 #include "CloneSource.h"
+#include "RenderSource.h"
 #include "MediaSource.h"
 #include "Session.h"
 #include "SessionSource.h"
@@ -626,9 +627,10 @@ void SessionVisitor::visit (SessionGroupSource& s)
 
 }
 
-void SessionVisitor::visit (RenderSource&)
+void SessionVisitor::visit (RenderSource& s)
 {
     xmlCurrent_->SetAttribute("type", "RenderSource");
+    xmlCurrent_->SetAttribute("renderMode", (int) s.renderMode());
 }
 
 void SessionVisitor::visit (CloneSource& s)
diff --git a/UserInterfaceManager.cpp b/UserInterfaceManager.cpp
index f22eb45..8c777d3 100644
--- a/UserInterfaceManager.cpp
+++ b/UserInterfaceManager.cpp
@@ -77,6 +77,7 @@ using namespace std;
 #include "FrameBuffer.h"
 #include "MediaPlayer.h"
 #include "CloneSource.h"
+#include "RenderSource.h"
 #include "MediaSource.h"
 #include "SessionSource.h"
 #include "PatternSource.h"