diff --git a/river/io/Group.cpp b/river/io/Group.cpp
index ac414b8..afeeca0 100644
--- a/river/io/Group.cpp
+++ b/river/io/Group.cpp
@@ -124,7 +124,7 @@ void river::io::Group::stop() {
 	RIVER_ERROR(" have " << count << " interfaces ...");
 	if (count == 0) {
 		RIVER_ERROR("GROUP :::::::::::: STOP() [START]");
-		for (size_t iii=0; iii<m_list.size(); ++iii) {
+		for (int32_t iii=m_list.size()-1; iii>=0; --iii) {
 			if (m_list[iii] != nullptr) {
 				m_list[iii]->stop();
 			}
diff --git a/test/testEchoDelay.h b/test/testEchoDelay.h
index 99c4ebf..36feebb 100644
--- a/test/testEchoDelay.h
+++ b/test/testEchoDelay.h
@@ -27,6 +27,11 @@ namespace river_test_echo_delay {
 			std11::chrono::system_clock::time_point m_currentTick;
 			int32_t m_stateFB;
 			int32_t m_stateMic;
+			std::vector<uint64_t> m_delayListMic;
+			bool m_estimateVolumeInput;
+			int16_t m_volumeInputMax;
+			int16_t m_volumeInputMin;
+			float m_gain;
 		public:
 			TestClass(std11::shared_ptr<river::Manager> _manager) :
 			  m_manager(_manager),
@@ -35,7 +40,9 @@ namespace river_test_echo_delay {
 			  m_nextSampleCount(0),
 			  m_delayBetweenEvent(400),
 			  m_stateFB(3),
-			  m_stateMic(3) {
+			  m_stateMic(0),
+			  m_estimateVolumeInput(true),
+			  m_gain(-40) {
 				//Set stereo output:
 				std::vector<audio::channel> channelMap;
 				channelMap.push_back(audio::channel_frontLeft);
@@ -55,6 +62,7 @@ namespace river_test_echo_delay {
 				                                              std11::placeholders::_5,
 				                                              std11::placeholders::_6));
 				m_interfaceOut->addVolumeGroup("FLOW");
+				m_interfaceOut->setParameter("volume", "FLOW", etk::to_string(m_gain) + "dB");
 				
 				m_interfaceIn = m_manager->createInput(48000,
 				                                       channelMap,
@@ -96,54 +104,66 @@ namespace river_test_echo_delay {
 			                  const std::vector<audio::channel>& _map) {
 				int16_t* data = static_cast<int16_t*>(_data);
 				double baseCycle = 2.0*M_PI/(double)48000 * m_freq;
-				if (_time == std11::chrono::system_clock::time_point()) {
+				if (m_estimateVolumeInput == true) {
 					for (int32_t iii=0; iii<_nbChunk; iii++) {
-						for (int32_t jjj=0; jjj<_map.size(); jjj++) {
-							data[_map.size()*iii+jjj] = 0;
-						}
-					}
-					return;
-				}
-				if (m_nextTick == std11::chrono::system_clock::time_point()) {
-					m_nextTick = _time + m_delayBetweenEvent;
-					m_nextSampleCount = m_delayBetweenEvent.count()*int64_t(_frequency)/1000;
-					m_phase = -1;
-				}
-				//APPL_INFO("sample : " << m_nextSampleCount);
-				for (int32_t iii=0; iii<_nbChunk; iii++) {
-					if (m_nextSampleCount > 0) {
-						m_nextSampleCount--;
-					} else {
-						m_phase = 0;
-						m_nextSampleCount = m_delayBetweenEvent.count()*int64_t(_frequency)/1000;
-						m_currentTick = m_nextTick;
-						m_nextTick += m_delayBetweenEvent;
-					}
-					if (m_phase >= 0) {
 						for (int32_t jjj=0; jjj<_map.size(); jjj++) {
 							data[_map.size()*iii+jjj] = sin(m_phase) * 30000;
 						}
-						double newPhase = m_phase+baseCycle;
-						if (    m_phase < M_PI
-						     && newPhase >= M_PI) {
-							// the zero crossing position :
-							m_currentTick = getInterpolateTime(_time, iii, sin(m_phase) * 30000, sin(newPhase) * 30000, _frequency);
-							// start detection ...
-							m_stateFB = 0;
-							m_stateMic = 0;
-							APPL_WARNING("Time Pulse zero crossing: " << m_currentTick << " id=" << iii);
-						}
-						m_phase = newPhase;
+						m_phase += baseCycle;
 						if (m_phase >= 2*M_PI) {
-							m_phase = -1;
-							//m_freq += 50.0;
-							if (m_freq>20000.0) {
-								m_freq = 400.0;
+							m_phase -= 2*M_PI;
+						}
+					}
+				} else {
+					if (_time == std11::chrono::system_clock::time_point()) {
+						for (int32_t iii=0; iii<_nbChunk; iii++) {
+							for (int32_t jjj=0; jjj<_map.size(); jjj++) {
+								data[_map.size()*iii+jjj] = 0;
 							}
 						}
-					} else {
-						for (int32_t jjj=0; jjj<_map.size(); jjj++) {
-							data[_map.size()*iii+jjj] = 0;
+						return;
+					}
+					if (m_nextTick == std11::chrono::system_clock::time_point()) {
+						m_nextTick = _time + m_delayBetweenEvent;
+						m_nextSampleCount = m_delayBetweenEvent.count()*int64_t(_frequency)/1000;
+						m_phase = -1;
+					}
+					//APPL_INFO("sample : " << m_nextSampleCount);
+					for (int32_t iii=0; iii<_nbChunk; iii++) {
+						if (m_nextSampleCount > 0) {
+							m_nextSampleCount--;
+						} else {
+							m_phase = 0;
+							m_nextSampleCount = m_delayBetweenEvent.count()*int64_t(_frequency)/1000;
+							m_currentTick = m_nextTick;
+							m_nextTick += m_delayBetweenEvent;
+						}
+						if (m_phase >= 0) {
+							for (int32_t jjj=0; jjj<_map.size(); jjj++) {
+								data[_map.size()*iii+jjj] = sin(m_phase) * 30000;
+							}
+							double newPhase = m_phase+baseCycle;
+							if (    m_phase < M_PI
+							     && newPhase >= M_PI) {
+								// the zero crossing position :
+								m_currentTick = getInterpolateTime(_time, iii, sin(m_phase) * 30000, sin(newPhase) * 30000, _frequency);
+								// start detection ...
+								m_stateFB = 0;
+								m_stateMic = 0;
+								APPL_WARNING("Time Pulse zero crossing: " << m_currentTick << " id=" << iii);
+							}
+							m_phase = newPhase;
+							if (m_phase >= 2*M_PI) {
+								m_phase = -1;
+								//m_freq += 50.0;
+								if (m_freq>20000.0) {
+									m_freq = 400.0;
+								}
+							}
+						} else {
+							for (int32_t jjj=0; jjj<_map.size(); jjj++) {
+								data[_map.size()*iii+jjj] = 0;
+							}
 						}
 					}
 				}
@@ -169,42 +189,47 @@ namespace river_test_echo_delay {
 					APPL_ERROR("call wrong type ... (need int16_t)");
 				}
 				RIVER_SAVE_FILE_MACRO(int16_t, "REC_FeedBack.raw", _data, _nbChunk*_map.size());
-				const int16_t* data = static_cast<const int16_t*>(_data);
-				// Detect Zero crossing after a max/min ...
-				for (size_t iii=0; iii<_nbChunk; ++iii) {
-					//for (size_t jjj=0; jjj<_map.size(); ++jjj) {
-					size_t jjj=0; {
-						if (m_stateFB == 0) {
-							if (data[iii*_map.size() + jjj] > INT16_MAX/5) {
-								m_stateFB = 1;
-								APPL_VERBOSE("FB: detect Normal " << iii);
-							} else if (data[iii*_map.size() + jjj] < -INT16_MAX/5) {
-								m_stateFB = 2;
-								APPL_VERBOSE("FB: detect inverse " << iii);
+				if (m_estimateVolumeInput == true) {
+					// nothing to do ...
+				} else {
+					const int16_t* data = static_cast<const int16_t*>(_data);
+					// Detect Zero crossing after a max/min ...
+					for (size_t iii=0; iii<_nbChunk; ++iii) {
+						//for (size_t jjj=0; jjj<_map.size(); ++jjj) {
+						size_t jjj=0; {
+							if (m_stateFB == 0) {
+								if (data[iii*_map.size() + jjj] > INT16_MAX/5) {
+									m_stateFB = 1;
+									APPL_VERBOSE("FB: detect Normal " << iii);
+								} else if (data[iii*_map.size() + jjj] < -INT16_MAX/5) {
+									m_stateFB = 2;
+									APPL_VERBOSE("FB: detect inverse " << iii);
+								}
+							} else if (m_stateFB == 1) {
+								// normale phase
+								if (data[iii*_map.size() + jjj] <= 0) {
+									// detect inversion of signe ...
+									m_stateFB = 3;
+									std11::chrono::system_clock::time_point time = getInterpolateTime(_time, iii-1, data[(iii-1)*_map.size() + jjj], data[iii*_map.size() + jjj], _frequency);
+									APPL_VERBOSE("FB:  1 position -1:  " << iii-1 << " " << data[(iii-1)*_map.size() + jjj]);
+									APPL_VERBOSE("FB:  1 position  0: " << iii << " " << data[iii*_map.size() + jjj]);
+									
+									APPL_WARNING("FB:  1 time detected:     " << time << " delay = " << float((time-m_currentTick).count())/1000.0f << "µs");
+								}
+							} else if (m_stateFB == 2) {
+								// inverse phase
+								if (data[iii*_map.size() + jjj] >= 0) {
+									// detect inversion of signe ...
+									m_stateFB = 3;
+									std11::chrono::system_clock::time_point time = getInterpolateTime(_time, iii-1, data[(iii-1)*_map.size() + jjj], data[iii*_map.size() + jjj], _frequency);
+									APPL_VERBOSE("FB:  2 position -1: " << iii-1 << " " << data[(iii-1)*_map.size() + jjj]);
+									APPL_VERBOSE("FB:  2 position  0: " << iii << " " << data[iii*_map.size() + jjj]);
+									APPL_WARNING("FB:  2 time detected:     " << time << " delay = " << float((time-m_currentTick).count())/1000.0f << "µs");
+								}
+							} else if (m_stateFB == 3) {
+								// TODO : Detect the pic ...
+								// do nothing ...
 							}
-						} else if (m_stateFB == 1) {
-							// normale phase
-							if (data[iii*_map.size() + jjj] <= 0) {
-								// detect inversion of signe ...
-								m_stateFB = 3;
-								std11::chrono::system_clock::time_point time = getInterpolateTime(_time, iii-1, data[(iii-1)*_map.size() + jjj], data[iii*_map.size() + jjj], _frequency);
-								APPL_VERBOSE("FB:  1 position -1:  " << iii-1 << " " << data[(iii-1)*_map.size() + jjj]);
-								APPL_VERBOSE("FB:  1 position  0: " << iii << " " << data[iii*_map.size() + jjj]);
-								APPL_WARNING("FB:  1 time detected:     " << time << " delay = " << float((time-m_currentTick).count())/1000.0f << "µs");
-							}
-						} else if (m_stateFB == 2) {
-							// inverse phase
-							if (data[iii*_map.size() + jjj] >= 0) {
-								// detect inversion of signe ...
-								m_stateFB = 3;
-								std11::chrono::system_clock::time_point time = getInterpolateTime(_time, iii-1, data[(iii-1)*_map.size() + jjj], data[iii*_map.size() + jjj], _frequency);
-								APPL_VERBOSE("FB:  2 position -1: " << iii-1 << " " << data[(iii-1)*_map.size() + jjj]);
-								APPL_VERBOSE("FB:  2 position  0: " << iii << " " << data[iii*_map.size() + jjj]);
-								APPL_WARNING("FB:  2 time detected:     " << time << " delay = " << float((time-m_currentTick).count())/1000.0f << "µs");
-							}
-						} else if (m_stateFB == 3) {
-							// TODO : Detect the pic ...
-							// do nothing ...
 						}
 					}
 				}
@@ -220,62 +245,120 @@ namespace river_test_echo_delay {
 				}
 				RIVER_SAVE_FILE_MACRO(int16_t, "REC_Microphone.raw", _data, _nbChunk*_map.size());
 				const int16_t* data = static_cast<const int16_t*>(_data);
-				// Detect Zero crossing after a max/min ...
-				for (size_t iii=0; iii<_nbChunk; ++iii) {
-					//for (size_t jjj=0; jjj<_map.size(); ++jjj) {
-					size_t jjj=0; {
-						if (m_stateMic == 0) {
-							if (data[iii*_map.size() + jjj] > 400/*INT16_MAX/15*/) {
-								m_stateMic = 1;
-								APPL_VERBOSE("Mic: detect Normal " << iii);
-							} else if (data[iii*_map.size() + jjj] < -400/*INT16_MAX/15*/) {
-								m_stateMic = 2;
-								APPL_VERBOSE("Mic: detect inverse " << iii);
+				if (m_estimateVolumeInput == true) {
+					m_stateMic ++;
+					const int16_t* data = static_cast<const int16_t*>(_data);
+					if (m_stateMic <= 40) {
+						for (size_t iii=0; iii<_nbChunk*_map.size(); ++iii) {
+							//APPL_INFO("value=" << data[iii]);
+							m_volumeInputMax = std::max(int16_t(data[iii]), m_volumeInputMax);
+							m_volumeInputMin = std::min(int16_t(data[iii]), m_volumeInputMin);
+						}
+						if (m_stateMic == 40) {
+							m_volumeInputMax *= 2;
+							m_volumeInputMin *= 2;
+						}
+					} else if (m_stateMic <= 10000) {
+						int16_t valueMax = 0;
+						int16_t valueMin = 0;
+						for (size_t iii=0; iii<_nbChunk*_map.size(); ++iii) {
+							//APPL_INFO("value=" << data[iii]);
+							valueMax = std::max(int16_t(data[iii]), valueMax);
+							valueMin = std::min(int16_t(data[iii]), valueMin);
+						}
+						if (    valueMax > m_volumeInputMax
+						     && valueMin < m_volumeInputMin
+						     && (    m_gain == 0.0
+						          || (    valueMax > INT16_MAX/2
+						               && valueMin < INT16_MIN/2
+						             )
+						         )
+						   ) {
+							m_gain += 3.0f;
+							m_gain = std::min(m_gain, 0.0f);
+							m_interfaceOut->setParameter("volume", "FLOW", etk::to_string(m_gain) + "dB");
+							APPL_INFO("Set detection volume : " << m_gain << " m_stateMic=" << m_stateMic);
+							m_stateMic = 3;
+							m_phase = -1;
+							m_estimateVolumeInput = false;
+							return;
+						} else {
+							if (m_stateMic%2 == 0) {
+								if (m_gain == 0.0f) {
+									APPL_CRITICAL("Can not find the basicVolume ...");
+								}
+								// just update volume
+								m_gain += 1.0f;
+								m_gain = std::min(m_gain, 0.0f);
+								m_interfaceOut->setParameter("volume", "FLOW", etk::to_string(m_gain) + "dB");
 							}
-						} else if (m_stateMic == 1) {
-							// normale phase
-							if (data[iii*_map.size() + jjj] <= 0) {
-								// detect inversion of signe ...
-								m_stateFB = 3;
-								std11::chrono::system_clock::time_point time = getInterpolateTime(_time, iii-1, data[(iii-1)*_map.size() + jjj], data[iii*_map.size() + jjj], _frequency);
-								APPL_VERBOSE("MIC: 1 position -1: " << iii-1 << " " << data[(iii-1)*_map.size() + jjj]);
-								APPL_VERBOSE("MIC: 1 position  0: " << iii << " " << data[iii*_map.size() + jjj]);
-								APPL_WARNING("MIC: 1 time detected:     " << time << " delay = " << float((time-m_currentTick).count())/1000.0f << "µs");
+						}
+					}
+				} else {
+					// Detect Zero crossing after a max/min ...
+					for (size_t iii=0; iii<_nbChunk; ++iii) {
+						//for (size_t jjj=0; jjj<_map.size(); ++jjj) {
+						size_t jjj=0; {
+							if (m_stateMic == 0) {
+								if (data[iii*_map.size() + jjj] > 400/*INT16_MAX/15*/) {
+									m_stateMic = 1;
+									APPL_VERBOSE("Mic: detect Normal " << iii);
+								} else if (data[iii*_map.size() + jjj] < -400/*INT16_MAX/15*/) {
+									m_stateMic = 2;
+									APPL_VERBOSE("Mic: detect inverse " << iii);
+								}
+							} else if (m_stateMic == 1) {
+								// normale phase
+								if (data[iii*_map.size() + jjj] <= 0) {
+									// detect inversion of signe ...
+									m_stateMic = 3;
+									std11::chrono::system_clock::time_point time = getInterpolateTime(_time, iii-1, data[(iii-1)*_map.size() + jjj], data[iii*_map.size() + jjj], _frequency);
+									APPL_VERBOSE("MIC: 1 position -1: " << iii-1 << " " << data[(iii-1)*_map.size() + jjj]);
+									APPL_VERBOSE("MIC: 1 position  0: " << iii << " " << data[iii*_map.size() + jjj]);
+									std11::chrono::nanoseconds delay = time-m_currentTick;
+									int32_t sampleDalay = (delay.count()*_frequency)/1000000000LL;
+									APPL_WARNING("MIC: 1 time detected:     " << time << " delay = " << float(delay.count())/1000.0f << "µs  samples=" << sampleDalay);
+									m_delayListMic.push_back(delay.count());
+								}
+							} else if (m_stateMic == 2) {
+								// inverse phase
+								if (data[iii*_map.size() + jjj] >= 0) {
+									// detect inversion of signe ...
+									m_stateMic = 3;
+									std11::chrono::system_clock::time_point time = getInterpolateTime(_time, iii-1, data[(iii-1)*_map.size() + jjj], data[iii*_map.size() + jjj], _frequency);
+									APPL_VERBOSE("MIC: 2 position -1: " << iii-1 << " " << data[(iii-1)*_map.size() + jjj]);
+									APPL_VERBOSE("MIC: 2 position  0: " << iii << " " << data[iii*_map.size() + jjj]);
+									std11::chrono::nanoseconds delay = time-m_currentTick;
+									int32_t sampleDalay = (delay.count()*_frequency)/1000000000LL;
+									APPL_WARNING("MIC: 2 time detected:     " << time << " delay = " << float(delay.count())/1000.0f << "µs  samples=" << sampleDalay);
+									m_delayListMic.push_back(delay.count());
+								}
+							} else if (m_stateMic == 3) {
+								// TODO : Detect the pic ...
+								// do nothing ...
 							}
-						} else if (m_stateMic == 2) {
-							// inverse phase
-							if (data[iii*_map.size() + jjj] >= 0) {
-								// detect inversion of signe ...
-								m_stateMic = 3;
-								std11::chrono::system_clock::time_point time = getInterpolateTime(_time, iii-1, data[(iii-1)*_map.size() + jjj], data[iii*_map.size() + jjj], _frequency);
-								APPL_VERBOSE("MIC: 2 position -1: " << iii-1 << " " << data[(iii-1)*_map.size() + jjj]);
-								APPL_VERBOSE("MIC: 2 position  0: " << iii << " " << data[iii*_map.size() + jjj]);
-								APPL_WARNING("MIC: 2 time detected:     " << time << " delay = " << float((time-m_currentTick).count())/1000.0f << "µs");
-							}
-						} else if (m_stateMic == 3) {
-							// TODO : Detect the pic ...
-							// do nothing ...
 						}
 					}
 				}
-				/*
-				const int16_t* data = static_cast<const int16_t*>(_data);
-				int16_t value = 0;
-				for (size_t iii=0; iii<_nbChunk*_map.size(); ++iii) {
-					//APPL_INFO("value=" << data[iii]);
-					value = std::max(int16_t(std::abs(data[iii])), value);
-				}
-				APPL_INFO("Get data ... max=" << value);
-				*/
 			}
 			void run() {
 				m_interfaceOut->start();
 				m_interfaceIn->start();
-				m_interfaceFB->start();
-				usleep(30000000);
-				m_interfaceFB->stop();
+				//m_interfaceFB->start();
+				usleep(10000000);
+				//m_interfaceFB->stop();
 				m_interfaceIn->stop();
 				m_interfaceOut->stop();
+				
+				int64_t delayAverage = 0;
+				if (m_delayListMic.size() > 0) {
+					for (size_t iii=0; iii<m_delayListMic.size(); ++iii) {
+						delayAverage += m_delayListMic[iii];
+					}
+					delayAverage /= m_delayListMic.size();
+				}
+				int32_t sampleDalay = (delayAverage*48000)/1000000000LL;
+				APPL_ERROR("Average delay in ns : " << delayAverage << " nbSample=" << sampleDalay);
 			}
 	};