diff --git a/os/include/audio_session/audio_session.h b/os/include/audio_session/audio_session.h
new file mode 100644
index 000000000..0f6675a20
--- /dev/null
+++ b/os/include/audio_session/audio_session.h
@@ -0,0 +1,330 @@
+/*
+ * \brief  Audio_out session interface
+ * \author Sebastian Sumpf
+ * \date   2012-12-20
+ *
+ * An audio session corresponds to one output channel, which can be used to send
+ * audio frames. Each session consists of an 'Audio_out::Stream' object that resides
+ * in shared memory between the client and the server. The 'Audio_out::Stream' in
+ * turn consists of 'Audio_out::Packet's that contain the actual frames. Each packet
+ * within a stream is freely accessible or may be allocated successively. Also
+ * there is a current position pointer for each stream that is updated by the
+ * server. This way it is possible to send one time events that need immediate
+ * processing  as well as streams that rely on buffering.
+ *
+ * Audio_out channel identifiers (loosely related to WAV channels) are:
+ *
+ * * front left (or left), front right (or right), front center
+ * * lfe (low frequency effects, subwoofer)
+ * * rear left, rear right, rear center
+ *
+ * For example, consumer-oriented 6-channel (5.1) audio uses front
+ * left/right/center, rear left/right and lfe.
+ *
+ * Note: That most components right now only support: "(front) left" and
+ * "(front) right".
+ *
+ */
+
+/*
+ * Copyright (C) 2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _INCLUDE__AUDIO_SESSION__AUDIO_SESSION_H_
+#define _INCLUDE__AUDIO_SESSION__AUDIO_SESSION_H_
+
+#include <base/allocator.h>
+#include <dataspace/capability.h>
+#include <base/rpc.h>
+#include <session/session.h>
+
+namespace Audio_out {
+	class Packet;
+	class Stream;
+	class Session;
+
+	enum {
+		QUEUE_SIZE  = 16,            /* buffer queue size */
+		PERIOD      = 2048,          /* samples per period */
+		SAMPLE_RATE = 44100,
+		SAMPLE_SIZE = sizeof(float),
+	};
+}
+
+/**
+ * Audio_out packet containing frames
+ */
+class Audio_out::Packet
+{
+	private:
+
+		friend class Session_client;
+		friend class Stream;
+
+		bool  _valid;
+		bool  _wait_for_play;
+		float _data[PERIOD];
+
+		void _submit() { _valid = true; _wait_for_play = true; }
+		void _alloc() { _wait_for_play = false; _valid = false; }
+
+	public:
+
+		Packet() : _valid(false), _wait_for_play(false) { }
+
+		/**
+		 * Copy data into packet, if there are less frames given than 'PERIOD',
+		 * then the remainder is filled with zeros
+		 *
+		 * \param  data  frames to copy in
+		 * \param  size  number of frames to copy
+		 */
+		void content(float *data, Genode::size_t samples)
+		{
+			Genode::memcpy(_data, data, (samples > PERIOD ? PERIOD : samples) * SAMPLE_SIZE);
+
+			if (samples < PERIOD)
+				Genode::memset(data + samples, 0, (PERIOD - samples) * SAMPLE_SIZE);
+		}
+
+		/**
+		 * Get content
+		 *
+		 * \return  pointer to frame data
+		 */
+		float *content() { return _data; }
+
+		/**
+		 * Play state
+		 *
+		 * \return  true if the packet has been played back; false otherwise
+		 */
+		bool played() const { return !_wait_for_play; }
+
+		/**
+		 * Valid state
+		 *
+		 * The valid state of a packet describes that the packet has been
+		 * processed by the server, it may not have been played back if the packet
+		 * is invalid. For example if a server is some filter, the audio may not
+		 * have been processed by the audio output driver.
+		 *
+		 * \return  true packet has *not* been processed yet; false otherwise
+		 */
+		bool valid() const { return _valid; }
+		Genode::size_t size() const { return sizeof(_data); }
+
+
+		/**********************************************
+		 ** Intended to be called by the server side **
+		 **********************************************/
+
+		/**
+		 * Invalidate packet thus marking it as processed
+		 */
+		void invalidate() { _valid = false; }
+
+		/**
+		 * Mark a packet as played
+		 */
+		void mark_as_played() { _wait_for_play = false; }
+};
+
+
+/**
+ * The audio stream object containing packets
+ *
+ * The stream object is created upon session creation. The server will
+ * allocate a dataspace on the clients account, the client session will then request this
+ * dataspace as well and both will attach it in there protection domains.
+ * After that the stream pointer within a session will be pointed to the
+ * attached dataspace on both sides. Therefore the constructor of the 'Stream'
+ * object will never be called.
+ */
+class Audio_out::Stream
+{
+	private:
+
+		unsigned  _pos;             /* current playback position */
+		unsigned  _tail;            /* tail pointer used for allocations */
+		Packet    _buf[QUEUE_SIZE]; /* packet queue */
+
+	public:
+
+		/**
+		 * Exceptions
+		 */
+		class Alloc_failed { };
+
+		/**
+		 * Current audio playback position
+		 *
+		 * \return  position
+		 */
+		unsigned pos()  const { return _pos; }
+
+
+		/**
+		 * Retrieve next packet for given packet
+		 *
+		 * \param  packet  preceding packet
+		 *
+		 * \return         Successor of packet or successor of current position if
+		 *                 'packet' is zero
+		 */
+		Packet *next(Packet *packet = 0)
+		{
+			return packet ? get(packet_position(packet) + 1) : get(pos() + 1);
+		}
+
+		/**
+		 * Retrieves the position of a given packet in the stream queue
+		 *
+		 * \param  packet  a packet
+		 * 
+		 * \return         position in stream queue
+		 */
+		unsigned packet_position(Packet *packet) { return packet - &_buf[0]; }
+
+
+		/**
+		 * Check if stream queue is full/empty
+		 */
+		bool empty() const
+		{
+			bool valid = false;
+			for (int i = 0; i < QUEUE_SIZE; i++)
+				valid |= _buf[i].valid();
+
+			return !valid;
+		}
+
+		bool full() const { return (_tail + 1) % QUEUE_SIZE == _pos; }
+
+
+		/**
+		 * Retrieve an audio at given position
+		 *
+		 * \param  pos  position in stream
+		 * 
+		 * \retun  Audio_out packet
+		 */
+		Packet *get(unsigned pos) { return &_buf[pos % QUEUE_SIZE]; }
+
+		
+		/**
+		 * Allocate a packet in stream
+		 *
+		 * \return  Packet
+		 * \throw   Alloc_failed  when stream queue is full
+		 */
+		Packet *alloc()
+		{
+			if (full())
+				throw Alloc_failed();
+
+			unsigned pos = _tail;
+			_tail = (_tail + 1) % QUEUE_SIZE;
+
+			Packet *p = get(pos);
+			p->_alloc();
+
+			return p;
+		}
+
+		/**
+		 * Reset stream queue, this means that allocation will start at current
+		 * queue position
+		 */
+		void reset() { _tail = _pos; }
+
+
+		/**********************************************
+		 ** Intended to be called by the server side **
+		 ***********************************************/
+
+		 /**
+			* Set current stream position
+			*
+			* \param pos  current position
+			*/
+		void pos(unsigned p) { _pos = p; }
+
+		/**
+		 * Increment current stream position by one
+		 */
+		void increment_position() { _pos = (_pos + 1) % QUEUE_SIZE; }
+};
+
+
+/**
+ * Audio_out session base
+ */
+class Audio_out::Session : public Genode::Session
+{
+	protected:
+
+		Stream *_stream;
+
+	public:
+
+		static const char *service_name() { return "Audio_out"; }
+
+		/**
+		 * Return stream of this session, see 'Stream' above
+		 */
+		Stream *stream() const { return _stream; }
+
+		/**
+		 * Start playback (alloc and submit packets after calling 'start')
+		 */
+		virtual void start() = 0;
+
+		/**
+		 * Stop playback
+		 */
+		virtual void stop()  = 0;
+
+
+		/*************
+		 ** Signals **
+		 *************/
+
+
+		/**
+		 * The 'progress' signal may be sent from the server to the client if a 
+		 * packet has been played.
+		 *
+		 * See: client.h, connection.h
+		 */
+		virtual void progress_sigh(Genode::Signal_context_capability sigh) = 0;
+
+		/**
+		 * The 'alloc' signal may be sent from the server to the client when the
+		 * stream queue leaves the 'full' state.
+		 *
+		 * See: client.h, connection.h
+		 */
+		virtual void alloc_sigh(Genode::Signal_context_capability sigh)    = 0;
+		
+		/**
+		 * The 'data_avail' signal is sent from the client to the surfer the
+		 * stream queue leaves the 'empty' state.
+		 */
+		virtual Genode::Signal_context_capability data_avail_sigh()        = 0;
+
+		GENODE_RPC(Rpc_start, void, start);
+		GENODE_RPC(Rpc_stop, void, stop);
+		GENODE_RPC(Rpc_dataspace, Genode::Dataspace_capability, dataspace);
+		GENODE_RPC(Rpc_progress_sigh, void, progress_sigh, Genode::Signal_context_capability);
+		GENODE_RPC(Rpc_alloc_sigh, void, alloc_sigh, Genode::Signal_context_capability);
+		GENODE_RPC(Rpc_data_avail_sigh, Genode::Signal_context_capability, data_avail_sigh);
+
+		GENODE_RPC_INTERFACE(Rpc_start, Rpc_stop, Rpc_dataspace, Rpc_progress_sigh,
+		                     Rpc_alloc_sigh, Rpc_data_avail_sigh);
+};
+
+#endif /* _INCLUDE__AUDIO_SESSION__AUDIO_SESSION_H_ */
diff --git a/os/include/audio_session/client.h b/os/include/audio_session/client.h
new file mode 100644
index 000000000..1e5280f1e
--- /dev/null
+++ b/os/include/audio_session/client.h
@@ -0,0 +1,147 @@
+/**
+ * \brief  Audio_out-session-client side
+ * \author Sebastian Sumpf
+ * \date   2012-12-20
+ */
+
+/*
+ * Copyright (C) 2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _INCLUDE__AUDIO_SESSEN__CLIENT_H_
+#define _INCLUDE__AUDIO_SESSEN__CLIENT_H_
+
+#include <base/env.h>
+#include <base/rpc_client.h>
+#include <audio_session/audio_session.h>
+
+namespace Audio_out {
+	struct Signal;
+	struct Session_client;
+}
+
+
+struct Audio_out::Signal
+{
+	Genode::Signal_receiver           recv;
+	Genode::Signal_context            context;
+	Genode::Signal_context_capability cap;
+
+	Signal() : cap(recv.manage(&context)) { }
+
+	void wait() { recv.wait_for_signal(); }
+};
+
+
+class Audio_out::Session_client : public Genode::Rpc_client<Session>
+{
+	private:
+
+		Signal _progress;
+		Signal _alloc;
+
+		Genode::Signal_transmitter _data_avail;
+
+	public:
+
+		/**
+		 * Constructor
+		 *
+		 * \param session          session capability
+		 * \param alloc_signal     true, install 'alloc_signal' receiver
+		 * \param progress_signal  true, install 'progress_signal' receiver
+		 */
+		Session_client(Genode::Capability<Session> session, bool alloc_signal, bool progress_signal)
+		:
+		  Genode::Rpc_client<Session>(session),
+		  _data_avail(call<Rpc_data_avail_sigh>())
+		{
+			/* ask server for stream data space and attach it */
+			_stream = static_cast<Stream *>(Genode::env()->rm_session()->attach(call<Rpc_dataspace>()));
+
+			if (progress_signal)
+				progress_sigh(_progress.cap);
+
+			if (alloc_signal)
+				alloc_sigh(_alloc.cap);
+
+		}
+
+
+		/*************
+		 ** Signals **
+		 *************/
+
+		void progress_sigh(Genode::Signal_context_capability sigh) { call<Rpc_progress_sigh>(sigh); }
+		void alloc_sigh(Genode::Signal_context_capability sigh) { call<Rpc_alloc_sigh>(sigh); }
+
+		Genode::Signal_context_capability data_avail_sigh() {
+			return Genode::Signal_context_capability(); }
+
+
+		/***********************
+		 ** Session interface **
+		 ***********************/
+
+		void start()
+		{
+			call<Rpc_start>();
+
+			/* reset tail pointer */
+			stream()->reset();
+		}
+
+		void stop() { call<Rpc_stop>();  }
+
+
+		/**********************************
+		 ** Session interface extensions **
+		 **********************************/
+
+		/**
+		 	* Wait for progress signal
+		 	*/
+		void wait_for_progress()
+		{
+			if (!_progress.cap.valid()) {
+				PWRN("Progress signal is not installed, will not block "
+				     "(enable in 'Audio_out::Connection')");
+				return;
+			}
+
+			_progress.wait();
+		}
+
+		/**
+		 * Wait for allocation signal. This can be used when the 'Stream' is full
+		 * and the applications want for block until the stream has free elements
+		 * again.
+		 */
+		void wait_for_alloc()
+		{ 
+			if (!_alloc.cap.valid()) {
+				PWRN("Alloc signal is not installed, will not block "
+				     "(enable in 'Audio_out::Connection')");
+				return;
+			}
+
+			_alloc.wait();
+		}
+
+		/**
+		 * Submit a packet
+		 */
+		void submit(Packet *packet)
+		{
+			bool empty = stream()->empty();
+
+			packet->_submit();
+			if (empty)
+				_data_avail.submit();
+		}
+};
+
+#endif /* _INCLUDE__AUDIO_SESSEN__CLIENT_H_ */
diff --git a/os/include/audio_session/connection.h b/os/include/audio_session/connection.h
new file mode 100644
index 000000000..cde360eaf
--- /dev/null
+++ b/os/include/audio_session/connection.h
@@ -0,0 +1,51 @@
+/*
+ * \brief  Connection to audio service
+ * \author Sebastian Sumpf
+ * \date   2012-12-20
+ */
+
+/*
+ * Copyright (C) 2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _INCLUDE__AUDIO_SESSION__CONNECTION_H_
+#define _INCLUDE__AUDIO_SESSION__CONNECTION_H_
+
+#include <audio_session/client.h>
+#include <base/connection.h>
+#include <base/allocator.h>
+
+
+namespace Audio_out {
+	struct Connection;
+}
+
+
+struct Audio_out::Connection : Genode::Connection<Session>, Audio_out::Session_client
+{
+	/**
+	 * Constructor
+	 *
+	 * \param channel          channel identifier (e.g., "front left")
+	 * \param alloc_signal     install 'alloc_signal', the client may thean use
+	 *                         'wait_for_alloc' when the stream is full
+	 * \param progress_signal  install progress signal, the client may then call
+	 *                         'wait_for_progress' which is send when the server
+	 *                         processed one or more packets
+	 */
+	Connection(const char              *channel,
+	           bool                     alloc_signal = true,
+	           bool                     progress_signal = false)
+	:
+		Genode::Connection<Session>(
+			session("ram_quota=%zd, channel=\"%s\"",
+			        2*4096 + sizeof(Stream), channel)),
+		Session_client(cap(), alloc_signal, progress_signal)
+	{ }
+};
+
+
+#endif /* _INCLUDE__AUDIO_SESSION__CONNECTION_H_ */
diff --git a/os/include/audio_session/rpc_object.h b/os/include/audio_session/rpc_object.h
new file mode 100644
index 000000000..722a57402
--- /dev/null
+++ b/os/include/audio_session/rpc_object.h
@@ -0,0 +1,124 @@
+/*
+ * \brief  Server side audio-session interface
+ * \author Sebastian Sumpf
+ * \date   2012-12-10
+ */
+
+/*
+ * Copyright (C) 2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _INCLUDE__AUDIO_SESSION__RPC_OBJECT_H_
+#define _INCLUDE__AUDIO_SESSION__RPC_OBJECT_H_
+
+#include <base/env.h>
+#include <base/rpc_server.h>
+#include <audio_session/audio_session.h>
+
+
+namespace Audio_out {
+	class Session_rpc_object;
+}
+
+
+class Audio_out::Session_rpc_object : public Genode::Rpc_object<Audio_out::Session,
+                                                            Session_rpc_object>
+{
+	protected:
+
+		bool                             _stopped;   /* state */
+		Genode::Ram_dataspace_capability _ds;        /* contains Audio_out_stream */
+		Genode::Signal_transmitter       _progress;
+		Genode::Signal_transmitter       _alloc;
+
+		Genode::Signal_context_capability _data_cap;
+
+		bool _progress_sigh; /* progress signal on/off */
+		bool _alloc_sigh;    /* alloc signal on/off */
+
+	public:
+
+		Session_rpc_object(Genode::Signal_context_capability data_cap)
+		:
+		  _stopped(true), _data_cap(data_cap),
+		  _progress_sigh(false), _alloc_sigh(false)
+		{
+			_ds = Genode::env()->ram_session()->alloc(sizeof(Stream));
+			_stream = static_cast<Stream *>(Genode::env()->rm_session()->attach(_ds));
+		}
+
+		virtual ~Session_rpc_object()
+		{
+			if (_ds.valid()) {
+				Genode::env()->rm_session()->detach(_stream);
+				Genode::env()->ram_session()->free(_ds);
+			}
+		}
+
+		/**************
+		 ** Signals  **
+		 **************/
+
+		void progress_sigh(Genode::Signal_context_capability sigh)
+		{
+			_progress.context(sigh);
+			_progress_sigh = true;
+		}
+
+		Genode::Signal_context_capability data_avail_sigh() {
+			return _data_cap; }
+
+		void alloc_sigh(Genode::Signal_context_capability sigh)
+		{
+			_alloc.context(sigh);
+			_alloc_sigh = true;
+		}
+
+
+		/***********************
+		 ** Session interface **
+		 ***********************/
+
+		void start() { _stopped = false; }
+		void stop()  { _stopped = true; }
+
+		Genode::Dataspace_capability dataspace() { return _ds; }
+
+
+		/**********************************
+		 ** Session interface extensions **
+		 **********************************/
+
+		 /**
+		 	* Send 'progress' signal
+		 	*/
+		void progress_submit()
+		{
+			if (_progress_sigh)
+				_progress.submit();
+		}
+
+		/**
+		 * Send 'alloc' signal
+		 */
+		void alloc_submit()
+		{
+			if (_alloc_sigh)
+				_alloc.submit();
+		}
+
+		/**
+		 * Return true if client state is stopped
+		 */
+		bool stopped() const { return _stopped; }
+
+		/**
+		 * Return true if client session is active
+		 */
+		bool active()  const { return !_stopped; }
+};
+
+#endif /* _INCLUDE__AUDIO_SESSION__RPC_OBJECT_H_ */