diff --git a/include/hardware/AudioHardwareInterface.h b/include/hardware/AudioHardwareInterface.h
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+++ b/include/hardware/AudioHardwareInterface.h
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+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_AUDIO_HARDWARE_INTERFACE_H
+#define ANDROID_AUDIO_HARDWARE_INTERFACE_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <utils/Errors.h>
+#include <utils/Vector.h>
+#include <utils/String16.h>
+
+#include <media/IAudioFlinger.h>
+#include "media/AudioSystem.h"
+
+
+namespace android {
+
+// ----------------------------------------------------------------------------
+
+/**
+ * This is the abstraction interface for the audio output hardware. It provides 
+ * information about various properties of the audio output hardware driver.
+ */
+class AudioStreamOut {
+public:
+    virtual             ~AudioStreamOut() = 0;
+    
+    /** return audio sampling rate in hz - eg. 44100 */
+    virtual uint32_t    sampleRate() const = 0;
+    
+    /** returns size of output buffer - eg. 4800 */
+    virtual size_t      bufferSize() const = 0;
+    
+    /** 
+     * return number of output audio channels. 
+     * Acceptable values are 1 (mono) or 2 (stereo) 
+     */
+    virtual int         channelCount() const = 0;
+    
+    /**
+     * return audio format in 8bit or 16bit PCM format - 
+     * eg. AudioSystem:PCM_16_BIT 
+     */
+    virtual int         format() const = 0;
+    
+    /** 
+     * This method can be used in situations where audio mixing is done in the
+     * hardware. It is a direct interface to the hardware to set the volume as
+     * as opposed to controlling this via the framework. It could be multiple 
+     * PCM outputs or hardware accelerated codecs such as MP3 or AAC
+     */
+    virtual status_t    setVolume(float volume) = 0;
+    
+    /** write audio buffer to driver. Returns number of bytes written */
+    virtual ssize_t     write(const void* buffer, size_t bytes) = 0;
+
+    /** dump the state of the audio output device */
+    virtual status_t dump(int fd, const Vector<String16>& args) = 0; 
+};
+
+/**
+ * This is the abstraction interface for the audio input hardware. It defines 
+ * the various properties of the audio hardware input driver.  
+ */
+class AudioStreamIn {
+public:
+    virtual             ~AudioStreamIn() = 0;
+    
+    /** return the input buffer size allowed by audio driver */
+    virtual size_t      bufferSize() const = 0;
+
+    /** return the number of audio input channels */
+    virtual int         channelCount() const = 0;
+    
+    /** 
+     * return audio format in 8bit or 16bit PCM format - 
+     * eg. AudioSystem:PCM_16_BIT 
+     */
+    virtual int         format() const = 0;
+
+    /** set the input gain for the audio driver. This method is for
+     *  for future use */
+    virtual status_t    setGain(float gain) = 0;
+    
+    /** read audio buffer in from audio driver */
+    virtual ssize_t     read(void* buffer, ssize_t bytes) = 0;
+
+    /** dump the state of the audio input device */
+    virtual status_t dump(int fd, const Vector<String16>& args) = 0;
+};
+
+/** 
+ * This defines the interface to the audio hardware abstraction layer. It 
+ * supports setting and getting parameters, selecting audio routing paths and 
+ * defining input and output streams.
+ * 
+ * AudioFlinger initializes the audio hardware and immediately opens an output 
+ * stream. Audio routing can be set to output to handset, speaker, bluetooth or 
+ * headset. 
+ *
+ * The audio input stream is initialized when AudioFlinger is called to carry 
+ * out a record operation. 
+ */
+class AudioHardwareInterface
+{
+public:
+                        AudioHardwareInterface();
+    virtual             ~AudioHardwareInterface() { }
+
+    /** 
+     * check to see if the audio hardware interface has been initialized. 
+     * return status based on values defined in include/utils/Errors.h 
+     */
+    virtual status_t    initCheck() = 0;
+
+    /** 
+     * put the audio hardware into standby mode to conserve power. Returns 
+     * status based on include/utils/Errors.h 
+     */
+    virtual status_t    standby() = 0;
+
+    /** set the audio volume of a voice call. Range is between 0.0 and 1.0 */
+    virtual status_t    setVoiceVolume(float volume) = 0;
+    
+    /** 
+     * set the audio volume for all audio activities other than voice call. 
+     * Range between 0.0 and 1.0. IF any value other than NO_ERROR is returned,
+     * the software mixer will emulate this capability.
+     */
+    virtual status_t    setMasterVolume(float volume) = 0;
+
+    /**  
+     * Audio routing methods. Routes defined in include/hardware/AudioSystem.h. 
+     * Audio routes can be (ROUTE_EARPIECE | ROUTE_SPEAKER | ROUTE_BLUETOOTH 
+     *                    | ROUTE_HEADSET)
+     * 
+     * setRouting sets the routes for a mode. This is called at startup. It is
+     * also called when a new device is connected, such as a wired headset is 
+     * plugged in or a Bluetooth headset is paired
+     */
+    virtual status_t    setRouting(int mode, uint32_t routes);
+    
+    virtual status_t    getRouting(int mode, uint32_t* routes);
+    
+    /**
+     * setMode is called when the audio mode changes. NORMAL mode is for
+     * standard audio playback, RINGTONE when a ringtone is playing and IN_CALL
+     * when a call is in progress.
+     */
+    virtual status_t    setMode(int mode);
+    virtual status_t    getMode(int* mode);
+
+    // mic mute
+    virtual status_t    setMicMute(bool state) = 0;
+    virtual status_t    getMicMute(bool* state) = 0;
+
+    // Temporary interface, do not use
+    // TODO: Replace with a more generic key:value get/set mechanism
+    virtual status_t    setParameter(const char* key, const char* value);
+
+    /** This method creates and opens the audio hardware output stream */
+    virtual AudioStreamOut* openOutputStream(
+                                int format=0,
+                                int channelCount=0,
+                                uint32_t sampleRate=0) = 0;
+
+    /** This method creates and opens the audio hardware input stream */
+    virtual AudioStreamIn* openInputStream(
+                                int format,
+                                int channelCount,
+                                uint32_t sampleRate) = 0;
+    
+    /**This method dumps the state of the audio hardware */
+    virtual status_t dumpState(int fd, const Vector<String16>& args);
+
+    static AudioHardwareInterface* create();
+
+protected:
+    /**
+     * doRouting actually initiates the routing to occur. A call to setRouting 
+     * or setMode may result in a routing change. The generic logic will call 
+     * doRouting when required. If the device has any special requirements these
+     * methods can be overriden.
+     */
+    virtual status_t    doRouting() = 0;
+    
+    virtual status_t dump(int fd, const Vector<String16>& args) = 0;
+
+    int             mMode;
+    uint32_t        mRoutes[AudioSystem::NUM_MODES];
+};
+
+// ----------------------------------------------------------------------------
+
+extern "C" AudioHardwareInterface* createAudioHardware(void);
+
+}; // namespace android
+
+#endif // ANDROID_AUDIO_HARDWARE_INTERFACE_H