diff --git a/services/audioflinger/BufferProviders.h b/services/audioflinger/BufferProviders.h
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+++ b/services/audioflinger/BufferProviders.h
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+/*
+ * Copyright (C) 2015 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_BUFFER_PROVIDERS_H
+#define ANDROID_BUFFER_PROVIDERS_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <hardware/audio_effect.h>
+#include <media/AudioBufferProvider.h>
+#include <system/audio.h>
+
+namespace android {
+
+// ----------------------------------------------------------------------------
+
+class PassthruBufferProvider : public AudioBufferProvider {
+public:
+    PassthruBufferProvider() : mTrackBufferProvider(NULL) { }
+
+    virtual ~PassthruBufferProvider() { }
+
+    // call this to release the buffer to the upstream provider.
+    // treat it as an audio discontinuity for future samples.
+    virtual void reset() { }
+
+    // set the upstream buffer provider. Consider calling "reset" before this function.
+    virtual void setBufferProvider(AudioBufferProvider *p) {
+        mTrackBufferProvider = p;
+    }
+
+protected:
+    AudioBufferProvider *mTrackBufferProvider;
+};
+
+// Base AudioBufferProvider class used for DownMixerBufferProvider, RemixBufferProvider,
+// and ReformatBufferProvider.
+// It handles a private buffer for use in converting format or channel masks from the
+// input data to a form acceptable by the mixer.
+// TODO: Make a ResamplerBufferProvider when integers are entirely removed from the
+// processing pipeline.
+class CopyBufferProvider : public PassthruBufferProvider {
+public:
+    // Use a private buffer of bufferFrameCount frames (each frame is outputFrameSize bytes).
+    // If bufferFrameCount is 0, no private buffer is created and in-place modification of
+    // the upstream buffer provider's buffers is performed by copyFrames().
+    CopyBufferProvider(size_t inputFrameSize, size_t outputFrameSize,
+            size_t bufferFrameCount);
+    virtual ~CopyBufferProvider();
+
+    // Overrides AudioBufferProvider methods
+    virtual status_t getNextBuffer(Buffer *buffer, int64_t pts);
+    virtual void releaseBuffer(Buffer *buffer);
+
+    // Overrides PassthruBufferProvider
+    virtual void reset();
+
+    // this function should be supplied by the derived class.  It converts
+    // #frames in the *src pointer to the *dst pointer.  It is public because
+    // some providers will allow this to work on arbitrary buffers outside
+    // of the internal buffers.
+    virtual void copyFrames(void *dst, const void *src, size_t frames) = 0;
+
+protected:
+    const size_t         mInputFrameSize;
+    const size_t         mOutputFrameSize;
+private:
+    AudioBufferProvider::Buffer mBuffer;
+    const size_t         mLocalBufferFrameCount;
+    void                *mLocalBufferData;
+    size_t               mConsumed;
+};
+
+// DownmixerBufferProvider derives from CopyBufferProvider to provide
+// position dependent downmixing by an Audio Effect.
+class DownmixerBufferProvider : public CopyBufferProvider {
+public:
+    DownmixerBufferProvider(audio_channel_mask_t inputChannelMask,
+            audio_channel_mask_t outputChannelMask, audio_format_t format,
+            uint32_t sampleRate, int32_t sessionId, size_t bufferFrameCount);
+    virtual ~DownmixerBufferProvider();
+    //Overrides
+    virtual void copyFrames(void *dst, const void *src, size_t frames);
+
+    bool isValid() const { return mDownmixHandle != NULL; }
+    static status_t init();
+    static bool isMultichannelCapable() { return sIsMultichannelCapable; }
+
+protected:
+    effect_handle_t    mDownmixHandle;
+    effect_config_t    mDownmixConfig;
+
+    // effect descriptor for the downmixer used by the mixer
+    static effect_descriptor_t sDwnmFxDesc;
+    // indicates whether a downmix effect has been found and is usable by this mixer
+    static bool                sIsMultichannelCapable;
+    // FIXME: should we allow effects outside of the framework?
+    // We need to here. A special ioId that must be <= -2 so it does not map to a session.
+    static const int32_t SESSION_ID_INVALID_AND_IGNORED = -2;
+};
+
+// RemixBufferProvider derives from CopyBufferProvider to perform an
+// upmix or downmix to the proper channel count and mask.
+class RemixBufferProvider : public CopyBufferProvider {
+public:
+    RemixBufferProvider(audio_channel_mask_t inputChannelMask,
+            audio_channel_mask_t outputChannelMask, audio_format_t format,
+            size_t bufferFrameCount);
+    //Overrides
+    virtual void copyFrames(void *dst, const void *src, size_t frames);
+
+protected:
+    const audio_format_t mFormat;
+    const size_t         mSampleSize;
+    const size_t         mInputChannels;
+    const size_t         mOutputChannels;
+    int8_t               mIdxAry[sizeof(uint32_t) * 8]; // 32 bits => channel indices
+};
+
+// ReformatBufferProvider derives from CopyBufferProvider to convert the input data
+// to an acceptable mixer input format type.
+class ReformatBufferProvider : public CopyBufferProvider {
+public:
+    ReformatBufferProvider(int32_t channelCount,
+            audio_format_t inputFormat, audio_format_t outputFormat,
+            size_t bufferFrameCount);
+    virtual void copyFrames(void *dst, const void *src, size_t frames);
+
+protected:
+    const uint32_t       mChannelCount;
+    const audio_format_t mInputFormat;
+    const audio_format_t mOutputFormat;
+};
+
+// ----------------------------------------------------------------------------
+} // namespace android
+
+#endif // ANDROID_BUFFER_PROVIDERS_H