diff --git a/audio/channel.cpp b/audio/channel.cpp
index baf8bb4..1236545 100644
--- a/audio/channel.cpp
+++ b/audio/channel.cpp
@@ -6,8 +6,10 @@
 
 #include <audio/channel.h>
 #include <audio/debug.h>
+#include <etk/stdTools.h>
 
 static const char* listValues[] = {
+	"unknow",
 	"front-left",
 	"front-center",
 	"front-right",
@@ -67,35 +69,21 @@ std::ostream& audio::operator <<(std::ostream& _os, const std::vector<std::vecto
 	return _os;
 }
 
-static std::vector<std::string> split(const std::string& _input, char _val) {
-	std::vector<std::string> list;
-	size_t lastStartPos = 0;
-	for(size_t iii=0; iii<_input.size(); iii++) {
-		if (_input[iii]==_val) {
-			list.push_back(std::string(_input, lastStartPos, iii - lastStartPos));
-			lastStartPos = iii+1;
+enum audio::channel audio::getChannelFromString(const std::string& _value) {
+	for (int32_t iii=0; iii<listValuesSize; ++iii) {
+		if (_value == listValues[iii]) {
+			return static_cast<enum audio::channel>(iii);
 		}
 	}
-	if (lastStartPos<_input.size()) {
-		list.push_back(std::string(_input, lastStartPos));
-	}
-	return list;
+	AUDIO_ERROR("Can not convert : '" << _value << "' ...");
+	return audio::channel_unknow;
 }
 
-std::vector<enum audio::channel> audio::getChannelFromString(const std::string& _value) {
+std::vector<enum audio::channel> audio::getListChannelFromString(const std::string& _value) {
 	std::vector<enum audio::channel> out;
-	std::vector<std::string> listIO = split(_value, ';');
-	for (size_t iii=0; iii<listIO.size(); ++iii) {
-		int32_t tmpCount = out.size();
-		for (int32_t jjj=0; jjj<listValuesSize; ++jjj) {
-			if (listIO[iii] == listValues[jjj]) {
-				out.push_back(static_cast<enum audio::channel>(jjj));
-				break;
-			}
-		}
-		if (tmpCount == out.size()) {
-			AUDIO_ERROR("Can not convert : '" << _value << "' ...");
-		}
+	std::vector<std::string> list = etk::split(_value, ';');
+	for (auto &it : list) {
+		out.push_back(getChannelFromString(it));
 	}
 	return out;
 }
diff --git a/audio/channel.h b/audio/channel.h
index 91b30cd..cd1be4f 100644
--- a/audio/channel.h
+++ b/audio/channel.h
@@ -12,6 +12,7 @@
 
 namespace audio {
 	enum channel {
+		channel_unknow, //!< Error channel ...
 		channel_frontLeft, //!< channel Front Left
 		channel_frontCenter, //!< channel Front Center
 		channel_frontRight, //!< channel Front Right
@@ -25,7 +26,8 @@ namespace audio {
 	};
 	std::string getChannelString(enum audio::channel _obj);
 	std::string getChannelString(const std::vector<enum audio::channel>& _obj);
-	std::vector<enum audio::channel> getChannelFromString(const std::string& _value);
+	enum audio::channel getChannelFromString(const std::string& _value);
+	std::vector<enum audio::channel> getListChannelFromString(const std::string& _value);
 	std::ostream& operator <<(std::ostream& _os, enum audio::channel _obj);
 	std::ostream& operator <<(std::ostream& _os, const std::vector<enum audio::channel>& _obj);
 	std::ostream& operator <<(std::ostream& _os, const std::vector<std::vector<enum audio::channel>>& _obj);
diff --git a/audio/format.cpp b/audio/format.cpp
index f146b16..e6938c5 100644
--- a/audio/format.cpp
+++ b/audio/format.cpp
@@ -40,6 +40,7 @@ std::string audio::getFormatString(enum audio::format _value) {
 	return listValues[_value];
 }
 
+
 enum audio::format audio::getFormatFromString(const std::string& _value) {
 	for (int32_t iii=0; iii<listValuesSize; ++iii) {
 		if (_value == listValues[iii]) {
@@ -47,4 +48,33 @@ enum audio::format audio::getFormatFromString(const std::string& _value) {
 		}
 	}
 	return format_unknow;
+}
+
+std::vector<enum audio::format> audio::getListFormatFromString(const std::string& _value) {
+	std::vector<enum audio::format> out;
+	std::vector<std::string> list = etk::split(_value, ';');
+	for (auto &it : list) {
+		out.push_back(getFormatFromString(it));
+	}
+	return out;
+}
+
+uint32_t audio::getFormatBytes(audio::format _format) {
+	if (_format == audio::format_int8) {
+		return sizeof(int8_t);
+	} else if (_format == audio::format_int16) {
+		return sizeof(int16_t);
+	} else if (_format == audio::format_int16_on_int32) {
+		return sizeof(int32_t);
+	} else if (_format == audio::format_int24) {
+		return sizeof(int32_t);
+	} else if (_format == audio::format_int32) {
+		return sizeof(int32_t);
+	} else if (_format == audio::format_float) {
+		return sizeof(float);
+	} else if (_format == audio::format_double) {
+		return sizeof(double);
+	}
+	AUDIO_ERROR("undefined format : " << _format);
+	return 0;
 }
\ No newline at end of file
diff --git a/audio/format.h b/audio/format.h
index 4091047..4f6f430 100644
--- a/audio/format.h
+++ b/audio/format.h
@@ -20,10 +20,12 @@ namespace audio {
 		format_float, //!< Floating point (single precision)
 		format_double //!< Floating point (double precision)
 	};
-	std::string getFormatString(enum audio::format);
+	std::string getFormatString(enum audio::format _format);
 	enum audio::format getFormatFromString(const std::string& _value);
+	std::vector<enum audio::format> getListFormatFromString(const std::string& _value);
 	std::ostream& operator <<(std::ostream& _os, enum audio::format _obj);
 	std::ostream& operator <<(std::ostream& _os, const std::vector<enum audio::format>& _obj);
+	uint32_t getFormatBytes(enum audio::format _format);
 };