diff --git a/media/libeffects/AudioEqualizer.h b/media/libeffects/AudioEqualizer.h
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+/*
+ * Copyright 2009, 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 AUDIOEQUALIZER_H_
+#define AUDIOEQUALIZER_H_
+
+#include "AudioCommon.h"
+
+namespace android {
+
+class AudioShelvingFilter;
+class AudioPeakingFilter;
+
+// A parametric audio equalizer. Supports an arbitrary number of bands and
+// presets.
+// The EQ is composed of a low-shelf, zero or more peaking filters and a high
+// shelf, where each band has frequency and gain controls, and the peaking
+// filters have an additional bandwidth control.
+class AudioEqualizer {
+public:
+    // Configuration of a single band.
+    struct BandConfig {
+        // Gain in millibel.
+        int32_t gain;
+        // Frequency in millihertz.
+        uint32_t freq;
+        // Bandwidth in cents (ignored on shelving filters).
+        uint32_t bandwidth;
+    };
+
+    // Preset configuration.
+    struct PresetConfig {
+        // Human-readable name.
+        const char * name;
+        // An array of size nBands where each element is a configuration for the
+        // corresponding band.
+        const BandConfig * bandConfigs;
+    };
+
+    // This value is used when requesting current preset, and EQ is not using a
+    // preset.
+    static const int PRESET_CUSTOM = -1;
+
+    // Get the required memory size for an instance of this class.
+    // nBands   Number of bands required in the instance.
+    static size_t GetInstanceSize(int nBands);
+
+    // Create an instance of this class.
+    // If succeeds, a respective call is expected to freeInstance(), regardless
+    // of who owns the context memory.
+    // pMem         A memory buffer of at least the size returned by
+    //              GetInstanceSize(), where the instance context is to be
+    //              stored. If NULL, it will be automatically allocated (using
+    //              malloc).
+    // nBands       Number of bands. Must be >= 2.
+    // nChannels    Number of input/output channels (interlaced).
+    // sampleRate   The input/output sample rate, in Hz.
+    // presets      The presets configuration. May be NULL, but in that case the
+    //              client is required not to call preset-related functions.
+    //              This array is owned by the client and is not copied. It
+    //              must be kept valid by the client as long as the instance is
+    //              alive.
+    // nPresets     Number of elements in the presets array.
+    // returns      The instance if success. NULL if pMem is NULL and allocation
+    //              failed.
+    static AudioEqualizer * CreateInstance(void * pMem, int nBands,
+                                           int nChannels,
+                                           int sampleRate,
+                                           const PresetConfig * presets,
+                                           int nPresets);
+
+    // Reconfiguration of the filter. Changes input/output format, but does not
+    // alter current parameter values. Causes reset of the delay lines.
+    // nChannels  Number of input/output channels (interlaced).
+    // sampleRate The input/output sample rate, in Hz.
+    void configure(int nChannels, int sampleRate);
+
+    // Resets the filter parameters to the following values:
+    // frequency: 0
+    // gain: 0
+    // bandwidth: 1200 cents.
+    // It also disables the filter. Does not clear the delay lines.
+    void reset();
+
+    // Clears delay lines. Does not alter parameter values.
+    void clear();
+
+    // Frees the object. Will free the memory if the object owned it, i.e. if
+    // a NULL pointer was passed to CreateInstance as pMem.
+    void free();
+
+    // Sets gain value. Actual change will only take place upon commit().
+    // This value will be remembered even if the filter is in disabled() state.
+    // band     The band to set the gain for.
+    // millibel Gain value in millibel (1/100 of decibel).
+    void setGain(int band, int32_t millibel);
+
+    // Gets gain of a certain band. This is always the last value set (or
+    // default value after reset).
+    // band     The band to get the gain for.
+    // returns  Gain value in millibel (1/100 of decibel).
+    int32_t getGain(int band) const;
+
+    // Sets cutoff frequency value. Actual change will only take place upon
+    // commit().
+    // This value will be remembered even if the filter is in disabled() state.
+    // band       The band to set the frequency for.
+    // millihertz Frequency value in mHz.
+    void setFrequency(int band, uint32_t millihertz);
+
+    // Gets frequency of a certain band. This is always the last value set (or
+    // default value after reset).
+    // band     The band to get the frequency for.
+    // returns  Frequency value in mHz.
+    uint32_t getFrequency(int band) const;
+
+    // Sets bandwidth value. Actual change will only take place upon commit().
+    // This value will be remembered even if the filter is in disabled() state.
+    // If called on the first or last band, this call is ignored.
+    // band  The band to set the frequency for.
+    // cents Bandwidth value in cents (1/1200 octave).
+    void setBandwidth(int band, uint32_t cents);
+
+    // Gets bandwidth of a certain band. This is always the last value set (or
+    // default value after reset). For the first and last bands, 0 is always
+    // returned.
+    // band     The band to get the bandwidth for.
+    // returns  Bandwidth value in cents (1/1200 octave).
+    uint32_t getBandwidth(int band) const;
+
+    // Gets lower and upper boundaries of a band.
+    // For the low shelf, the low bound is 0 and the high bound is the band
+    // frequency.
+    // For the high shelf, the low bound is the band frequency and the high
+    // bound is Nyquist.
+    // For the peaking filters, they are the gain[dB]/2 points.
+    void getBandRange(int band, uint32_t & low, uint32_t & high) const;
+
+    // Gets a human-readable name for a preset ID. Will return "Custom" if
+    // PRESET_CUSTOM is passed.
+    // preset       The preset ID. Must be less than number of presets.
+    const char * getPresetName(int preset) const;
+
+    // Gets the number of presets.
+    int getNumPresets() const;
+
+    // Gets the currently set preset ID.
+    // Will return PRESET_CUSTOM in case the EQ parameters have been modified
+    // manually since a preset was set.
+    int getPreset() const;
+
+    // Sets the current preset by ID.
+    // All the band parameters will be overridden.
+    // Change will not be applied until commit() is called.
+    // preset       The preset ID. Must be less than number of presets.
+    //              PRESET_CUSTOM is NOT a valid value here.
+    void setPreset(int preset);
+
+    // Applies all parameter changes done to this point in time.
+    // If the filter is disabled, the new parameters will take place when it is
+    // enabled again. Does not introduce artifacts, unless immediate is set.
+    // immediate    Whether to apply change abruptly (ignored if filter is
+    // disabled).
+   void commit(bool immediate = false);
+
+    // Process a buffer of input data. The input and output should contain
+    // frameCount * nChannels interlaced samples. Processing can be done
+    // in-place, by passing the same buffer as both arguments.
+    // pIn          Input buffer.
+    // pOut         Output buffer.
+    // frameCount   Number of frames to produce on each call to process().
+    void process(const audio_sample_t * pIn, audio_sample_t * pOut,
+                 int frameCount);
+
+    // Enables the filter, so it would start processing input. Does not
+    // introduce artifacts, unless immediate is set.
+    // immediate    Whether to apply change abruptly.
+    void enable(bool immediate = false);
+
+    // Disabled (bypasses) the filter. Does not introduce artifacts, unless
+    // immediate is set.
+    // immediate    Whether to apply change abruptly.
+    void disable(bool immediate = false);
+
+    // Returns the band with the maximum influence on a given frequency.
+    // Result is unaffected by whether EQ is enabled or not, or by whether
+    // changes have been committed or not.
+    // targetFreq   The target frequency, in millihertz.
+    int getMostRelevantBand(uint32_t targetFreq) const;
+
+private:
+    // Bottom frequency, in mHz.
+    static const int kMinFreq = 20000;
+    // Sample rate, in Hz.
+    int mSampleRate;
+    // Number of peaking filters. Total number of bands is +2.
+    int mNumPeaking;
+    // Preset configurations.
+    const PresetConfig * mpPresets;
+    // Number of elements in mpPresets;
+    int mNumPresets;
+    // Current preset.
+    int mCurPreset;
+
+    // Memory space to free when instance is deleted, or NULL if no memory is
+    // owned.
+    void * mpMem;
+    // The low-shelving filter.
+    AudioShelvingFilter * mpLowShelf;
+    // The high-shelving filter.
+    AudioShelvingFilter * mpHighShelf;
+    // An array of size mNumPeaking of peaking filters.
+    AudioPeakingFilter * mpPeakingFilters;
+
+    // Constructor. Resets the filter (see reset()). Must call init() doing
+    // anything else.
+    // pMem       Memory buffer for bands.
+    // nChannels  Number of input/output channels (interlaced).
+    // sampleRate The input/output sample rate, in Hz.
+    // ownMem     Whether pMem is owned by me.
+    // presets      The presets configuration. May be NULL, but in that case the
+    //              client is required not to call preset-related functions.
+    //              This array is owned by the client and is not copied. It
+    //              must be kept valid by the client as long as the instance is
+    //              alive.
+    // nPresets     Number of elements in the presets array.
+    AudioEqualizer(void * pMem, int nBands, int nChannels, int sampleRate,
+                   bool ownMem, const PresetConfig * presets, int nPresets);
+};
+
+}
+
+#endif // AUDIOEQUALIZER_H_