webrtc/common_audio/resampler/include/resampler.h

/*
 *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */


/*
 * A wrapper for resampling a numerous amount of sampling combinations.
 */

#ifndef WEBRTC_RESAMPLER_RESAMPLER_H_
#define WEBRTC_RESAMPLER_RESAMPLER_H_

#include "webrtc/typedefs.h"

namespace webrtc
{

// TODO(andrew): the implementation depends on the exact values of this enum.
// It should be rewritten in a less fragile way.
enum ResamplerType
{
    // 4 MSB = Number of channels
    // 4 LSB = Synchronous or asynchronous

    kResamplerSynchronous = 0x10,
    kResamplerAsynchronous = 0x11,
    kResamplerSynchronousStereo = 0x20,
    kResamplerAsynchronousStereo = 0x21,
    kResamplerInvalid = 0xff
};

// TODO(andrew): doesn't need to be part of the interface.
enum ResamplerMode
{
    kResamplerMode1To1,
    kResamplerMode1To2,
    kResamplerMode1To3,
    kResamplerMode1To4,
    kResamplerMode1To6,
    kResamplerMode1To12,
    kResamplerMode2To3,
    kResamplerMode2To11,
    kResamplerMode4To11,
    kResamplerMode8To11,
    kResamplerMode11To16,
    kResamplerMode11To32,
    kResamplerMode2To1,
    kResamplerMode3To1,
    kResamplerMode4To1,
    kResamplerMode6To1,
    kResamplerMode12To1,
    kResamplerMode3To2,
    kResamplerMode11To2,
    kResamplerMode11To4,
    kResamplerMode11To8
};

class Resampler
{

public:
    Resampler();
    // TODO(andrew): use an init function instead.
    Resampler(int inFreq, int outFreq, ResamplerType type);
    ~Resampler();

    // Reset all states
    int Reset(int inFreq, int outFreq, ResamplerType type);

    // Reset all states if any parameter has changed
    int ResetIfNeeded(int inFreq, int outFreq, ResamplerType type);

    // Synchronous resampling, all output samples are written to samplesOut
    int Push(const int16_t* samplesIn, int lengthIn, int16_t* samplesOut,
             int maxLen, int &outLen);

    // Asynchronous resampling, input
    int Insert(int16_t* samplesIn, int lengthIn);

    // Asynchronous resampling output, remaining samples are buffered
    int Pull(int16_t* samplesOut, int desiredLen, int &outLen);

private:
    // Generic pointers since we don't know what states we'll need
    void* state1_;
    void* state2_;
    void* state3_;

    // Storage if needed
    int16_t* in_buffer_;
    int16_t* out_buffer_;
    int in_buffer_size_;
    int out_buffer_size_;
    int in_buffer_size_max_;
    int out_buffer_size_max_;

    // State
    int my_in_frequency_khz_;
    int my_out_frequency_khz_;
    ResamplerMode my_mode_;
    ResamplerType my_type_;

    // Extra instance for stereo
    Resampler* slave_left_;
    Resampler* slave_right_;
};

}  // namespace webrtc

#endif // WEBRTC_RESAMPLER_RESAMPLER_H_