diff --git a/src/AvTranscoder/DatasStructures/AudioDesc.cpp b/src/AvTranscoder/DatasStructures/AudioDesc.cpp
index 02f812ec..11d15e9b 100644
--- a/src/AvTranscoder/DatasStructures/AudioDesc.cpp
+++ b/src/AvTranscoder/DatasStructures/AudioDesc.cpp
@@ -1,200 +1,38 @@
 #include "AudioDesc.hpp"
-#include "AudioFrame.hpp"
 
-extern "C" {
-#ifndef __STDC_CONSTANT_MACROS
-	#define __STDC_CONSTANT_MACROS
-#endif
-#include <libavcodec/avcodec.h>
-#include <libavformat/avformat.h>
-#include <libavutil/avutil.h>
-#include <libavutil/pixdesc.h>
-#include <libavutil/imgutils.h>
-#include <libavutil/mathematics.h>
-#include <libavutil/opt.h>
-#include <libavutil/error.h>
-}
-#include <iostream>
-#include <stdexcept>
-#include <sstream>
 #include <cassert>
 
 namespace avtranscoder
 {
 
 AudioDesc::AudioDesc( const std::string& codecName )
-	: m_codec( NULL )
-	, m_codecContext( NULL )
+	: EssenceDesc( codecName )
 {
-	if( codecName.size() )
-		setAudioCodec( codecName );
 }
 
 AudioDesc::AudioDesc( const AVCodecID codecId )
-	: m_codec( NULL )
-	, m_codecContext( NULL )
+	: EssenceDesc( codecId )
 {
-	setAudioCodec( codecId );
 }
 
-void AudioDesc::setAudioCodec( const std::string& codecName )
+AudioDesc::AudioDesc( const EssenceDesc& essenceDesc )
+	: EssenceDesc( essenceDesc.getCodecId() )
 {
-	avcodec_register_all();  // Warning: should be called only once
-	m_codec = avcodec_find_encoder_by_name( codecName.c_str() );
-	initCodecContext();
+	m_codec = essenceDesc.getCodec();
+	m_codecContext = essenceDesc.getCodecContext();
 }
 
-void AudioDesc::setAudioCodec( const AVCodecID codecId )
-{
-	avcodec_register_all();  // Warning: should be called only once
-	m_codec = avcodec_find_encoder( codecId );
-	initCodecContext();
-}
-
-void AudioDesc::setAudioParameters( const size_t sampleRate, const size_t channels, const AVSampleFormat sampleFormat )
-{
-	m_codecContext->sample_rate = sampleRate;
-	m_codecContext->channels    = channels;
-	m_codecContext->sample_fmt  = sampleFormat;
-}
-
-void AudioDesc::initCodecContext( )
-{
-	if( m_codec == NULL )
-	{
-		throw std::runtime_error( "unknown audio codec" );
-	}
-
-	if( ( m_codecContext = avcodec_alloc_context3( m_codec ) ) == NULL )
-	{
-		throw std::runtime_error( "unable to create context for audio context" );
-	}
-
-	// Set default codec parameters
-	if( avcodec_get_context_defaults3( m_codecContext, m_codec ) != 0 )
-	{
-		throw std::runtime_error( "unable to find audio codec default values" );
-	}
-}
-
-void AudioDesc::set( const std::string& key, const std::string& flag, const bool enable )
+AudioFrameDesc AudioDesc::getFrameDesc() const
 {
-	int error = 0;
-	int64_t optVal;
+	assert( m_codecContext != NULL );
+	AudioFrameDesc audioFrameDesc;
 	
-	const AVOption* flagOpt = av_opt_find( m_codecContext, flag.c_str(), key.c_str(), 0, 0 );
-
-	if( ! flagOpt )
-	{
-		std::cout << flag << std::endl << " : " << flagOpt->default_val.i64 << std::endl;
-		throw std::runtime_error( "unknown flag " + flag );
-	}
-
-	error = av_opt_get_int( m_codecContext, key.c_str(), AV_OPT_SEARCH_CHILDREN, &optVal );
-	if( error != 0 )
-	{
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "unknown key " + key + ": " + err );
-	}
-
-	if( enable )
-		optVal = optVal |  flagOpt->default_val.i64;
-	else
-		optVal = optVal &~ flagOpt->default_val.i64;
+	audioFrameDesc.setChannels( m_codecContext->channels );
+	audioFrameDesc.setSampleRate( m_codecContext->sample_rate );
+	audioFrameDesc.setSampleFormat( m_codecContext->sample_fmt );
+	// audioFrameDesc.setFps( 25 );
 	
-	error = av_opt_set_int( m_codecContext, key.c_str(), optVal, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + flag + ": " + err );
-	}
-}
-
-void AudioDesc::set( const std::string& key, const bool value )
-{
-	int error = av_opt_set_int( m_codecContext, key.c_str(), value, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + ( value ? "true" : "false" ) + ": " + err );
-	}
-}
-
-void AudioDesc::set( const std::string& key, const int value )
-{
-	//const AVOption* flagOpt = av_opt_find( m_codecContext, key.c_str(), NULL, 0, AV_OPT_SEARCH_CHILDREN );
-
-	int error = av_opt_set_int( m_codecContext, key.c_str(), value, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::ostringstream os;
-		os << value;
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + os.str() + ": " + err );
-	}
-}
-
-void AudioDesc::set( const std::string& key, const int num, const int den )
-{
-	AVRational ratio;
-	ratio.num = num;
-	ratio.den = den;
-	int error = av_opt_set_q( m_codecContext, key.c_str(), ratio, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::ostringstream os;
-		os << num << "/" << den;
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + os.str() + ": " + err );
-	}
-}
-
-void AudioDesc::set( const std::string& key, const double value )
-{
-	int error = av_opt_set_double( m_codecContext, key.c_str(), value, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::ostringstream os;
-		os << value;
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + os.str() + ": " + err );
-	}
-}
-
-void AudioDesc::set( const std::string& key, const std::string& value )
-{
-	int error = av_opt_set( m_codecContext, key.c_str(), value.c_str(), AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + value + ": " + err );
-	}
-}
-
-std::string AudioDesc::getAudioCodec() const
-{
-	assert( m_codecContext != NULL );
-	return avcodec_descriptor_get( m_codecContext->codec_id )->name;
-}
-
-AVCodecID AudioDesc::getAudioCodecId() const
-{
-	assert( m_codecContext != NULL );
-	return m_codecContext->codec_id;
+	return audioFrameDesc;
 }
 
 const size_t AudioDesc::getSampleRate() const
@@ -215,18 +53,12 @@ const AVSampleFormat AudioDesc::getSampleFormat() const
 	return m_codecContext->sample_fmt;
 }
 
-AudioFrameDesc AudioDesc::getFrameDesc() const
+
+void AudioDesc::setAudioParameters( const size_t sampleRate, const size_t channels, const AVSampleFormat sampleFormat )
 {
-	assert( m_codecContext != NULL );
-	AudioFrameDesc audioFrameDesc;
-	
-	audioFrameDesc.setChannels( m_codecContext->channels );
-	audioFrameDesc.setSampleRate( m_codecContext->sample_rate );
-	audioFrameDesc.setSampleFormat( m_codecContext->sample_fmt );
-	// audioFrameDesc.setFps( 25 );
-	
-	return audioFrameDesc;
+	m_codecContext->sample_rate = sampleRate;
+	m_codecContext->channels    = channels;
+	m_codecContext->sample_fmt  = sampleFormat;
 }
 
-
 }
diff --git a/src/AvTranscoder/DatasStructures/AudioDesc.hpp b/src/AvTranscoder/DatasStructures/AudioDesc.hpp
index d8f28abc..7663f07e 100644
--- a/src/AvTranscoder/DatasStructures/AudioDesc.hpp
+++ b/src/AvTranscoder/DatasStructures/AudioDesc.hpp
@@ -1,7 +1,6 @@
 #ifndef _AV_TRANSCODER_DATA_AUDIO_DESC_HPP_
 #define _AV_TRANSCODER_DATA_AUDIO_DESC_HPP_
 
-#include "Image.hpp"
 #include <string>
 
 extern "C" {
@@ -15,50 +14,26 @@ extern "C" {
 #include <libavcodec/avcodec.h>
 }
 
+#include <AvTranscoder/common.hpp>
+#include <AvTranscoder/DatasStructures/EssenceDesc.hpp>
 #include <AvTranscoder/DatasStructures/AudioFrame.hpp>
 
 namespace avtranscoder
 {
 
-class AvExport AudioDesc
+class AvExport AudioDesc : public EssenceDesc
 {
 public:
 	AudioDesc( const std::string& codecName = "" );
 	AudioDesc( const AVCodecID codecId );
-	
-	void setAudioCodec( const std::string& codecName );
-	void setAudioCodec( const AVCodecID codecId );
-
-	void setAudioParameters( const size_t sampleRate, const size_t channels, const AVSampleFormat sampleFormat );
-
-	void set( const std::string& key, const std::string& flag, const bool enable );
-	void set( const std::string& key, const bool value );
-	void set( const std::string& key, const int value );
-	void set( const std::string& key, const int num, const int den );
-	void set( const std::string& key, const double value );
-	void set( const std::string& key, const std::string& value );
+	AudioDesc( const EssenceDesc& essenceDesc );
 
-	std::string getAudioCodec()  const;
-	AVCodecID   getAudioCodecId()  const;
-	
+	AudioFrameDesc getFrameDesc() const;
 	const size_t getSampleRate() const;
 	const size_t getChannels() const;
 	const AVSampleFormat getSampleFormat() const;
-
-#ifndef SWIG
-	AVCodec*        getCodec()        const { return m_codec; }
-	AVCodecContext* getCodecContext() const { return m_codecContext; }
-#endif
-
-	AudioFrameDesc getFrameDesc() const;
 	
-private:
-	void initCodecContext( );
-
-	void checkError( int error );
-
-	AVCodec*        m_codec;
-	AVCodecContext* m_codecContext;
+	void setAudioParameters( const size_t sampleRate, const size_t channels, const AVSampleFormat sampleFormat );
 };
 
 }
diff --git a/src/AvTranscoder/DatasStructures/EssenceDesc.cpp b/src/AvTranscoder/DatasStructures/EssenceDesc.cpp
new file mode 100644
index 00000000..c9851175
--- /dev/null
+++ b/src/AvTranscoder/DatasStructures/EssenceDesc.cpp
@@ -0,0 +1,186 @@
+#include "EssenceDesc.hpp"
+
+extern "C" {
+#ifndef __STDC_CONSTANT_MACROS
+	#define __STDC_CONSTANT_MACROS
+#endif
+#include <libavutil/opt.h>
+#include <libavutil/error.h>
+}
+
+#include <iostream>
+#include <stdexcept>
+#include <sstream>
+#include <cassert>
+
+namespace avtranscoder {
+
+EssenceDesc::EssenceDesc( const std::string& codecName )
+	: m_codec( NULL )
+	, m_codecContext( NULL )
+{
+	if( codecName.size() )
+		setCodec( codecName );
+}
+
+EssenceDesc::EssenceDesc( const AVCodecID codecId )
+	: m_codec( NULL )
+	, m_codecContext( NULL )
+{
+	setCodec( codecId );
+}
+
+std::string EssenceDesc::getCodecName() const
+{
+	assert( m_codecContext != NULL );
+	return avcodec_descriptor_get( m_codecContext->codec_id )->name;
+}
+
+AVCodecID EssenceDesc::getCodecId() const
+{
+	assert( m_codecContext != NULL );
+	return m_codecContext->codec_id;
+}
+
+void EssenceDesc::setCodec( const std::string& codecName )
+{
+	avcodec_register_all();  // Warning: should be called only once
+	m_codec = avcodec_find_encoder_by_name( codecName.c_str() );
+	initCodecContext();
+}
+
+void EssenceDesc::setCodec( const AVCodecID codecId )
+{
+	avcodec_register_all();  // Warning: should be called only once
+	m_codec = avcodec_find_encoder( codecId );
+	initCodecContext();
+}
+
+void EssenceDesc::initCodecContext( )
+{
+	if( m_codec == NULL )
+	{
+		throw std::runtime_error( "unknown audio codec" );
+	}
+
+	if( ( m_codecContext = avcodec_alloc_context3( m_codec ) ) == NULL )
+	{
+		throw std::runtime_error( "unable to create context for audio context" );
+	}
+
+	// Set default codec parameters
+	if( avcodec_get_context_defaults3( m_codecContext, m_codec ) != 0 )
+	{
+		throw std::runtime_error( "unable to find audio codec default values" );
+	}
+}
+
+void EssenceDesc::set( const std::string& key, const std::string& flag, const bool enable )
+{
+	int error = 0;
+	int64_t optVal;
+	
+	const AVOption* flagOpt = av_opt_find( m_codecContext, flag.c_str(), key.c_str(), 0, 0 );
+
+	if( ! flagOpt )
+	{
+		std::cout << flag << std::endl << " : " << flagOpt->default_val.i64 << std::endl;
+		throw std::runtime_error( "unknown flag " + flag );
+	}
+
+	error = av_opt_get_int( m_codecContext, key.c_str(), AV_OPT_SEARCH_CHILDREN, &optVal );
+	if( error != 0 )
+	{
+		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
+		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
+		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
+		throw std::runtime_error( "unknown key " + key + ": " + err );
+	}
+
+	if( enable )
+		optVal = optVal |  flagOpt->default_val.i64;
+	else
+		optVal = optVal &~ flagOpt->default_val.i64;
+	
+	error = av_opt_set_int( m_codecContext, key.c_str(), optVal, AV_OPT_SEARCH_CHILDREN );
+	if( error != 0 )
+	{
+		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
+		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
+		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
+		throw std::runtime_error( "setting " + key + " parameter to " + flag + ": " + err );
+	}
+}
+
+void EssenceDesc::set( const std::string& key, const bool value )
+{
+	int error = av_opt_set_int( m_codecContext, key.c_str(), value, AV_OPT_SEARCH_CHILDREN );
+	if( error != 0 )
+	{
+		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
+		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
+		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
+		throw std::runtime_error( "setting " + key + " parameter to " + ( value ? "true" : "false" ) + ": " + err );
+	}
+}
+
+void EssenceDesc::set( const std::string& key, const int value )
+{
+	//const AVOption* flagOpt = av_opt_find( m_codecContext, key.c_str(), NULL, 0, AV_OPT_SEARCH_CHILDREN );
+
+	int error = av_opt_set_int( m_codecContext, key.c_str(), value, AV_OPT_SEARCH_CHILDREN );
+	if( error != 0 )
+	{
+		std::ostringstream os;
+		os << value;
+		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
+		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
+		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
+		throw std::runtime_error( "setting " + key + " parameter to " + os.str() + ": " + err );
+	}
+}
+
+void EssenceDesc::set( const std::string& key, const int num, const int den )
+{
+	AVRational ratio;
+	ratio.num = num;
+	ratio.den = den;
+	int error = av_opt_set_q( m_codecContext, key.c_str(), ratio, AV_OPT_SEARCH_CHILDREN );
+	if( error != 0 )
+	{
+		std::ostringstream os;
+		os << num << "/" << den;
+		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
+		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
+		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
+		throw std::runtime_error( "setting " + key + " parameter to " + os.str() + ": " + err );
+	}
+}
+
+void EssenceDesc::set( const std::string& key, const double value )
+{
+	int error = av_opt_set_double( m_codecContext, key.c_str(), value, AV_OPT_SEARCH_CHILDREN );
+	if( error != 0 )
+	{
+		std::ostringstream os;
+		os << value;
+		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
+		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
+		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
+		throw std::runtime_error( "setting " + key + " parameter to " + os.str() + ": " + err );
+	}
+}
+
+void EssenceDesc::set( const std::string& key, const std::string& value )
+{
+	int error = av_opt_set( m_codecContext, key.c_str(), value.c_str(), AV_OPT_SEARCH_CHILDREN );
+	if( error != 0 )
+	{
+		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
+		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
+		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
+		throw std::runtime_error( "setting " + key + " parameter to " + value + ": " + err );
+	}
+}
+
+}
diff --git a/src/AvTranscoder/DatasStructures/EssenceDesc.hpp b/src/AvTranscoder/DatasStructures/EssenceDesc.hpp
new file mode 100644
index 00000000..c75c7588
--- /dev/null
+++ b/src/AvTranscoder/DatasStructures/EssenceDesc.hpp
@@ -0,0 +1,61 @@
+#ifndef _AV_TRANSCODER_DATA_ESSENCE_DESC_HPP_
+#define	_AV_TRANSCODER_DATA_ESSENCE_DESC_HPP_
+
+#include <string>
+
+extern "C" {
+#ifndef __STDC_CONSTANT_MACROS
+	#define __STDC_CONSTANT_MACROS
+#endif
+#ifndef INT64_C
+	#define INT64_C(c) (c ## LL)
+	#define UINT64_C(c) (c ## ULL)
+#endif
+#include <libavcodec/avcodec.h>
+}
+
+#include <AvTranscoder/common.hpp>
+
+namespace avtranscoder
+{
+
+class AvExport EssenceDesc
+{
+public:
+	EssenceDesc( const std::string& codecName );
+	EssenceDesc( const AVCodecID codecId );
+	
+	virtual ~EssenceDesc() {}
+	
+	std::string getCodecName()  const;
+	AVCodecID   getCodecId()  const;
+	
+	void setCodec( const std::string& codecName );
+	void setCodec( const AVCodecID codecId );
+	
+	void set( const std::string& key, const std::string& flag, const bool enable );
+	void set( const std::string& key, const bool value );
+	void set( const std::string& key, const int value );
+	void set( const std::string& key, const int num, const int den );
+	void set( const std::string& key, const double value );
+	void set( const std::string& key, const std::string& value );
+	
+#ifndef SWIG
+	AVCodec*        getCodec()        const { return m_codec; }
+	AVCodecContext* getCodecContext() const { return m_codecContext; }
+#endif
+
+private:
+	void initCodecContext( );
+
+	void checkError( int error );
+
+protected:
+	AVCodec*        m_codec;
+	AVCodecContext* m_codecContext;
+};
+
+}
+
+#endif
+
diff --git a/src/AvTranscoder/DatasStructures/VideoDesc.cpp b/src/AvTranscoder/DatasStructures/VideoDesc.cpp
index c7dc4814..1060524c 100644
--- a/src/AvTranscoder/DatasStructures/VideoDesc.cpp
+++ b/src/AvTranscoder/DatasStructures/VideoDesc.cpp
@@ -1,53 +1,47 @@
 #include "VideoDesc.hpp"
 
-extern "C" {
-#ifndef __STDC_CONSTANT_MACROS
-	#define __STDC_CONSTANT_MACROS
-#endif
-#include <libavcodec/avcodec.h>
-#include <libavformat/avformat.h>
-#include <libavutil/avutil.h>
-#include <libavutil/pixdesc.h>
-#include <libavutil/imgutils.h>
-#include <libavutil/mathematics.h>
-#include <libavutil/opt.h>
-#include <libavutil/error.h>
-}
-#include <iostream>
-#include <stdexcept>
-#include <sstream>
 #include <cassert>
 
 namespace avtranscoder
 {
 
 VideoDesc::VideoDesc( const std::string& codecName )
-	: m_codec( NULL )
-	, m_codecContext( NULL )
+	: EssenceDesc( codecName )
 {
-	if( codecName.size() )
-		setVideoCodec( codecName );
 }
 
 VideoDesc::VideoDesc( const AVCodecID codecId )
-	: m_codec( NULL )
-	, m_codecContext( NULL )
+	: EssenceDesc( codecId )
 {
-	setVideoCodec( codecId );
 }
 
-void VideoDesc::setVideoCodec( const std::string& codecName )
+VideoDesc::VideoDesc( const EssenceDesc& essenceDesc )
+	: EssenceDesc( essenceDesc.getCodecId() )
+{
+	m_codec = essenceDesc.getCodec();
+	m_codecContext = essenceDesc.getCodecContext();
+}
+
+ImageDesc VideoDesc::getImageDesc() const
 {
-	avcodec_register_all();  // Warning: should be called only once
-	m_codec = avcodec_find_encoder_by_name( codecName.c_str() );
-	initCodecContext();
+	assert( m_codecContext != NULL );
+	ImageDesc imageDesc;
+	Pixel pixel( m_codecContext->pix_fmt );
+
+	imageDesc.setWidth ( m_codecContext->width  );
+	imageDesc.setHeight( m_codecContext->height );
+	imageDesc.setPixel ( pixel );
+	imageDesc.setDar   ( m_codecContext->height, m_codecContext->width );
+	return imageDesc;
 }
 
-void VideoDesc::setVideoCodec( const AVCodecID codecId )
+std::pair< size_t, size_t > VideoDesc::getTimeBase() const
 {
-	avcodec_register_all();  // Warning: should be called only once
-	m_codec = avcodec_find_encoder( codecId );
-	initCodecContext();
+	assert( m_codecContext != NULL );
+	std::pair< size_t, size_t > timeBase;
+	timeBase.first = m_codecContext->time_base.num;
+	timeBase.second = m_codecContext->time_base.den;
+	return timeBase;
 }
 
 void VideoDesc::setImageParameters( const ImageDesc& imageDesc )
@@ -75,165 +69,4 @@ void VideoDesc::setTimeBase( const size_t num, const size_t den, const size_t ti
 	m_codecContext->ticks_per_frame = ticksPerFrame;
 }
 
-std::string VideoDesc::getVideoCodec() const
-{
-	assert( m_codecContext != NULL );
-	return avcodec_descriptor_get( m_codecContext->codec_id )->name;
-}
-
-AVCodecID VideoDesc::getVideoCodecId() const
-{
-	assert( m_codecContext != NULL );
-	return m_codecContext->codec_id;
-}
-
-std::pair< size_t, size_t > VideoDesc::getTimeBase() const
-{
-	assert( m_codecContext != NULL );
-	std::pair< size_t, size_t > timeBase;
-	timeBase.first = m_codecContext->time_base.num;
-	timeBase.second = m_codecContext->time_base.den;
-	return timeBase;
-}
-
-void VideoDesc::initCodecContext( )
-{
-	if( m_codec == NULL )
-	{
-		throw std::runtime_error( "unknown video codec" );
-	}
-
-	if( ( m_codecContext = avcodec_alloc_context3( m_codec ) ) == NULL )
-	{
-		throw std::runtime_error( "unable to create context for video context" );
-	}
-
-	// Set default codec parameters
-	if( avcodec_get_context_defaults3( m_codecContext, m_codec ) != 0 )
-	{
-		throw std::runtime_error( "unable to find video codec default values" );
-	}
-}
-
-void VideoDesc::set( const std::string& key, const std::string& flag, const bool enable )
-{
-	int error = 0;
-	int64_t optVal;
-	
-	const AVOption* flagOpt = av_opt_find( m_codecContext, flag.c_str(), key.c_str(), 0, 0 );
-
-	if( ! flagOpt )
-	{
-		std::cout << flag << std::endl << " : " << flagOpt->default_val.i64 << std::endl;
-		throw std::runtime_error( "unknown flag " + flag );
-	}
-
-	error = av_opt_get_int( m_codecContext, key.c_str(), AV_OPT_SEARCH_CHILDREN, &optVal );
-	if( error != 0 )
-	{
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "unknown key " + key + ": " + err );
-	}
-
-	if( enable )
-		optVal = optVal |  flagOpt->default_val.i64;
-	else
-		optVal = optVal &~ flagOpt->default_val.i64;
-	
-	error = av_opt_set_int( m_codecContext, key.c_str(), optVal, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + flag + ": " + err );
-	}
-}
-
-void VideoDesc::set( const std::string& key, const bool value )
-{
-	int error = av_opt_set_int( m_codecContext, key.c_str(), value, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + ( value ? "true" : "false" ) + ": " + err );
-	}
-}
-
-void VideoDesc::set( const std::string& key, const int value )
-{
-	//const AVOption* flagOpt = av_opt_find( m_codecContext, key.c_str(), NULL, 0, AV_OPT_SEARCH_CHILDREN );
-
-	int error = av_opt_set_int( m_codecContext, key.c_str(), value, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::ostringstream os;
-		os << value;
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + os.str() + ": " + err );
-	}
-}
-
-void VideoDesc::set( const std::string& key, const int num, const int den )
-{
-	AVRational ratio;
-	ratio.num = num;
-	ratio.den = den;
-	int error = av_opt_set_q( m_codecContext, key.c_str(), ratio, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::ostringstream os;
-		os << num << "/" << den;
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + os.str() + ": " + err );
-	}
-}
-
-void VideoDesc::set( const std::string& key, const double value )
-{
-	int error = av_opt_set_double( m_codecContext, key.c_str(), value, AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::ostringstream os;
-		os << value;
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + os.str() + ": " + err );
-	}
-}
-
-void VideoDesc::set( const std::string& key, const std::string& value )
-{
-	int error = av_opt_set( m_codecContext, key.c_str(), value.c_str(), AV_OPT_SEARCH_CHILDREN );
-	if( error != 0 )
-	{
-		std::string err( "", AV_ERROR_MAX_STRING_SIZE );
-		//av_make_error_string( const_cast<char*>(err.c_str()), err.size(), error );
-		av_strerror( error, const_cast<char*>(err.c_str()), err.size() );
-		throw std::runtime_error( "setting " + key + " parameter to " + value + ": " + err );
-	}
-}
-
-ImageDesc VideoDesc::getImageDesc() const
-{
-	assert( m_codecContext != NULL );
-	ImageDesc imageDesc;
-	Pixel pixel( m_codecContext->pix_fmt );
-
-	imageDesc.setWidth ( m_codecContext->width  );
-	imageDesc.setHeight( m_codecContext->height );
-	imageDesc.setPixel ( pixel );
-	imageDesc.setDar   ( m_codecContext->height, m_codecContext->width );
-	return imageDesc;
-}
-
 }
diff --git a/src/AvTranscoder/DatasStructures/VideoDesc.hpp b/src/AvTranscoder/DatasStructures/VideoDesc.hpp
index 41239d3a..fe52c492 100644
--- a/src/AvTranscoder/DatasStructures/VideoDesc.hpp
+++ b/src/AvTranscoder/DatasStructures/VideoDesc.hpp
@@ -1,8 +1,6 @@
 #ifndef _AV_TRANSCODER_DATA_VIDEO_DESC_HPP_
 #define _AV_TRANSCODER_DATA_VIDEO_DESC_HPP_
 
-
-#include "Image.hpp"
 #include <string>
 
 extern "C" {
@@ -16,51 +14,28 @@ extern "C" {
 #include <libavcodec/avcodec.h>
 }
 
+#include <AvTranscoder/common.hpp>
+#include <AvTranscoder/DatasStructures/EssenceDesc.hpp>
 #include <AvTranscoder/DatasStructures/Image.hpp>
 
 namespace avtranscoder
 {
 
-class AvExport VideoDesc
+class AvExport VideoDesc : public EssenceDesc
 {
 public:
 	VideoDesc( const std::string& codecName = "" );
 	VideoDesc( const AVCodecID codecId );
-
-	void setVideoCodec( const std::string& codecName );
-	void setVideoCodec( const AVCodecID codecId );
-
+	VideoDesc( const EssenceDesc& essenceDesc );
+	
+	ImageDesc getImageDesc() const;
+	std::pair< size_t, size_t > getTimeBase() const;
+	
 	void setImageParameters( const ImageDesc& imageDesc );
 	void setImageParameters( const size_t width, const size_t height, const Pixel& pixel );
 	void setImageParameters( const size_t width, const size_t height, const AVPixelFormat& pixel );
 
 	void setTimeBase( const size_t num, const size_t den, const size_t ticksPerFrame = 1 );
-	
-	void set( const std::string& key, const std::string& flag, const bool enable );
-	void set( const std::string& key, const bool value );
-	void set( const std::string& key, const int value );
-	void set( const std::string& key, const int num, const int den );
-	void set( const std::string& key, const double value );
-	void set( const std::string& key, const std::string& value );
-
-	std::string getVideoCodec()  const;
-	AVCodecID   getVideoCodecId() const;
-	std::pair< size_t, size_t > getTimeBase() const;
-
-#ifndef SWIG
-	AVCodec*        getCodec()        const { return m_codec; }
-	AVCodecContext* getCodecContext() const { return m_codecContext; }
-#endif
-
-	ImageDesc getImageDesc() const;
-
-private:
-	void initCodecContext( );
-
-	void checkError( int error );
-
-	AVCodec*        m_codec;
-	AVCodecContext* m_codecContext;
 };
 
 }
diff --git a/src/AvTranscoder/EssenceStream/DummyVideo.cpp b/src/AvTranscoder/EssenceStream/DummyVideo.cpp
index bb2d9723..0113dbcb 100644
--- a/src/AvTranscoder/EssenceStream/DummyVideo.cpp
+++ b/src/AvTranscoder/EssenceStream/DummyVideo.cpp
@@ -17,7 +17,7 @@ DummyVideo::~DummyVideo( )
 {
 }
 
-void DummyVideo::setVideoDesc( VideoDesc& videoDesc )
+void DummyVideo::setVideoDesc( const VideoDesc& videoDesc )
 {
 	_videoDesc = videoDesc;
 	_imageDesc = _videoDesc.getImageDesc();
diff --git a/src/AvTranscoder/EssenceStream/DummyVideo.hpp b/src/AvTranscoder/EssenceStream/DummyVideo.hpp
index 46acb596..5f123d01 100644
--- a/src/AvTranscoder/EssenceStream/DummyVideo.hpp
+++ b/src/AvTranscoder/EssenceStream/DummyVideo.hpp
@@ -17,7 +17,7 @@ class AvExport DummyVideo : public InputEssence
 	~DummyVideo( );
 
 	// Stream properties
-	void setVideoDesc( VideoDesc& videoDesc );
+	void setVideoDesc( const VideoDesc& videoDesc );
 
 	VideoDesc getVideoDesc() const;
 	
diff --git a/src/AvTranscoder/EssenceStream/InputAudio.cpp b/src/AvTranscoder/EssenceStream/InputAudio.cpp
index 3c0b954d..1b7c3c6d 100644
--- a/src/AvTranscoder/EssenceStream/InputAudio.cpp
+++ b/src/AvTranscoder/EssenceStream/InputAudio.cpp
@@ -57,7 +57,7 @@ void InputAudio::setup()
 {
 	avcodec_register_all();
 
-	_codec = avcodec_find_decoder( _inputStream->getAudioDesc().getAudioCodecId() );
+	_codec = avcodec_find_decoder( _inputStream->getAudioDesc().getCodecId() );
 	if( _codec == NULL )
 	{
 		throw std::runtime_error( "codec not supported" );
diff --git a/src/AvTranscoder/EssenceStream/InputVideo.cpp b/src/AvTranscoder/EssenceStream/InputVideo.cpp
index 3dca6e79..6fe15edd 100644
--- a/src/AvTranscoder/EssenceStream/InputVideo.cpp
+++ b/src/AvTranscoder/EssenceStream/InputVideo.cpp
@@ -55,7 +55,7 @@ void InputVideo::setup()
 {
 	av_register_all();
 
-	_codec = avcodec_find_decoder( _inputStream->getVideoDesc().getVideoCodecId() );
+	_codec = avcodec_find_decoder( _inputStream->getVideoDesc().getCodecId() );
 	if( _codec == NULL )
 	{
 		throw std::runtime_error( "codec not supported" );
diff --git a/src/AvTranscoder/EssenceStream/OutputAudio.cpp b/src/AvTranscoder/EssenceStream/OutputAudio.cpp
index b5dceacd..bcc3a726 100644
--- a/src/AvTranscoder/EssenceStream/OutputAudio.cpp
+++ b/src/AvTranscoder/EssenceStream/OutputAudio.cpp
@@ -176,23 +176,23 @@ bool OutputAudio::encodeFrame( DataStream& codedFrame )
 #endif
 }
 
-void OutputAudio::setProfile( Profile::ProfileDesc& desc, const AudioFrameDesc& frameDesc  )
+void OutputAudio::setProfile( const Profile::ProfileDesc& desc, const AudioFrameDesc& frameDesc  )
 {
 	if( ! desc.count( Profile::avProfileCodec ) || 		
 		! desc.count( Profile::avProfileSampleFormat ) || 
 		! desc.count( Profile::avProfileSampleRate ) || 
 		! desc.count( Profile::avProfileChannel ) )
 	{
-		throw std::runtime_error( "The profile " + desc[ Profile::avProfileIdentificatorHuman ] + " is invalid." );
+		throw std::runtime_error( "The profile " + desc.find( Profile::avProfileIdentificatorHuman )->second + " is invalid." );
 	}
 	
-	_audioDesc.setAudioCodec( desc[ Profile::avProfileCodec ] );
+	_audioDesc.setCodec( desc.find( Profile::avProfileCodec )->second );
 	
-	size_t sample_rate = std::strtoul( desc[ Profile::avProfileSampleRate ].c_str(), NULL, 0 );
-	size_t channels = std::strtoul( desc[ Profile::avProfileChannel ].c_str(), NULL, 0 );
-	_audioDesc.setAudioParameters( sample_rate, channels, av_get_sample_fmt( desc[ Profile::avProfileSampleFormat ].c_str() ) );
+	size_t sample_rate = std::strtoul( desc.find( Profile::avProfileSampleRate )->second.c_str(), NULL, 0 );
+	size_t channels = std::strtoul( desc.find( Profile::avProfileChannel )->second.c_str(), NULL, 0 );
+	_audioDesc.setAudioParameters( sample_rate, channels, av_get_sample_fmt( desc.find( Profile::avProfileSampleFormat )->second.c_str() ) );
 	
-	for( Profile::ProfileDesc::iterator it = desc.begin(); it != desc.end(); ++it )
+	for( Profile::ProfileDesc::const_iterator it = desc.begin(); it != desc.end(); ++it )
 	{
 		if( (*it).first == Profile::avProfileIdentificator ||
 			(*it).first == Profile::avProfileIdentificatorHuman ||
@@ -215,7 +215,7 @@ void OutputAudio::setProfile( Profile::ProfileDesc& desc, const AudioFrameDesc&
 
 	setup();
 
-	for( Profile::ProfileDesc::iterator it = desc.begin(); it != desc.end(); ++it )
+	for( Profile::ProfileDesc::const_iterator it = desc.begin(); it != desc.end(); ++it )
 	{
 		if( (*it).first == Profile::avProfileIdentificator ||
 			(*it).first == Profile::avProfileIdentificatorHuman ||
diff --git a/src/AvTranscoder/EssenceStream/OutputAudio.hpp b/src/AvTranscoder/EssenceStream/OutputAudio.hpp
index aace4a58..4b3a4369 100644
--- a/src/AvTranscoder/EssenceStream/OutputAudio.hpp
+++ b/src/AvTranscoder/EssenceStream/OutputAudio.hpp
@@ -29,7 +29,7 @@ class OutputAudio : public OutputEssence
 	 */
 	bool encodeFrame( DataStream& codedFrame );
 	
-	void setProfile( Profile::ProfileDesc& desc, const AudioFrameDesc& frameDesc );
+	void setProfile( const Profile::ProfileDesc& desc, const AudioFrameDesc& frameDesc );
 
 	AudioDesc& getAudioDesc() { return _audioDesc; }
 
diff --git a/src/AvTranscoder/EssenceStream/OutputVideo.cpp b/src/AvTranscoder/EssenceStream/OutputVideo.cpp
index 2c6b8397..5817408e 100644
--- a/src/AvTranscoder/EssenceStream/OutputVideo.cpp
+++ b/src/AvTranscoder/EssenceStream/OutputVideo.cpp
@@ -186,23 +186,23 @@ bool OutputVideo::encodeFrame( DataStream& codedFrame )
 #endif
 }
 
-void OutputVideo::setProfile( Profile::ProfileDesc& desc, const avtranscoder::ImageDesc& imageDesc )
+void OutputVideo::setProfile( const Profile::ProfileDesc& desc, const avtranscoder::ImageDesc& imageDesc )
 {
 	if( ! desc.count( Profile::avProfileCodec ) ||
 		! desc.count( Profile::avProfilePixelFormat ) || 
 		! desc.count( Profile::avProfileFrameRate ) )
 	{
-		throw std::runtime_error( "The profile " + desc[ Profile::avProfileIdentificatorHuman ] + " is invalid." );
+		throw std::runtime_error( "The profile " + desc.find( Profile::avProfileIdentificatorHuman )->second + " is invalid." );
 	}
 	
-	_videoDesc.setVideoCodec( desc[ Profile::avProfileCodec ] );
+	_videoDesc.setCodec( desc.find( Profile::avProfileCodec )->second );
 	
-	const size_t frameRate = std::strtoul( desc[ Profile::avProfileFrameRate ].c_str(), NULL, 0 );
+	const size_t frameRate = std::strtoul( desc.find( Profile::avProfileFrameRate )->second.c_str(), NULL, 0 );
 	_videoDesc.setTimeBase( 1, frameRate );
 	
 	_videoDesc.setImageParameters( imageDesc );
 
-	for( Profile::ProfileDesc::iterator it = desc.begin(); it != desc.end(); ++it )
+	for( Profile::ProfileDesc::const_iterator it = desc.begin(); it != desc.end(); ++it )
 	{
 		if( (*it).first == Profile::avProfileIdentificator ||
 			(*it).first == Profile::avProfileIdentificatorHuman ||
@@ -224,7 +224,7 @@ void OutputVideo::setProfile( Profile::ProfileDesc& desc, const avtranscoder::Im
 
 	setup();
 
-	for( Profile::ProfileDesc::iterator it = desc.begin(); it != desc.end(); ++it )
+	for( Profile::ProfileDesc::const_iterator it = desc.begin(); it != desc.end(); ++it )
 	{
 		if( (*it).first == Profile::avProfileIdentificator ||
 			(*it).first == Profile::avProfileIdentificatorHuman ||
diff --git a/src/AvTranscoder/EssenceStream/OutputVideo.hpp b/src/AvTranscoder/EssenceStream/OutputVideo.hpp
index b7509088..c40add0c 100644
--- a/src/AvTranscoder/EssenceStream/OutputVideo.hpp
+++ b/src/AvTranscoder/EssenceStream/OutputVideo.hpp
@@ -44,7 +44,7 @@ class AvExport OutputVideo : public OutputEssence
 	 */
 	bool encodeFrame( DataStream& codedFrame );
 
-	void setProfile( Profile::ProfileDesc& desc, const avtranscoder::ImageDesc& imageDesc );
+	void setProfile( const Profile::ProfileDesc& desc, const avtranscoder::ImageDesc& imageDesc );
 	
 	VideoDesc& getVideoDesc() { return _videoDesc; }
 
diff --git a/src/AvTranscoder/Transcoder/StreamTranscoder.cpp b/src/AvTranscoder/Transcoder/StreamTranscoder.cpp
index 8b035455..34c6d70a 100644
--- a/src/AvTranscoder/Transcoder/StreamTranscoder.cpp
+++ b/src/AvTranscoder/Transcoder/StreamTranscoder.cpp
@@ -50,7 +50,7 @@ StreamTranscoder::StreamTranscoder(
 StreamTranscoder::StreamTranscoder(
 		InputStream& inputStream,
 		OutputFile& outputFile,
-		Profile::ProfileDesc& profile,
+		const Profile::ProfileDesc& profile,
 		const int subStreamIndex
 	)
 	: _inputStream( &inputStream )
@@ -78,7 +78,7 @@ StreamTranscoder::StreamTranscoder(
 
 			ImageDesc outputImageDesc = _inputStream->getVideoDesc().getImageDesc();
 
-			outputImageDesc.setPixel( Pixel( profile[ Profile::avProfilePixelFormat ].c_str() ) );
+			outputImageDesc.setPixel( Pixel( profile.find( Profile::avProfilePixelFormat )->second.c_str() ) );
 
 			outputVideo->setProfile( profile, outputImageDesc );
 			
@@ -129,7 +129,7 @@ StreamTranscoder::StreamTranscoder(
 StreamTranscoder::StreamTranscoder(
 		InputEssence& inputEssence,
 		OutputFile& outputFile,
-		Profile::ProfileDesc& profile
+		const Profile::ProfileDesc& profile
 	)
 	: _inputStream( NULL )
 	, _outputStream( NULL )
@@ -151,8 +151,8 @@ StreamTranscoder::StreamTranscoder(
 		OutputAudio* outputAudio = new OutputAudio();
 
 		_outputEssence = outputAudio;
-		AudioFrameDesc srcAudioFrameDesc; // @todo better solution ?
-		outputAudio->setProfile( profile, srcAudioFrameDesc );
+		AudioFrameDesc inputAudioFrameDesc = static_cast<DummyAudio*>( _inputEssence )->getAudioDesc().getFrameDesc();
+		outputAudio->setProfile( profile, inputAudioFrameDesc );
 		
 		static_cast<DummyAudio*>( _inputEssence )->setAudioDesc( outputAudio->getAudioDesc() );
 		
diff --git a/src/AvTranscoder/Transcoder/StreamTranscoder.hpp b/src/AvTranscoder/Transcoder/StreamTranscoder.hpp
index 74246c15..74858576 100644
--- a/src/AvTranscoder/Transcoder/StreamTranscoder.hpp
+++ b/src/AvTranscoder/Transcoder/StreamTranscoder.hpp
@@ -29,12 +29,12 @@ class StreamTranscoder
 	/**
 	 * @brief transcode stream
 	 **/
-	StreamTranscoder( InputStream& inputStream, OutputFile& outputFile, Profile::ProfileDesc& profile, const int subStreamIndex = -1 );
+	StreamTranscoder( InputStream& inputStream, OutputFile& outputFile, const Profile::ProfileDesc& profile, const int subStreamIndex = -1 );
 
 	/**
 	 * @brief encode from dummy stream
 	 **/
-	StreamTranscoder( InputEssence& inputEssence, OutputFile& outputFile, Profile::ProfileDesc& profile );
+	StreamTranscoder( InputEssence& inputEssence, OutputFile& outputFile, const Profile::ProfileDesc& profile );
 
 	~StreamTranscoder();
 
diff --git a/src/AvTranscoder/Transcoder/Transcoder.cpp b/src/AvTranscoder/Transcoder/Transcoder.cpp
index 51269f21..47588fbd 100644
--- a/src/AvTranscoder/Transcoder/Transcoder.cpp
+++ b/src/AvTranscoder/Transcoder/Transcoder.cpp
@@ -24,14 +24,14 @@ Transcoder::~Transcoder()
 	{
 		delete (*it);
 	}
-	// for( std::vector< DummyAudio* >::iterator it = _dummyAudio.begin(); it != _dummyAudio.end(); ++it )
-	// {
-	// 	delete (*it);
-	// }
-	// for( std::vector< DummyVideo* >::iterator it = _dummyVideo.begin(); it != _dummyVideo.end(); ++it )
-	// {
-	// 	delete (*it);
-	// }
+	for( std::vector< DummyAudio* >::iterator it = _dummyAudio.begin(); it != _dummyAudio.end(); ++it )
+	{
+		delete (*it);
+	}
+	for( std::vector< DummyVideo* >::iterator it = _dummyVideo.begin(); it != _dummyVideo.end(); ++it )
+	{
+		delete (*it);
+	}
 }
 
 void Transcoder::add( const std::string& filename, const size_t streamIndex, const std::string& profileName )
@@ -54,8 +54,7 @@ void Transcoder::add( const std::string& filename, const size_t streamIndex, Pro
 	if( ! filename.length() )
 	{
 		if( _verbose )
-			std::cout << "add encoding stream for dummy input" << std::endl;
-		addDummyStream( profileDesc );
+			std::cerr << "can't add a stream with no filename indicated" << std::endl;
 		return;
 	}
 
@@ -64,6 +63,22 @@ void Transcoder::add( const std::string& filename, const size_t streamIndex, Pro
 	addTranscodeStream( filename, streamIndex, profileDesc );
 }
 
+void Transcoder::add( const std::string& filename, const size_t streamIndex, Profile::ProfileDesc& profileDesc, EssenceDesc& essenceDesc )
+{
+	_profile.update( profileDesc );
+	if( ! filename.length() )
+	{
+		if( _verbose )
+			std::cout << "add dummy stream" << std::endl;
+		addDummyStream( profileDesc, essenceDesc );
+		return;
+	}
+	
+	if( _verbose )
+		std::cout << "add transcoding stream" << std::endl;
+	addTranscodeStream( filename, streamIndex, profileDesc );
+}
+
 void Transcoder::add( const std::string& filename, const size_t streamIndex, const int subStreamIndex, const std::string& profileName )
 {
 	if( subStreamIndex < 0 )
@@ -87,18 +102,41 @@ void Transcoder::add( const std::string& filename, const size_t streamIndex, con
 
 void Transcoder::add( const std::string& filename, const size_t streamIndex, const int subStreamIndex, Profile::ProfileDesc& profileDesc )
 {
+	_profile.update( profileDesc );
+	
 	if( subStreamIndex < 0 )
 	{
 		add( filename, streamIndex, profileDesc );
 		return;
 	}
+	
+	if( ! filename.length() )
+	{
+		if( _verbose )
+			std::cerr << "can't add a stream with no filename indicated" << std::endl;
+		return;
+	}
+
+	if( _verbose )
+		std::cout << "add transcoding stream for substream " << subStreamIndex << std::endl;
+	addTranscodeStream( filename, streamIndex, subStreamIndex, profileDesc );
+}
 
+void Transcoder::add( const std::string& filename, const size_t streamIndex, const int subStreamIndex, Profile::ProfileDesc& profileDesc, EssenceDesc& essenceDesc )
+{
 	_profile.update( profileDesc );
+	
+	if( subStreamIndex < 0 )
+	{
+		add( filename, streamIndex, profileDesc );
+		return;
+	}
+	
 	if( ! filename.length() )
 	{
 		if( _verbose )
-			std::cout << "add encoding stream for dummy input" << std::endl;
-		addDummyStream( profileDesc );
+			std::cout << "add dummy stream" << std::endl;
+		addDummyStream( profileDesc, essenceDesc );
 		return;
 	}
 
@@ -253,7 +291,7 @@ void Transcoder::addTranscodeStream( const std::string& filename, const size_t s
 	}
 }
 
-void Transcoder::addDummyStream( Profile::ProfileDesc& profile )
+void Transcoder::addDummyStream( const Profile::ProfileDesc& profile, const EssenceDesc& essenceDesc )
 {
 	if( ! profile.count( Profile::avProfileType ) )
 		throw std::runtime_error( "unable to found stream type (audio, video, etc.)" );
@@ -261,12 +299,16 @@ void Transcoder::addDummyStream( Profile::ProfileDesc& profile )
 	if( profile.find( Profile::avProfileType )->second == Profile::avProfileTypeAudio )
 	{
 		_dummyAudio.push_back( new DummyAudio() );
+		_dummyAudio.back()->setAudioDesc( static_cast<AudioDesc>( essenceDesc ) );
+		
 		_streamTranscoders.push_back( new StreamTranscoder( *_dummyAudio.back(), _outputFile, profile ) );
 	}
 
 	if( profile.find( Profile::avProfileType )->second == Profile::avProfileTypeVideo )
 	{
 		_dummyVideo.push_back( new DummyVideo() );
+		_dummyVideo.back()->setVideoDesc( static_cast<VideoDesc>( essenceDesc ) );
+		
 		_streamTranscoders.push_back( new StreamTranscoder( *_dummyVideo.back(), _outputFile, profile ) );
 	}
 }
diff --git a/src/AvTranscoder/Transcoder/Transcoder.hpp b/src/AvTranscoder/Transcoder/Transcoder.hpp
index 4aa790bc..d5f8d05c 100644
--- a/src/AvTranscoder/Transcoder/Transcoder.hpp
+++ b/src/AvTranscoder/Transcoder/Transcoder.hpp
@@ -27,7 +27,7 @@ class Transcoder
 
 	/**
 	 * @brief Add a stream and set a profile
-	 * @note If profile is empty, add a dummy stream.
+	 * @note If profileName is empty, rewrap.
 	 */
 	void add( const std::string& filename, const size_t streamIndex, const std::string& profileName = "" );
 
@@ -36,21 +36,33 @@ class Transcoder
 	 * @note Profile will be updated, be sure to pass unique profile name.
 	 */
 	void add( const std::string& filename, const size_t streamIndex, Profile::ProfileDesc& profileDesc );
-
+	/*
+	 * @note If filename is empty, add a dummy stream.
+	 */
+	void add( const std::string& filename, const size_t streamIndex, Profile::ProfileDesc& profileDesc, EssenceDesc& essenceDesc );
+	
 	/**
 	 * @brief Add a stream and set a profile
-	 * @note If profile is empty, add a dummy stream.
-	 * @note If subStreamIndex is negative, no substream a selected it's the stream. 
+	 * @note If profileName is empty, rewrap.
+	 * @note If subStreamIndex is negative, no substream is selected it's the stream. 
 	 */
 	void add( const std::string& filename, const size_t streamIndex, const int subStreamIndex, const std::string& profileName = "" );
 
 	/**
 	 * @brief Add a stream and set a custom profile
 	 * @note Profile will be updated, be sure to pass unique profile name.
-	 * @note If subStreamIndex is negative, no substream a selected it's the stream.
+	 * @note If subStreamIndex is negative, no substream is selected it's the stream.
 	 */
 	void add( const std::string& filename, const size_t streamIndex, const int subStreamIndex, Profile::ProfileDesc& profileDesc );
+	/**
+	 * @note If filename is empty, add a dummy stream.
+	 */
+	void add( const std::string& filename, const size_t streamIndex, const int subStreamIndex, Profile::ProfileDesc& profileDesc, EssenceDesc& essenceDesc );
 
+	/**
+	 * @brief Add the stream
+	 * @note The stream will be deleted in Transcoder's destructor.
+	 */
 	void add( StreamTranscoder& stream );
 	
 	bool processFrame();
@@ -67,7 +79,7 @@ class Transcoder
 
 	void addTranscodeStream( const std::string& filename, const size_t streamIndex, const size_t subStreamIndex, Profile::ProfileDesc& profile );
 
-	void addDummyStream( Profile::ProfileDesc& profile );
+	void addDummyStream( const Profile::ProfileDesc& profile, const EssenceDesc& essenceDesc );
 
 	InputFile* addInputFile( const std::string& filename, const size_t streamIndex );
 
diff --git a/src/AvTranscoder/avTranscoder.i b/src/AvTranscoder/avTranscoder.i
index ccf6e5a1..04715345 100644
--- a/src/AvTranscoder/avTranscoder.i
+++ b/src/AvTranscoder/avTranscoder.i
@@ -15,6 +15,7 @@
 #include <AvTranscoder/DatasStructures/Frame.hpp>
 #include <AvTranscoder/DatasStructures/Image.hpp>
 #include <AvTranscoder/DatasStructures/AudioFrame.hpp>
+#include <AvTranscoder/DatasStructures/EssenceDesc.hpp>
 #include <AvTranscoder/DatasStructures/VideoDesc.hpp>
 #include <AvTranscoder/DatasStructures/AudioDesc.hpp>
 #include <AvTranscoder/DatasStructures/DataStreamDesc.hpp>
@@ -67,6 +68,7 @@ namespace std {
 %include <AvTranscoder/DatasStructures/Frame.hpp>
 %include <AvTranscoder/DatasStructures/Image.hpp>
 %include <AvTranscoder/DatasStructures/AudioFrame.hpp>
+%include <AvTranscoder/DatasStructures/EssenceDesc.hpp>
 %include <AvTranscoder/DatasStructures/VideoDesc.hpp>
 %include <AvTranscoder/DatasStructures/AudioDesc.hpp>
 %include <AvTranscoder/DatasStructures/DataStreamDesc.hpp>

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